chapters 1 to 9

i

TABLE OF CONTENTS

Chapter 1: INTRODUCTION 1

1.1. Importance of electric usage in new human's life

1.2. History of electric industry and its expansion

1.3. Distribution system planning

1.4. Factors affecting planning system

1.5. Objective of the projects

1.6. Summary

Chapter 2: BUILDING WIRING CALUCLATION 4

2.1. Introduction

2.2. General Overview on Light 2.2.1. Nature of light

2.2.2. Basic Definitions

2.2.3. Requirements of a good lighting scheme

2.2.4. Factors affecting the illumination and wattage of a certain lamp

2.3. Types of lighting schemes

2.3.1. Direct Lighting

2.3.2. Semi-direct Lighting

2.3.3. Indirect lighting

2.3.4. Semi-indirect lighting

2.3.5. General lighting

2.4. Artificial sources of light 2.4.1. Arc lamps

2.4.2. Incandescent electric lamps

2.4.3. Discharge lamps

2.5. Building wiring calculations 2.5.1. Lighting loads calculations

2.5.2. Socket Loads

2.5.3. Riser calculations

2.6. General points to be considered in the design

2.7. Calculation of loads for flats & villas 2.7.1. Flat type (A)

2.7.2. Flat type (B)

2.7.3. Flat type (C)

2.7.4. Flat type (D)

2.7.5. Flat type (E)

2.7.6. Villa type (a)

2.7.7. Villa type (b)

2.7.8. Villa type (C)

ii

Chapter 3: LOW VOLATGE DISTUBUTION NETWORK PLANNING 84

3.1. Introduction

3.2. General Overview on the distribution system 3.2.1. Distribution Transformer

3.2.2. Distribution Box (Pillar)

3.2.3. Building Box (Coffree)

3.3. Low Voltage Network (LVN) types 3.3.1. Radial LVN

3.3.2. Open Loop (Ring) LVN

3.4. General points to be considered in design

3.5. Planning of Distribution Network in the Residential Area 3.5.1. Calculation of Distribution Boxes (Pillars) and Feeders ratings

3.5.2. Calculation of Transformer and feeders ratings

3.5.3. Voltage drop Calculations

3.5.4. Short Circuit Current Calculations

3.6. Example of calculations

Chapter 4: MEDIUM VOLTAGE DISTRIBUTION NETWORK 103

4.1. Introduction

4.2. General Overview on Medium Voltage Network (Primary Distribution Network)

4.3. Medium Voltage Network Types 4.3.1. Medium voltage switchboard supply modes

4.3.2. Medium voltage network structure

4.4. Calculation of the distribution point and sizing of the 22 KV cables

Chapter 5: 66/22 KV SUBSTATION 120

5.1. Introduction

5.2. General Overview

5.3. Substation Classifications

5.4. Types of substation

5.5. Substation layout

5.6. Substation Equipment

5.7. Earthing and Bonding

5.8. Essential Civil Structure in outdoor substations

5.9. Description of the Single Line Diagram and Layout for the Present 66/22KV

Substation

iii

Chapter 6: POWER SYSTEM PROTECTION 134

6.1. Introduction

6.2. General Overview

6.3. Types of faults in power systems

6.4. Division of power systems into protective zones

6.5. Fuses

6.6. Basic elements of protective switchgear

6.7. Relay

6.8. Differential Protection of Power systems

6.9. Applications:

6.10. Circuit Breakers

Chapter 7: STREET LIGHTING 158

7.1. Introduction

7.2. Classification of factors affecting the design of street lighting

7.3. Street lighting arrangements

7.4. Street lighting design process

7.5. Types of lamps used in Street lighting

7.6. Methods of switching of lamps

7.7. Street lighting system

7.8. Lighting control and Wiring system

7.9. Design of the street lighting scheme using DIALux program

Chapter 8: SYSTEM GROUNDING 171

8.1. The importance of Earthing

8.2. Types of earthing

8.3. Safety or protective

8.2. Types of earthing

8.4. System Earthing

8.5. Methods of Earting

8.6. Circuits & equations

8.7. Earth Resistivity & Gradient

8.8. Earth electrodes &networks

8.9. measurement of earth electrode resistance & earth loop impedance

8.11. The high pulse voltage E.S.E. lightening conductor

8.10. Substation earthing

iv

Chapter 9: The Shopping Mall 181 9.1. Introduction

9.2. Ground Floor 9.2.1. Ground Floor Lighting Calculations

9.2.2. Ground Floor Socket Calculations & Wiring

9.2.3. Ground Floor Local Feeders

9.2.4. Ground Floor SMDBs & Cable Tray Dimension

9.2.5. Ground Floor Emergency Backup Scheme

9.3 First Floor 9.3.1. First Floor Lighting Calculations

9.3.2. First Floor Socket Calculations & Wiring

9.3.3. First Floor Local Feeders

9.3.4. First Floor SMDBs & Cable Tray Dimension

9.3.5. First Floor Emergency Backup Scheme

9.4. Second Floor 9.4.1. Second Floor Lighting Calculations

9.4.2. Second Floor Socket Calculations & Wiring

9.4.3. Second Floor Local Feeders

9.4.4. Second Floor SMDBs & Cable Tray Dimension

9.4.5. Second Floor Emergency Backup Scheme

9.5. Air Conditioner and Elevator Panel (Roof Panel)

9.6. Mall Panel Boards Connection Diagram & Cable Specifications 9.7.2. Electrical Rooms 2 Panel Boards

9.7. Detailed Single Line Diagram of Each Panel Board 9.7.1. Electrical Rooms 1 Panel Boards

9.7.2. Electrical Rooms 2 Panel Boards

9.7.3. Emergency Panel Boards

9.8. Emergency Operation 9.8.1. ATS specifications

9.8.2. Emergency Generator

Chapter 10 223

Appendices

References

Introduction

Chapter 1

CHAPTER 1 INTRODUCTION

1

Chapter 1

INTRODUCTION

1.1 Importance of electric usage in new human's life:

As long as the electricity is available, no one thinks much about it. The importance

is realized when the power goes out. Whether it’s during the day or at night,

electricity keeps our lives in order. It affects your business, your schedule and even

your entertainment.

Electricity runs everything in our everyday life. Gas stations can’t pump gas

without it. Businesses have to close because their cash registers won’t work without

it. Restaurants can’t cook food without it. Our lives almost come to a standstill

without electricity.

These are the times when back up electricity is most needed and becomes very

important. It can keep our clocks running, so we aren’t late for work. Appointments

will be kept on time. It’s important to keep on schedule and backup electricity can do

just that.

1.2 History of electric industry and its expansion

The electric utility industry was born in 1882 when the 1st electric power station in

New York City went into operation .The industry grew up rapidly & generation

stations & transmission & distribution networks have spread across the entire

country., Energy is expected to be increasingly converted to electricity after year

2000. In the past the distribution systems represented over 80 percent of total system

investment .Production expenses is the major factor in the total electrical operation &

maintenance.

1.3 Distribution system planning

System planning is essential to assure that the growing demand for electricity can

be satisfied by both technically adequate & reasonably economical.

It is application has unfortunately been somewhat neglected. In the future, electric

utilities will need a fast & economical planning to provide the necessary economical,

reliable, and safe electric energy to consumers can be satisfied in an optimum way by

additional distribution systems, from the secondary conductors through the bulk

power substations. The distribution system's particularly important to an electrical utility for two

reasons:

It's close proximity to the ultimate customer. 1-

2-It's high investment cost.

http://www.energyigloo.com/

http://www.energyigloo.com/


2

1.4 Factors affecting planning system The number & complexity affecting system planning appears initially to be

staggering. The planning problem is an attempt to minimize the cost of sub-

transmission, sub-stations, feeders, as well as losses cost.

A) Load forecasting. The load growth of the geographical area served by a utility company is the

most important factor as it's essential to the planning process.

There are 2 common time scales:

*Long range (with time horizons on the order of 15~20 years old).

*Short range (with time horizons on the order of 5 years old).

B) Substation expansion. The planner makes a decision based on tangible or in tangible information. For ex.,

the forecasted load, load density, & load growth may require a substation or a new

substation construction .Here capacity & forecasted loads can play major roles.

C) Substation site selection. The distance from the load centers & from the existing sub-transmission lines as

well as other limitations such as availability of land, its cost, & land use regulations

are important.

The s/s sitting process can be described as a screening procedure through which all

possible locations for a site are passed .The service region is the area under

evaluation.

D) Other factors.

1.5 Objective of the projects Our target in this project is to study the factors affecting the Planning and

Distribution of a Power System in some specified areas; Agriculture, Residential, City

Center, Industrial.

At first, we’ll begin by forecasting of loads in these areas for the next 10 years

(approximately) depending on a well known data of the previous years, so we are able

to calculate the load densities in these areas as follows:

Around 4~5 persons for each flat according to the living life level.

This table shows the different areas and the number of its people:

Zone Zone Area(m²) Unit Area(m2) Class Population(persons)

Green 58100 205 High 1440 Cyan 130000 110 Low 9696

Pink 213600 138 Medium 13920

Orange 134500 245 Very High 3420

Yellow 88500

145 Medium 2800

40200 1840

Red 85600 300 Very High 390 Blue 120000 200 High 1440

White 51800 200 High 345

Total area of layout =1,260,000m

2

Total population =35,291 persons


3

After studying the load forecast, and calculating the load densities in the areas

mentioned before,

In chapter 2, we’ll begin to discuss the adequate building wiring techniques, and

make their calculations, as to say, we’ll begin to distribute electricity in building,

beginning by lighting and sockets loads inside flats, and reaching the riser

calculations and coffree of each building type, so we are able to choose the suitable

cables used in building wiring.

Then, we’ll study the low voltage network and the distribution of the electric power

from medium voltage transformers to the distribution boxes and to the coffrees of

buildings, and thus calculating the suitable cables used in this part of the power

system network, and this is mentioned in chapter 3.

After studying the low voltage network, it’s desired to study the medium voltage

network that supplies this low voltage network, and this is discussed briefly using

some illustrated diagrams in chapter 4.

In chapter 5, we’ll begin to talk about the design, construction and performance of

the high voltage distribution substations, and we’ll mention the layout of the 66/22

KV substation.

Then we’ll discuss the protection schemes of each part of the power system

showing which equipments are used in protection and their constructions, as well as

their theory of operation, and this will be in chapter 6.

Also we’ll talk about the switchgear and its main components, and the different

types of circuit breaker, discussing the theory of operation and principles of

interrupting the arc in each type.

In chapter 7, we’ll have an overview on the street lighting, the types of roads, the

different types of lamps used in the illumination of each type of roads, and the

wattage available of street lighting lamps.

In chapter 8, we’ll have an overview on system grounding, its different schemes

and methods of grounding to the different components and equipments of our system.

After reaching that point, we have described the main steps in planning and

distribution of power system in a developed area, but before ending our project, we’ll

add an additional project talking about the distribution of lighting and socket loads in

a mall. And that will be in chapter 9.

1.6 Summary In planning of a distribution system, we have to take many factors into

consideration. The most important factors are trying to make the system technically

good and reliable, not forgetting to consider the economic point of view.

BUILDING WIRING CALUCLATION

Chapter 2

CHAPTER 2 BUILDING WIRING CALCULATION

4

Chapter 2

BUILDING WIRING CALUCLATION

2.1 Introduction

Light is the prime factor in the human life as all activities of human beings

ultimately depend upon the light. Where there is no natural light, use of artificial is

made. Lighting increases production, reduces fatigue, protecting the health, eyes and

nervous system, and reduces accidents.

In this chapter, we are concerned with studying the electric indoor wiring design

including the lighting design, normal sockets and power sockets design. We are also

concerned with riser calculations and design of the suitable riser required in every

kind of buildings.

The mains wiring is generally built using insulated copper cables. The choice of

conductor material is a compromise among electrical properties, mechanical

properties, and price. From the start, copper has been the material of choice for

household branch circuits.

Aluminum is softer than copper and weaker, and a poorer electrical conductor, so is

not widely used in small sizes for home wiring. Aluminum cable material is

sometimes used (for economical reasons) for thick mains feeder cables coming from

electrical utility to the mains distribution panel.

The ratings of the sub-circuits' miniature circuit breakers (M.C.B) and the main

circuit breaker of the flat or the villa as well as energy meter are selected.

Any house that has been properly wired will have a circuit breaker panel used to

shut circuits off in case they draw too much current. It is the current capacity of

circuit breaker (in amperes) that determines how much current a circuit can supply. In

case of an overload or a short-circuit on that circuit, the breaker trips and

automatically shuts off power to that circuit. Ground fault circuit breakers offer

protection against more than just overloads.

After the load of the flat is being calculated, the diversified estimation of the total

load of the building is made. The buildings are fed from distribution boxes via cables

of suitable sizes, forming a part of the low voltage distribution network. The

distribution boxes are fed from 22 KV/380 V distribution transformers, preferably in

loops, to secure the continuity of supply to the distribution boxes and hence to the

buildings.

Detailed calculations and planning of the 380V low voltage distribution network, the

22KV medium voltage network as well as details of the 66/22KV substation feeding

the area, are presented in the following chapters. Before this, the principles of lighting

and wring are summarized in the following sections.


5

2.2 General Overview on Light

2.2.1 Nature of light:

Various forms of incandescent bodies are sources of light and their light is emitted

by such bodies depending upon their temperature. Energy is radiated into the medium

by a body which is hotter than the medium surrounding it, in the form of

electromagnetic waves of various wavelengths. The velocity of propagation of radiant

energy is approximately 8103 m/sec. The properties and behavior of the radiant

energy depends upon the wavelength. When the temperature is low, the wavelength of

radiant energy will be sufficiently large and the available energy is in the form of heat

waves. As the temperature increases, the wavelength of the radiated energy becomes

smaller and smaller and enter into the range of the wavelength of the light. The

wavelength which can produce the sensation varies from 0.0004 to 0.00075 cm. the

wavelength of the light is expressed in Angstrom unit.

Where 1 Angstrom unit (A.U.) = 810cm.

2.2.2 Basic Definitions

Candela

International unit (SI) of luminous intensity; term evolved from considering a

standard candle, similar to a plumber's candle, as the basis of evaluating the

intensity of other light describe the relative intensity of a source .

Candlepower Distribution Curve

A graphical representation of the distribution of light intensity of a lamp or

luminaire.

Illumination (E)

The quantity of light (measured in foot-candles, Lux, etc) at a point on a

surface.

Inverse Square Law

Formula stating that illumination at a point on a surface varies directly with

the intensity of a point source, and inversely as the square of the distance between

the source and the point; it illustrates how the same quantity of light flux is

distributed over a greater area as the distance from the source to the surface is

increased.

Light Loss Factor

The product of all considered factors that contribute to a lighting system's

depreciated light output over a period of time, including dirt and lamp lumen

depreciation.

Lumen

The international unit of luminous flux or quantity of light.


6

Luminaries

A complete lighting unit consisting of a lamp (or lamps) together with the

parts designed to distribute the light position and protect the lamps, and connect

them to the power supply. This is sometimes referred to as a "fixture".

Lamp efficiency

It is the amount of output lumen per watt.

Lux (lumen/m²)

SI (international system) unit of illumination. One lumen uniformly distributed

over an area of one square meter.

Mounting Height

Distance from the bottom of the fixture to either the floor or work plane,

depending on usage.

Spacing to Mounting Height Ratio

Ratio of fixture spacing (distance apart) to mounting height above the work

plane. Sometimes it is called spacing criterion. A normal range is 1 1.5.

2.2.3 Requirements of a good lighting scheme:

A good lighting scheme should fulfill the following:

1. Provide adequate illumination.

2. Provide uniform illumination all over the working plan.

3. Provide light of suitable color.

4. Avoid glare and hard shadows.

2.2.4 Factors affecting the illumination and wattage of a certain lamp:

Utilization factor (U.F): (0.2 0.6)

It is the ratio of the lumen actually received to the total Lumens emitted by the

source, it depends on:

a. Room dimensions.

b. Color of the walls.

c. Type of lighting scheme.

Maintenance factor (M.F):

It is the ratio between illuminations under normal working conditions to the

illumination when everything is clean. It depends on the rate of cleaning.

M.F = 0.8 for houses.

= 0.3 for streets.

= 0.6 0.7 for schools and shopping centers.

Waste factor:

The ratio between the resultant illuminations due to more than one luminaire to

the summation of their illumination when they work individually. Waste factor is


7

less than unity due to the loss when a place is illuminated by more than one source

due to overlapping.

Reflection factor:

Due to the fact that light reflected by an angle of incidence when impinged on a

surface.

Room index (k):

It is a factor that depends on the dimension of the room. It equals the ratio

between the product of length (L) and breadth (W) of the room to the product of

the mounting height (H) and the summation of the length and breadth of that room.

K = )(*

*

WLH

WL

Generally K varies from 0.6 to 5.0

2.3 Types of lighting schemes

Lighting schemes maybe classified as:

2.3.1 Direct Lighting

It’s the most commonly used type of lighting schemes. In this type of lighting, the

light from the source falls directly on the object or the surface to be illuminated. In

this lighting scheme, more than 90 % of total light flux is made to fall directly on the

working plane with the help of reflectors, shades and globes. It’s important to keep

lamps and fittings clean, otherwise the decrease in effective illumination due to dirty

bulbs or reflectors maybe amount to 15-25 % in offices and domestic lighting and

more in industrial areas.

Although direct lighting is most efficient but it causes hard shadows and glare.

It’s mainly used for industrial and general outdoor lighting.

2.3.2 Semi-direct Lighting

This system utilities luminaries which send most of the light downwards directly

on the working plane but a considerable amount reaches the ceiling and walls. The

deviation is usually 70 % downwards and 30 % upwards.

Such systems are best suited to rooms with high ceilings where high levels of

uniformly distributed illumination desirable. Glare is avoided by using diffusing

globes which improve the brightness of the working plane.

2.3.3 Indirect lighting

In this form of lighting, light doesn’t reach the surface directly from the source,

but indirectly by diffuse reflection. Lamps are either placed behind a cornice or in

suspended opaque bowels. The division is usually 10 % downwards and 90 %

upwards.


8

One of the main characteristics of indirect lighting is that it provides shadow-less

illumination which is very useful for drawing offices, composing rooms, and in

workshops. It’s also used for decoration purposes in cinemas, hotels and theaters.

2.3.4 Semi-indirect lighting

In this system, the light partly received by diffuse reflection and partly direct from

the source. Most of light is directed upwards to the ceilings for diffuse reflection and

the rest reaches the working plane. The division is usually 25 % downwards and 75 %

upwards.

It’s mainly used for indoor lighting decoration purpose.

2.3.5 General lighting

In this system, such illumination are employed which have almost equal light

distribution downwards and upwards.

2.4 Artificial sources of light

The various methods of producing light by electricity are:

1. By arc: By establishing an arc between carbon electrodes.

2. Incandescence of heated filament:

Where an electric current is passed through a filament of thin wire placed in

vacuum or an inert gas. The current generates enough heat to raise the temperature of

filament to luminosity.

3. Glow discharge:

Operate by ionization of gas. The color and intensity of light emitted depend

on the nature of the gas or vapor.

2.4.1 Arc lamps

The various forms of arc lamps are:

a) Carbon arc lamps

b) Flame arc lamps

c) Magnetic arc lamps

2.4.1. a Carbon arc lamps

Two hard carbon rods are placed and connected to a D.C. supply of not less

than 45 volts.

The source of light is incandescent electrode.

The arc is maintained by the transfer of carbon particles from one rod to the

other rod.

White light is produced.

A series resistance is used in stabilizing the arc.

The luminous efficiency of the lamp is 12 lumens / watt.

Used in cinemas projectors.


9

2.4.1.b Flame arc lamps

The principle of operation is similar to that of carbon arc lamps.

It consists of carbon electrodes which are cored and filled with 5-15 % flame

material (fluoride) and 85-95 % carbon.

Different flame materials produce different colors.

The colors produce strain on eyes and do not appeal to eyes. Therefore, they

are replaced by discharge lamps.

The luminous efficiency of such lamp is 8 lumens / watt.

2.4.1.c Magnetic arc lamps

Such lamp has positive electrode made of copper and negative electrode made

of magnetic oxide of iron.

It’s rarely used.

The arc is struck in similar ways as in case of carbon lamp.

2.4.2 Incandescent electric lamps

It consists of a fine wire of a high resistance metal placed in a glass bulb and

heated to luminosity by passage of current through it.

At low temperature, the wire radiates heat energy due to heating; it radiates heat

as well as light energy.

The higher the temperature of the wire results in a higher light energy radiated.

Properties of ideal material for filament lamps

High melting temperature

Low vapour pressure

Higher specific resistance

Low temperature coefficient

There are two types of incandescent lamps

a) Vacuum lamps

b) Gas filled lamps

2.4.2.a Vacuum lamps

Consists of a glass globe completely evacuated and a fine filament in it.

The purpose of vacuum is to prevent loss of heat from filament to bulb. And

also to prevent oxidation of the filament.

The highest temperature in a vacuum lamp is limited to 2100 °C.

2.4.2.b Gas filled lamps

A metal filament can work in an evacuated bulb up to 2000 °C without

oxidation.

To get higher efficiency, it’s necessary to raise the temperature more than

2000 °C. This can be achieved by filling the bulb with an inert gas (argon)

with a small amount of nitrogen to reduce the possibility of arcing.

Introduction of inert gases enables the temperature to rise to about 2500 °C.

It’s used for flood lights of buildings, projectors and motor car headlights.


10

Important characteristics of incandescent lamps

o They are very inefficient producers of light as less than 10 % of the wattage

goes to produce light, while the remainder is heat.

o Principle advantage is the low cost.

o It starts instantly.

o It has a cheap dimming.

o It has a good warm color.

2.4.3 Discharge lamps

They are superior to metal filament lamps.

Light is obtained by applying an electric potential difference, gas gets ionized and

an electric current flows and the tube is filled with luminous discharge.

The color is obtained and depends upon the nature of the gas or vapour used.

There are two types of discharge lamps:

1) Those which give light of the same colour as produced by the discharge

2.4.3.a Sodium vapor lamps

Consists of a bulb containing a small amount of metallic sodium neon gas and

two sets of electrodes connected to a pin type base.

The major application is for high ways and general outdoor lighting.

Its ratings are 45, 60, 85 and 140 watts and have average life time of about

3000 hours.

There are two types of sodium vapor lamps which are:

- High pressure sodium vapor lamps

- Low pressure sodium vapor lamps

2.4.3.b High pressure mercury vapor lamps

It consists of two bulbs, an arc tube containing the electric discharge and

houses three electrodes.

There are two main electrodes and an auxiliary starting electrode.

When supply is switched, an initial discharge is established in argon gas

between one of the main electrodes and the auxiliary electrode and then in

argon between the two main electrodes.

The produced heat is sufficient to evaporate mercury; the operation takes

about 5-7 minutes.

Emitted light is greenish-blue light and true reddish is not possible as there is

complete absence of red light from radiations and red objects appear black.

Its efficiency is about 40 lumens / watt, and lamps are produced in 250 and

400 watt for use on 200-250 a.c. voltage supplies.

Applications of mercury vapor lamps

Street lighting.

Industrial lighting where high illumination level is required and reddish light

is not important.


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2.4.3.c Neon lamps

It belongs to the cold cathode lamps.

It consists of a glass bulb filled with neon gas with small amount of helium.

It gives orange-pink colored light.

If helium gas is used in place of neon, white pink light is obtained.

Electrodes are of pure iron and placed few millimeters apart.

High resistance is used to prevent arcing.

Its efficiency is 15 lumens / watt.

Applications of neon lamps:

It’s used as indicator lamps.

It’s used in advertising.

2) Those which use the phenomena of fluorescence and are known as fluorescent

lamps.

2.4.3.d Fluorescent lamps

It consists of a long glass tube internally coated with fluorescent powder.

The glass tube contains a mixture of inert gas (argon) and mercury vapour.

A choke coil is in the circuit to limit current and provide a voltage impulse for

starting.

The lamp has starter which acts as a switch.

The efficiency of the lamp is about 40 lumens / watt and it has an average life

time of about 4000 hours.

Advantages of fluorescent lamps:

Efficiency is much higher than incandescent lamps.

It produces less heat radiations.

It’s of relatively large size and low surface brightness.

2.4.3.e Compact Fluorescent Lamps (CFL)

It is a new and advanced lighting technology

More efficient than incandescent lamps

CFL use 70 - 75% less energy than their incandescent equivalents. When

replacing a 100 watt incandescent lamp a 28 watt CFL is used.

CFL last approximately 10,000 hours, which is 10 to 13 times the life of an

incandescent lamp (expected life approximately 750 hours).

Compact fluorescents are most cost-effective when used at least 2-3 hours per

day.

Although CFL may appear different than the common incandescent, they fit

most standard fixtures found in homes today. The screw-in base is the same on

both lamps.

The typical incandescent lamp wastes 90% of the energy it uses, producing

heat rather than light.

CFL will provide the same amount of light (or lumens) at a fraction of the

electricity used.


12

2.5 Building wiring calculations

2.5.1 Lighting loads calculations

a) Lux's:

Type Lux

Stairs 50

Saloon 150

Bedrooms 120

Kitchen 300

Bathroom 300

b) Determine room factor (Ri) from tables according to the room dimensions.

Example: kitchen (4.7m*3.6m*2.7m). Ri=G type.

c) Determine utilization factor (u) for the type you choose from tables.

Example: kitchen (uᵍ) ceiling=75%, wall=50%. uᵍ=0.41.

d) Choose maintenance factor (m).

For regular maintenance: (0.76 to 1).

For irregular maintenance: (0.66 to 0.75)

e) Using : 𝑁 =𝐸∗𝐴

𝑢∗𝑚∗𝜂∗𝑃

Where:

N=number of lamps.

E=needed Lux.

A=room area.

U=utilization factor.

η= Lamp efficiency (lumen/watt).

For incandescent lamp:

Rating: 25, 40, 50 , 60 , 80 , 100 ,120,200 Watt.

Power factor = 1.

η=80 lumen/watt.

For fluorescent lamp:

Rating: 20, 40 Watt.

Power factor = 0.8.

η=20 lumen/watt.


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2.5.2 Socket Loads

4.5.2.a Normal sockets (N.S.)

They have different ratings, which can be used such as 2A, 5A,10A the ratings of

2A,5A, can be used for bedrooms, entrance, balcony, which requires low electrical

sets as T.V, radio and small electric fans...etc.

In general we are going to use only the 2A sockets in all the rooms since this is

more practical.

4.5.2.b Power sockets (P.S.)

Sometimes we need some sockets to be used for special purposes like: full

automatic washing cloth machines, air conditions, water heaters, dish washers,

electric ovens and toasters. Such sockets are called power sockets and they require

higher current rating and taking into consideration the starting period which increases

the delivered current to a value higher than normal operation.

To estimate the socket load for certain domestic units the following are to be

considered:

a) Generally there are 2-5 sockets in the room.

b) Generally there are 5-8 normal sockets on a line.

c) Referring to the IEC standard specification, the ratings of sockets are:

M.C.B. rating for normal socket = 10 A

M.C.B. rating for power sockets = 16 A. or 25 A.

d) Calculate the normal socket loads on a line is according to the formula:

Socket load on a line = 100% of largest normal socket rating on the line +

(20%) of ratings of other normal sockets.

e) Each power socket has its own line.

f) To make calculations more exact, we should expect the loads to be used and

their power like:

Radio cassette : 40w, 0.182 A

T.V set: 65 w, 0.3 A

Video: 30w, 0.137 A

Vacuum cleaner: 800w, a p.f of 0.85 , 4.7 A

fans :200w, a p.f of 0.85, 1.069 A

Shaving Machine: 150w, 0.7 A

Hair dryer: 600w, a p.f of 0.85, 3.2 A

Small fridge to be placed in the bedroom: 80w, a p.f of 0.85, 0.43 A

Fridge :160w, p.f of 0.85, 0.86 A

Kitchen machine :600w, p.f of 0.85, 3.2 A

Water Heater:1500w, 6.82 A

Normal washing machines: 1500w, p.f of 0.9, 7.57 A.

Iron: 1000w, 4.64 A.

Sound system: 800w, 3.64 A

Air Conditioner: 2.25 Hp, p.f. 0.9,8.477 A


14

2.5.3 Riser calculations

The riser is cable, which passes upward in each building for transmitting the

electric power from the coffree of the building to each unit of this building, in other

words, it starts from the fuse at the bottom of the house to the highest flat.

It is a three phase cable made usually of copper and has a number of outputs

equals to the number of floors; the output of riser is connected to the fuses which

feeds this floor.

Riser may be one cable or double cable depending on the height of the house, the

number of flats and on the load of each flat.

When choosing the riser we follow the next steps:

a) Calculating the KVA of the flat before diversification and use to determine the

suitable diversification curve.

b) We have two methods to get the diversified KVA of the flat:

i. Using the total number of flats in the building to get the diversified KVA

of the flat. Multiply this diversified KVA by the number of flats in the

building to get the total KVA of the building. Dividing this KVA by

380 3 we get the current that flows in the riser.

ii. Using the total number of flats on each phase to get the diversified KVA of

the flat. Multiply this diversified KVA by the number of flats on the phase

to get the total KVA per phase. Dividing this KVA by 220 we get the

current that flows in the riser.

c) Assuming that the riser must never be loaded by more than 80% of its current

capacity, we can get the current capacity of the riser by dividing the current

obtained in the last step by 0.8.

d) By knowing the value of the current capacity and using the tables of cables

attached in the appendix we can get the c.s.a of the riser and also the rating of

the fuse used for protection. In general 3-ph risers that are used are of the

following sizes: 10 mm², 16mm², 25mm², 50mm² and 70mm².

e) Other services loads like water pumps, elevators (for buildings more than 6

floors) and stairs lighting are to be considered in our calculations.

f) A fuse is added for protection.

2.6 General points to be considered in the design:

1. In distribution of loads among light circuits or socket circuits we should

connect the rooms that are next to each other on the same sub circuit to avoid

crossing between connections. Also it is recommended that the circuits of the

same type are equally loaded.

2. Diversity factor between the sockets on the same line depends on some factors

like the area of the flat, the larger the area the smaller the diversity factor used.

3. In calculating the required amount of light for the shaving mirror in the

bathroom we consider the recommended lux to be half of that required for the

bathroom yet the area is the same area of the bathroom. We use incandescent

lamps for the shaving mirror.

4. Flats of area less than 90 m² are considered as youth housing thus single phase

energy meters are used in them.


15

5. The distribution of flats among riser phases is done in a way to make voltage

drop on each phase exactly equal to other phases.

6. Single phase energy meters are of ratings 20A and 40A. Three phase energy

meters are 3×20A, 3×25A, 3×40A and 3×80A.

7. For the c.s.a of the neutral conductor, we follow the Egyptian Electric Code

(EEC) which states " If the c.s.a of the phase conductor is less than or equal 16

mm²then the neutral conductor is of the same c.s.a as the phase conductor. If

the phase conductor is of c.s.a less than 35 mm²then the neutral conductor is of

c.s.a equal to the one preceding the concerned phase conductor. If the c.s.a of

the phase conductor is more than or equal 50 mm² then the c.s.a of the neutral

conductor is half of the concerned phase conductor.

8. In general all our distribution of loads among the lines or the phases we must

care that the loads are almost balanced as much as we can to avoid the

unbalanced operation.

9. Low voltage fuses ratings are as follows:

2, 4, 6, 8, 10, 16, 20, 25, 32, 35, 40, 50, 63, 80, 100,125 and 160 according to

ABB pocket book (switchgear manual), 8th edition.

2.7 Calculation of loads for flats & villas:

2.7.1 Flat type (A)

a) Lighting:

Line room length width Lux Area u ƞ number of lamps lamps lamps wattage power factor

installed wattage

lamp current line 1 line2 line3 line4

1 Entrance 3.55 1.7 50 6.035 0.49 20 0.384885204 1 100 1 100 0.454545455 0.454545

1 Entrance Hall 1.7 4.35 50 7.395 0.49 20 0.786033163 2 60 1 120 0.545454545 0.545455

4 Inner Hall 5.5 2.5 50 13.75 0.49 20 1.461522109 2 60 1 120 0.545454545

0.545455

2 Saloon 4.8 11.95 150 57.36 0.49 20 18.29081633 20 60 1 1200 5.454545455 2.75 2.75

2 Balcony 1 3.25 5.8 50 18.85 0.49 20 1.202168367 2 100 1 200 0.909090909

0.909091

3 Bedroom 1 4 4.4 120 17.6 0.49 20 4.489795918 6 60 1 360 1.636363636

1.636364

3 Balcony 4 1.5 1.5 50 2.25 0.49 20 0.239158163 1 60 1 60 0.272727273

0.272727

3 Bathroom 2 2.3 2.1 300 4.83 0.35 80 1.6171875 2 40 0.8 80 0.454545455

0.454545

4 Kitchen 4.7 3.7 300 17.39 0.41 80 4.970464939 6 40 0.8 240 1.363636364

1.363636

4 Balcony 3 3 1.15 50 3.45 0.49 20 0.366709184 1 60 1 60 0.272727273

0.272727

4 Bathroom 1 1.45 3 300 4.35 0.35 80 1.456473214 2 40 0.8 80 0.454545455

0.454545

3 Bedroom 2 4.3 3.9 120 16.77 0.49 20 4.278061224 6 60 1 360 1.636363636

1.636364

3 Balcony 2 4.1 2.2 50 9.02 0.49 20 0.958758503 1 60 1 60 0.272727273

0.272727

4 Bedroom 3 4.9 3.8 120 18.62 0.49 20 7.125 6 40 1 240 1.090909091

1.0909

4 Bedroom 3-Closte 2.1 1.9 120 3.99 0.49 20 1.017857143 1 60 1 60 0.272727273

0.272

4 Bathroom 3 2 1.9 300 3.8 0.35 80 1.272321429 2 40 0.8 80 0.454545455

0.454

205.46 Sum 3.75 3.659091 4.272727 4.453264

CB rating 4.5 4.390909 5.127273 5.343916

closest CB 10 10 10 10


17

b) Normal & Power Sockets:

line Type Current C.B rating MCB C.S.A

line 1 Lighting 3.75 4.5 10 3*2.5 mm²

line 2 Lighting 3.66 4.392 10 3*2.5 mm²

line 3 Lighting 4.273 5.1276 10 3*2.5 mm²

line 4 Lighting 4.453 5.3436 10 3*2.5 mm²

line 5 Normal sockets 4.4 5.28 10 3*4 mm²

line 6 Normal sockets 4 4.8 10 3*4 mm²





line 11 AC 8.477 10.1724 25 3*6 mm²

line 12 AC 8.477 10.1724 25 3*6 mm²

line 13 AC 8.477 10.1724 25 3*6 mm²

line 14 AC 8.477 10.1724 25 3*6 mm²

line 15 Washing machine 7.57 9.084 16 3*4 mm²

line 16 Dryer 7.57 9.084 16 3*4 mm²

line 17 Water Heater 7.57 9.084 16 3*4 mm²


Power sockets calculations:

Type Current Calculations

Air conditioner (2.25 HP): 𝑰𝑨𝑪 =

𝟐.𝟐𝟓∗𝟕𝟒𝟔

𝟐𝟐𝟎∗𝟎.𝟗= 𝟖.𝟒𝟕𝟕 𝑨 (normal current)

=8.477×1.25=10.59 A (Starting current)

Water Heater: 𝑰𝑾𝑯 =𝟏𝟓𝟎𝟎

𝟐𝟐𝟎 ∗ 𝟎.𝟗= 𝟕.𝟓𝟕 𝑨

Washing machine: 𝑰𝑾𝑴 =𝟏𝟓𝟎𝟎

𝟐𝟐𝟎 ∗ 𝟎.𝟗= 𝟕.𝟓𝟕 𝑨

Dryer: 𝑰𝑫𝒓𝒚𝒆𝒓 =𝟏𝟓𝟎𝟎

𝟐𝟐𝟎 ∗ 𝟎.𝟗= 𝟕.𝟓𝟕 𝑨


18

c) KVA calculation:

Σ light =3.75+3.659091+4.272727+4.453264= 16.13 A.

Σ Normal sockets=4.4+4+ (3.6×4) =22.8 A.

Σ Power sockets= (8.477×4) + (7.57×2) + (7.57×2) =64.188 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[16.13+22.8+64.188] =72.6 A.

∴ 𝑲𝑽𝑨𝒇𝒍𝒂𝒕=72.6×220=15.9 KVA.

∴ 𝑰𝒎𝒂𝒊𝒏 𝒑𝒉𝒂𝒔𝒆 =72.6

3= 24.2 𝐴.

Then,

M.C.B=32 A (3 phase).

C.S.A =5×16 mm².

Meter used = 40A Three phase meter.

Phase balance:

Phase R Phase S Phase T

Line Current Line Current Line Current

Lighting L1 3.75 L3 4.273 L4 4.453

L2 3.659

Normal Sockets L5 4.4 L7 3.6 L9 3.6

L6 4 L8 3.6 L10 3.6

Power Sockets

L11 8.477 L13 8.477 L16 7.57

L12 8.477 L14 8.477 L17 7.57

L15 7.57 L18 7.57

Sum

32.763

35.997

34.363

d) Riser calculation: We will have 24 building of this type, each of 12 apartments in 6 floors.

From diversity graph, we get the diversified KVA of flat.

∴ 𝑲𝑽𝑨𝒇𝒍𝒂𝒕(𝒅𝒊𝒗𝒆𝒔𝒊𝒇𝒊𝒆𝒅) =7.9 KVA.

∴ 𝑲𝑽𝑨𝑩𝒖𝒍𝒊𝒅𝒊𝒏𝒈=7.9×12=94.8 KVA.

∴ 𝑰𝑹𝒊𝒔𝒆𝒓 =94.8∗103

380 3 =144.03 A.

Then, Fuse=160 A (3 phase).

C.S.A =3×70+35+35 mm².


19

Fig 2.1 Distribution of lighting in flat type (A).


20

Fig 2.2 Distribution of Sockets in flat type (A).


21

²

² ²

²

² ² ² ² ² ²²²²²²²

² ² ²

Fig 2.3 Distribution board in flat type (A).


22

Fig 2.4 Riser diagram in flat type (A).

²

²

²

2.7.2 Flat type (B)

a) Lighting:

Line room length width Lux Area u ƞ number of

lamps lamps

lamps wattage

power factor

installed wattage

lamp current line 1 line2

2 entrance 1.35 1.4 50 1.89 0.49 20 0.20089286 2 60 1 120 0.545454545

0.5454

2 Saloon 6.35 3.85 150 24.4475 0.49 20 7.79575893 8 60 1 480 2.181818182

2.1818

2 bed room 1 4.05 3.5 120 14.175 0.49 20 3.61607143 4 60 1 240 1.090909091

1.0909

2 balcony 1 2 3.5 50 7 0.49 20 0.74404762 1 60 1 60 0.272727273

0.2727

2 bed room 2 5.25 3.45 120 18.1125 0.49 20 4.62053571 5 60 1 300 1.363636364

1.3636

1 bed room 3 5.45 4.2 120 22.89 0.49 20 5.83928571 6 60 1 360 1.636363636 1.636

1 balcony 2 1.1 1.1 50 1.21 0.49 20 0.12861395 1 60 1 60 0.272727273 0.27

1 kitchen 2.6 3.5 300 9.1 0.41 80 2.60099085 3 40 0.8 120 0.681818182 0.6818

1

0.7 0.7

1 small bathroom 2.6 1.1 300 2.86 0.35 80 0.95758929 1 40 0.8 40 0.227272727 0.227

1

1 1 25 0.8 25 0.142045455 0.142

1

0.7 0.7

1 big bathroom 2.6 1.75 300 4.55 0.35 80 1.5234375 2 40 0.8 80 0.454545455 0.45455

1

1 1 25 0.8 25 0.142045455 0.142

1

0.7 0.7

1 corridor 1.1 4.8 50 5.28 0.49 20 0.56122449 1 60 1 60 0.272727273 0.273

111.515

Sum 5.92635 5.4544

CB rating 7.11162 6.54528

closest CB 10 10


24


Line Type calculations current Column1 C.B C.S.A

line 1 Lighting - 5.92 - 10 3×2.5 mm²

line 2 Lighting - 5.45 - 10 3×2.5 mm²

line 3 normal sockets 2+.2(6x2) 4.4 5.28 10 3×4 mm²



line 6 ID55 (1500/220x0.9) 7.57 9.084 16 3×4 mm²

line 7 AC 2.25x746/(220x0.9) 8.477 10.1724 25 3×6 mm²

c) KVA calculation:

Σ light =5.92+5.45= 11.37 A.

Σ Normal sockets=4.4×3 =13.2.

Σ Power sockets=0.5× [8.477+7.57] =8.0235 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[11.37+13.2+8.0235] =22.8 A.

∴ 𝑲𝑽𝑨𝒇𝒍𝒂𝒕=22.8×220=5 KVA.

Then,

M.C.B=32 A (Single phase).

C.S.A =3×10 mm².

Meter used = 40A Single phase meter.




∴ 𝑲𝑽𝑨𝑩𝒖𝒍𝒊𝒅𝒊𝒏𝒈=1.9×24= 45.6 KVA.

∴ 𝑰𝑹𝒊𝒔𝒆𝒓 =45.6∗103

380 3 =69.28 A.

Then,

Fuse=80 A (3 phase).

C.S.A =3×25+25+25 mm².


25

Fig 2.5 Distribution of lighting in flat type (B).

Fig 2.6 Distribution of Sockets in flat type (B).


26

²

²

²

Fig 2.7 Distribution board in flat type (B).

Fig 2.8 Riser diagram in flat type (B)

² ²

² ² ²

²

² ²

2.7.3 Flat type (C)

a) Lighting:

Line room length width Lux Area u ƞ number of

lamps lamps

lamps wattage

power factor

installed wattage

lamp current line 1 line2

1 entrance 2.06 1.3 50 2.678 0.49 20 0.28465136 2 60 1 120 0.545454545 0.5454

1 reception 7.8 5.35 150 41.73 0.49 20 13.3067602 14 60 1 840 3.818181818 3.818

1 trace 2.1 4.7 50 9.87 0.49 20 1.04910714 2 60 1 120 0.545454545 0.5454

1 bed room 1 3.6 5 120 18 0.49 20 4.59183673 5 60 1 300 1.363636364 1.3636

1 bathroom 1 1.7 2.7 300 4.59 0.35 80 1.53683036 2 40 0.8 80 0.454545455 0.4545

1

1 1 25 0.8 25 0.142045455 0.142

1

0.7 0.7

2 entrance bathroom 1 1.7 1.9 50 3.23 0.49 20 0.34332483 1 60 1 60 0.272727273

0.2727

2 bed room 2 3.7 3.7 120 13.69 0.49 20 3.49234694 5 60 1 300 1.363636364

1.3636

2 corridor 1.05 3.82 50 4.011 0.49 20 0.42633929 1 60 1 60 0.272727273

0.2727

2 bathroom 2 1.7 2.7 300 4.59 0.35 80 1.53683036 2 40 0.8 80 0.454545455

0.4545

2

1 1 25 0.8 25 0.142045455

0.142

2

0.7

0.7


0.2727

2 bedroom 3 3.9 4.78 120 18.642 0.49 20 4.75561224 5 60 1 300 1.363636364

1.3636


0.2727

2 bathroom 3 2.1 1.3 300 2.73 0.35 80 0.9140625 1 40 0.8 40 0.227272727

0.227

2

1 1 25 0.8 25 0.142045455

0.142

2

0.7

0.7

2 kitchen 3.7 2.6 300 9.62 0.41 80 2.7496189 3 40 0.8 120 0.681818182

0.6818

2

0.7

0.7

138.46

sum 7.5689 7.5653

C.B rating 9.08268 9.07836

Closet C.B 10 10


28


Line Type calculations current Column1 C.B C.S.A

line 1 Lighting - 7.57 - 10 3*2.5 mm²

line 2 Lighting - 7.57 - 10 3*2.5 mm²

line 3 normal sockets 2+.2(6x2) 4.4 5.28 10 3*4 mm²




line 7 ID55 (1500/220x0.9) 7.57 9.084 16 3*4 mm²

line 8 ID55 (1500/220x0.9) 7.57 9.084 16 3*4 mm²

line 9 AC 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mm²

line 10 AC 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mm²

c) KVA calculation:

Σ light =7.57+7.57= 15.14 A.

Σ Normal sockets=4.4+3.6+3.6+4.4 =16 A.

Σ Power sockets=0.5× [2×8.477+2×7.57] =16.047 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[15.14+16+16.047] =33 A.

∴ 𝑲𝑽𝑨𝒇𝒍𝒂𝒕=33×220=7.263 KVA.

Then,


C.S.A =3×16 mm².





∴ 𝑲𝑽𝑨𝑩𝒖𝒍𝒊𝒅𝒊𝒏𝒈=2.8×24= 67.2 KVA.

∴ 𝑰𝑹𝒊𝒔𝒆𝒓 =67.2∗103

380 3 =102.1 A.

Then,

Fuse=160 A (3 phase).

C.S.A =3×70+35+35 mm².


29

Fig 2.9 Distribution of lighting in flat type (C).

Fig 2.10 Distribution of Sockets in flat type (C).


30

Fig 2.11 Distribution board in flat type (C).

² ²

² ²

²

² ² ² ² ² ²


31

Fig2.12 Riser diagram in flat type (B).

²

²

²

2.7.4 Flat type (D)

a) Lighting:

room Lux Area u ƞ number of lamps lamps lamps wattage power factor installed wattage lamp current line 1 line 2 line 3 line 4 line5

Door entrance 50 3.9 0.49 20 0.622 1 40 1 40 0.181818

0.182

Saloon 150 82 0.49 20 15.69 16 100 1 1600 7.272727 3.637 3.637

Hall entrance 50 7 0.49 20 0.744 1 60 1 60 0.272727

0.273

Kitchen 300 17.85 0.41 80 5.102 6 40 0.8 240 1.363636

1.364

Path 1 50 3.25 0.49 20 0.345 1 60 1 60 0.272727

0.273

Path 2 50 12 0.49 20 1.276 2 60 1 120 0.545455

0.545

Path 3 50 4.75 0.49 20 0.505 1 60 1 60 0.272727

0.273

Living room 150 20.4 0.49 20 3.903 4 100 1 400 1.818182

1.818

Bathroom 1 300 4.42 0.35 80 1.48 2 40 0.8 80 0.454545

0.455

Bathroom 2 300 4.9 0.35 80 1.641 2 40 0.8 80 0.454545

0.455

Bathroom 3 300 5.2 0.35 80 1.741 2 40 0.8 80 0.454545

0.455

Nanny room 120 5.5 0.49 20 1.403 2 60 1 120 0.545455

0.545

Nanny's bath 200 2.6 0.35 80 0.58 1 40 0.8 40 0.227273

0.227

Bedroom 1 120 20.4 0.49 20 5.204 6 60 1 360 1.636364

1.636

Bedroom 2 120 18.4 0.49 20 4.694 5 60 1 300 1.363636

1.364

Extension 50 5.66 0.49 20 0.602 1 60 1 60 0.272727

0.273

Bedroom 3 120 20 0.49 20 5.102 6 60 1 360 1.636364

1.636

Balcony 50 6 0.49 20 0.638 1 60 1 60 0.272727

0.273

244.2

Sum 3.637 3.909 3.182 4.409 4

CB rating 4.364 4.691 3.818 5.291 4.8

closest CB 10 10 10 10 10


33


Line Type Current C.B M.C.B C.S.A

line 1 Lighting 3.6365 4.3638 10 3*2.5 mm²

line 2 Lighting 4.1825 5.019 10 3*2.5 mm²

line 3 Lighting 2.909 3.4908 10 3*2.5 mm²

line 4 Lighting 4.411 5.2932 10 3*2.5 mm²

line 5 Lighting 3.185 3.822 10 3*2.5 mm²









line 14 AC 8.477 10.1724 25 3*6 mm²

line 15 AC 8.477 10.1724 25 3*6 mm²

line 16 AC 8.477 10.1724 25 3*6 mm²

line 17 AC 8.477 10.1724 25 3*6 mm²



line 20 Dryer 7.576 9.0912 20 3*6 mm²

line 21 Washing machine 7.576 9.0912 20 3*6 mm²

c) KVA calculation:

Σ light =3.63+4.183+2.91+4.411+3.185= 18.32 A.

Σ Normal sockets=3.2+ (4.4×3) + (3.6×4) =30.8 A.

Σ Power sockets= (8.477×4) + (7.57×2) + (7.57×2) =64.188 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[18.32+30.8+64.188] =79.3156 A.

∴ 𝑲𝑽𝑨𝒇𝒍𝒂𝒕=79.3156×220=17.4 KVA.


3= 26.4 𝐴.

Then,


C.S.A =5×16 mm².



34

Phase balance:

Phase R Phase S Phase T

Line Current Line Current Line Current

Lighting L1 3.6365 L3 3.182 L5 4

L2 3.91 L4 4.41

Normal Sockets

L6 3.6 L10 3.6 L12 4.4

L7 3.6 L11 4.4 L13 4.4

L8 3.6

L9 3.2

Power Sockets

L18 7.576 L15 8.477 L14 8.477

L19 7.576 L16 8.477 L17 8.477

L20 7.576 L21 7.576

Sum

36.6985

40.122

37.33




∴ 𝑲𝑽𝑨𝑩𝒖𝒍𝒊𝒅𝒊𝒏𝒈=8.2×12=98.4 KVA.

∴ 𝑰𝑹𝒊𝒔𝒆𝒓 =98.4∗103

380 3 =149.5 A.


C.S.A =3×70+35+35 mm².


35

Fig 2.13 Distribution of lighting in flat type (D).


36

Fig 2.14 Distribution of Sockets in flat type (D).


37

Fig 2.15 Distribution board in flat type (D).

²

²

²

²

² ² ² ² ² ² ²

²²²²²²²² ² ² ²


38

Fig 2.16 Riser diagram in flat type (D).

²

²

²

2.7.5 Flat type (E)

Repeated apartments:

a) Lighting:

Line 2 Line 1 Current Total

Wattage (Positions x N lamps x Watt)

Wattage needed

Illumination Type

Area Dimensions Lux Room

8.18 8.18 1800 3x3x200 1764 Incandescent 44.1 5.4*3.7+3.6*6.7 200 Open Salon Living

0.45 0.45 100 1x1x100 77 Incandescent 7.7 2.14*3.6 50 Balcony

0.45 0.45 80 1x2x40 72.216 Florescent 3.54 2.36*1.5 300 Guest's Bathroom

1.82

1.82 320 2x4x40 293.76 Florescent 14.4 4*3.6 300 Kitchen

0.45 0.45 100 1x100 70.8 Incandescent 3.54 1.5*2.36 100 Entrance

2 2 450 3x1x150 439 Incandescent 8.78 1.12*7.84 50 Hallway

1.82

1.82 400 1x4x100 388.8 Incandescent 12.96 3.6*3.6 150 Children's Bedroom

0.27

0.27 60 1x1x60 55.7 Incandescent 5.57 2.36*2.36 50 Room Entrance

Hallway

0.68

0.68 120 1x3x40 113.628 Florescent 5.57 2.36*2.36 300 Children's Bathroom

3.64

3.64 800 2x2x200 790.5 Incandescent 26.35 7.32*3.6 150 Master Bedroom

0.68

0.68 150 1x1x150 124.5 Incandescent 4.15 1.76*2.36 150 Changing Room

0.68

0.68 120 1x3x40 112.2 Florescent 5.5 2.36*2.33 300 Master Bathroom

line2=9.59A line1=11.53A Total

Current=21.12A Total Area

=142.16

6.32A 7.61A Diversified

current

10 10 C.B


40


Normal Socket Lines Calculations For Repeated apartments

Div. Line Current Rating

Number of 5A Sockets

Number of 3A Sockets Normal Sockets

Lines

5.4 0 5 S1

8.2 3 2 S2

7.8 2 3 S3

7.4 1 4 S4

5.4 0 5 S5

7.6 3 1 S6

Power Socket Lines Rating For Repeated Apts

Line Current Rating

Assuming 0.7 p.f

Kwatt Rating

Air Cond.Rating

in Hp

Horse Power needed

10sqm/hp

Air Cond. Coverage

Area

Power Sockets

Lines

14.5 2.24 3 2.2 22 P1

14.5 2.24 3 2.2 22 P2

7.27 1.12 1.5 1.44 14.4 P3

7.27 1.12 1.5 1.3 13 P4

14.5 2.24 3 2.6 26 P5

Repeated Apt CBs And CSAs

CSA MCB Current Line

3x2.5mm2 10 7.61 L1

3x2.5mm2 10 6.32 L2

3x2mm2 10 5.4 S1

3x2mm2 10 8.2 S2

3x2mm2 10 7.8 S3

3x2mm2 10 7.4 S4

3x2mm2 10 5.4 S5

3x2mm2 10 7.6 S6

3x3mm2 15 7.27 P1

3x3mm2 15 7.27 P2

3x6mm2 32 14.5 P3

Ground floor apartment:

a) Lighting:

Line 4 Line 3 Line 2 Line 1 Current Total

Wattage

(Positions x N.lamps

x Watt)

Wattage needed

Illumination Type

Area Width Length Lux Room

0.18 0.18 40 1x1x40 15.25 Incandescent 1.525 1.22 1.25 50 Door 1

4.1 4.1 900 1x6x150 898.4 Incandescent 22.4576 4.64 4.84 200 Salon

0.27 0.27 60 1x1x60 57 Incandescent 5.7112 4.84 1.18 50 Balcony 1

5.45 5.45 1200 1x8x150 1159.6 Incandescent 28.9916 4.84 5.99 200 Dining

0.45

0.45 80 1x2x40 77 Florescent 3.776 2.36 1.6 300 Guest's Bathroom

0.18

0.18 40 1x1x40 37.76 Incandescent 3.776 2.36 1.6 50 Entrance hall

0.36

0.36 80 2x1x40 54.2 Incandescent 5.4208 1.12 4.84 50 Hall 1

0.68

0.68 120 1x3x40 96.3 Florescent 7.08 2.36 3 200 Laundry Room

0.45

0.45 80 1x2x40 82.8 Florescent 4.0592 1.72 2.36 300 Maid's Bathroom

2.05

2.05 360 3x3x40 352.512 Florescent 17.28 3.6 4.8 300 Kitchen

2.27

2.27 500 1x5x100 522.72 Incandescent 17.424 3.6 4.84 150

Children's Bedroom

0.18

0.18 40 1x1x40 15.25 Incandescent 1.525 1.22 1.25 50 Door 2

10.9

10.9 2400 3x4x200 2156.7 Incandescent 53.9176 4.84 11.14 200 Reception

0.27

0.27 60 1x1x60 57 Incandescent 5.7112 4.84 1.18 50 Balcony 2

0.55

0.55 120 3x1x40 62.5 Incandescent 6.2496 1.12 5.58 50 Hall 2

0.9

0.9 200 1x5x40 180.54 Florescent 8.8485 3.47 2.55 300 Master Bathroom

1.36

1.36 300 1x2x150 274.5 Incandescent 9.1516 3.34 2.74 150 Changing Room

2.73

2.73 600 1x4x150 612.6 Incandescent 20.4248 4.22 4.84 150 Master Bedroom

2.73

2.73 600 1x4x150 580.8 Incandescent 19.36 4.84 4 150 Living

0.55

0.55 120 1x3x40 114.2 Incandescent 11.4224 4.84 2.36 50 Balcony 3

8.27 11.35 6.99 10 Sum

5.46 7.49 4.61 6.6 Diversified

current

10 10 10 10 C.B.


42


Normal Socket Lines Calculations For Ground floor Apt.

Div. Line Current Rating

Number of 10A Sockets

Number of 5A Sockets Normal Socket

Lines

10 0 6 S1

18 3 4 S2

15 1 5 S3

11 0 7 S4

10 0 6 S5

15 1 5 S6

Power Socket Lines Calculations For Ground floor Apt.

Current Assuming 0.7 p.f Wattage Power Use Power Sockets Lines

14.5 2.23 3hp Air Cond P1








32.47 5 __ Washer+Dryer P9

Panel 1 Lines

Phase T Phase S Phase R CSA(mm²) MCB Current Lines

6.6

3x2.5 10 6.6 L1

4.61 3x2.5 10 4.61 L2

7.49

3x2.5 10 7.49 L3

5.46 3x2.5 10 5.46 L4

10 3x3 15 10 S1

18

3x4 20 18 S2

15

3x4 20 15 S3

11 3x3 15 11 S4

10

3x3 15 10 S5

15

3x4 20 15 S6

14.5 3x6 32 14.5 P1

14.5 3x6 32 14.5 P2

9.74 3x4 20 9.74 P3

9.74

3x4 20 9.74 P4

14.5 3x6 32 14.5 P5

14.5

3x6 32 14.5 P6

14.5

3x6 32 14.5 P7

14.5

3x6 32 14.5 P8

32.47

3x10 40 32.47 P9

78.57 79.23 84.31

242.11

IT Div0 =46.97A IS Div0 =33.438A IR Div0 =36.518A


43

c) KVA calculation:

∴ 𝑰𝒎𝒂𝒊𝒏=(7.61+6.32)+14.5+0.2[7.27×2+5.4×2+7.8+7.4+8.2+7.6] =39.698 A.

∴ 𝑲𝑽𝑨𝒇𝒍𝒂𝒕=39.698×220=8.733 KVA.

Then,


C.S.A =3×16 mm².





∴ 𝑲𝑽𝑨𝑩𝒖𝒍𝒊𝒅𝒊𝒏𝒈=6.5×10=65 KVA.

∴ 𝑰𝑹𝒊𝒔𝒆𝒓 =65∗103

380 3 =98.757 A.


C.S.A =3×70+35+35 mm².


44

Fig 2.17 Distribution of lighting in flat type repeated (E).


45

Fig 2.18 Distribution of Sockets in flat type repeated (E).


46

Fig 2.19 Distribution of Light in flat type zero floor (E).


47

Fig 2.20 Distribution of Sockets in flat type zero floor (E).

2.7.6 Villa type (A)

Ground Floor:

a) Lighting:

line room length width Lux Area ƞ u lamp type

watt no of lamps

lamps wattage

power factor

installed wattage

lamp current

current line 1 line 2 line 3 line 4 line5 line6

3 villa

entrance1 _ _ 50 225.5 20 0.49 0.2 2255 22 60 1 1320 6 6

6

5 villa

entrance2 _ _ 50 70 20 0.49 0.2 700 12 100 1 1200 5.454545 5.454545

5.45

6 entrance 1 1.06 4.25 50 4.505 20 0.49 0.2 45.05 1 40 1 40 0.181818 0.181818

0.181

6 kitchen1 3.95 4.2 300 16.59 80 0.41 0.0683 339.9291 8 40 0.8 320 1.818182 1.818182

1.818

1 bath1 2.22 3.29 300 7.3038 80 0.35 0.0683 149.654862 3 40 0.8 120 0.681818 1.381818 1.38

4 corridor1 2.22 1.59 100 3.5298 20 0.49 0.2 70.596 1 40 1 40 0.181818 0.181818

0.1818

1 bed room 1 4.88 5.26 150 25.669 20 0.41 0.2 770.064 8 100 1 800 3.636364 3.636364 3.63

5 nani2 3 1.88 150 5.64 20 0.35 0.2 169.2 4 40 1 160 0.727273 0.727273

0.72

5 bath4 1.96 2.46 300 4.8216 80 0.49 0.0683 98.794584 2 40 0.8 80 0.454545 1.154545

1.15

3 corridor4 3.87 1.2 50 4.644 20 0.49 0.2 46.44 1 20 1 20 0.090909 0.090909

0.0909

6 dinning 2 5.22 4.2 200 21.924 20 0.35 0.2 876.96 8 100 1 800 3.636364 3.636364

3.6363

3.636

4 sallon1 a 6.66 3.75 150 24.975 20 0.49 0.2 749.25 8 100 1 800 3.636364 3.636364

2 sallon1 b 9.88 6.19 150 61.157 20 0.49 0.2 1834.716 20 100 1 2000 9.090909 9.090909

9.09

1 stairs 4.8 3.7 100 17.76 20 0.49 0.2 355.2 6 60 1 360 1.636364 1.636364 1.63

9 hall 3.26 9.15 150 29.829 20 0.49 0.2 894.87 18 40 1 720 3.272727 3.272727

2 trace2 4.52 1.42 50 6.4184 20 0.49 0.2 364.952 1 40 1 40 0.181818 0.181818

0.1818

Sum 6.65 9.2718 6.0909 3.8181 7.33 5.636

CB rating 7.98 11.126 7.3090 4.5818 8.80 6.763

closest CB 10 10 10 10 10 10


49


Line Type current MCB CSA

1 light 6.65 10 3*2.5mm²

2 light 9.27 10 3*2.5mm²

3 light 6.09 10 3*2.5mm²

4 light 4.27 10 3*2.5mm²

5 light 7.34 10 3*2.5mm²

6 light 5.64 10 3*2.5mm²

7 Spare

8 Normal sockets 4.4 10 3*4mm²




12 Normal sockets 4 10 3*4mm²

13 Power Socket 7.57 16 3*4mm²

14 Power Socket 7.57 16 3*4mm²

15 Water heater 7.57 16 3*4mm²


17 AC 8.48 25 3*6mm²

18 AC 8.48 25 3*6mm²

19 AC 8.48 25 3*6mm²

20 AC 8.48 25 3*6mm²

c) KVA calculation:

Σ light =6.65+7.27+6.09+4.27+7.34+5.64= 29.92 A.

Σ Normal sockets=4 + (4.4×3) + 4.8 =22 A.

Σ Power sockets= 0.5[(8.48×4) + (7.57×2) + (7.57×2)] =32.1 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[29.92+22+32.1] =65.35 A.

∴ 𝑲𝑽𝑨𝒈𝒓𝒐𝒖𝒏𝒅=65.35×220=14.377 KVA.


3= 21.78 𝐴.

Then,


C.S.A =5×10 mm².

First Floor:

a) Lighting: line room length width Lux Area

lamp type

watt number of

lamps lamps

wattage power factor

installed wattage lamp

current Line 1 Line 2 Line 3 Line 4 Line 5 Line 6

5 trace1 1.18 3.68 50 4.342 0.2 43.42 1 40 1 40 0.182

0.182

5 bedroom1 4.2 4.15 150 17.43 0.2 522.9 6 100 1 600 2.727

2.727

5 bath1 2.16 3.36 300 7.258 0.063 137.8 3 40 0.8 120 0.682

0.682

4 corridor1 2.34 1.76 100 4.118 0.2 82.37 1 40 1 40 0.182

0.182

4 bedroom2 4.82 5.3 150 25.55 0.2 766.4 6 100 1 600 2.727

2.727

4 bath 2 2.88 1.77 300 5.098 0.068 104.4 3 40 0.8 120 0.682

1.382

4 office 1 2.48 2.08 250 5.158 0.068 88.08 3 40 0.8 120 0.682

0.364

4 corridor 2 1.1 8.03 50 8.833 0.2 88.33 2 40 1 80 0.364

2.727

3 bedroom 3 5.3 4.15 150 22 0.2 659.9 6 100 1 600 2.727

2.727

6 bath 3 5.22 1.86 300 9.709 0.068 198.9 5 40 0.8 200 1.136

1.364

6 dressing room1

5.2 2.88 150 14.98 0.2 449.3 4 100 1 400 1.818

1.818

2 stairs 4.72 4.8 100 22.66 0.2 453.1 6 100 1 600 2.727

2.727

1 living room 5.6 6.08 200 34.05 0.2 1362 10 150 1 1500 6.818 6.818

6 bedroom 4 5.34 4.88 150 26.06 0.2 781.8 8 100 1 800 3.636

3.636

3.636

1 trace 2 5.22 1.06 50 5.533 0.2 55.33 2 40 1 80 0.364 0.364

3 trace 3 6.08 1.2 50 7.296 0.2 72.96 2 40 1 80 0.364

0.364

Sum 7.182 2.727 6.727 7.382 3.591 6.818

CB rating 8.6181 3.2727 8.0726 8.8580 4.3089 8.1817

closest

CB 10 10 10 10 10 10


51


line type current MCB CSA

1 light 7.18 10 3*2.5mm²

2 light 2.73 10 3*2.5mm²

3 light 6.73 10 3*2.5mm²

4 light 7.38 10 3*2.5mm²

5 light 6.82 10 3*2.5mm²

6 light 6.82 10 3*2.5mm²

7 light spare 10 3*2.5mm²

8 Normal Sockets 4.4 10 3*4mm²






14 Power Sockets 7.57 20 3*6mm²




18 AC 8.48 25 3*6mm²


20 AC 8.48 25 3*6mm²

d) KVA calculation:

Σ light =7.18+2.73+6.73+7.38+6.82+6.82= 37.66 A.

Σ Normal sockets= (4.4×4) + (3.2×2) =24 A.

Σ Power sockets= 0.5[(8.48×2) + (7.57×4) + (7.57)] =27.405 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[37.66+24+27.405] =62.34 A.

∴ 𝑲𝑽𝑨𝑭𝒊𝒓𝒔𝒕=62.34×220=13.716 KVA.


3= 20.78 𝐴.

Then,


C.S.A =5×10 mm².


52

Garage:

line current MCB CSA

1 1.818 10 3*2.5mm²

2 2.727 10 3*2.5mm²

3 2.045 10 3*2.5mm²

4 2.045 10 3*2.5mm²

5 2.727 10 3*2.5mm²

6 0.682 10 3*2.5mm²

7 7.57 20 3*6mm²

8 7.57 20 3*6mm²

9 7.57 20 3*6mm²

10 7.57 20 3*6mm²

KVA calculation:

Σ light =1.818+2.727+2.045+2.045+2.727+0.682= 10 A.

Σ Power sockets= 0.5[(7.57×4)] =15.14 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[10+15.14] =19.66 A.

∴ 𝑲𝑽𝑨𝒈𝒓𝒐𝒖𝒏𝒅=19.66×220=4.325 KVA.

Then,


C.S.A =3×10 mm².

Riser calculation: We will have 26 building of this type, each of 2 apartments duplex.

we get the diversified KVA of apartment.

∴ 𝑲𝑽𝑨𝒂𝒑𝒂𝒓𝒕𝒎𝒆𝒏𝒕(𝒅𝒊𝒗𝒆𝒔𝒊𝒇𝒊𝒆𝒅) =0.7[14.377+13.7] =19.66 KVA.

∴ 𝑲𝑽𝑨𝒗𝒊𝒍𝒍𝒂=19.66×2+4.18=31.7 KVA.

∴ 𝑰𝑹𝒊𝒔𝒆𝒓 =31.7∗103

380 3 =48.16 A.


C.S.A =3×25+25+25 mm².



53

Fig 2.21 Distribution of Light in Villa type (A) ground floor.


54

Fig 2.22 Distribution of Sockets in Villa type (A) ground floor.


55

Fig 2.23 Distribution of lighting in Villa (A) First floor.


56

Fig 2.24 Distribution of Sockets in Villa (A) First floor.


57

Fig 2.25 Distribution board in Villa type (A) ground floor.

Fig 2.26 Distribution board in Villa type (A) First floor.

²

² ²

²

² ² ² ² ² ² ² ² ² ² ²

² ² ² ² ² ²

² ² ²

²

² ² ² ² ² ²²²²² ² ² ² ² ²


58

Fig 2.27 Distribution board in Villa type (A) Garage.

²

²

²

Fig 2.28 Riser diagram in Villa type (A).

² ²

² ² ²

² ²

²

² ² ²

2.7.7 Villa type (B)

Ground Floor:

a) Lighting:

line Room Lux Area u n no. of lamps

lamps lamps

wattage power factor installed wattage lamp current LINE 1 LINE2 LINE 3 LINE4 LINE5

L1 - - -

12 100

1200 5.45 5.45

L2,L3 Reception 150 85.9 0.49 20 16.4 16 100 1 1600 7.27

3.64 3.64

L2 Terrace 150 20.52 0.49 20 3.9

3 100 1 300 1.36

1.36

L3

0.49 20 4 40 1 160 0.72

0.7

L4 Bathroom1 300 7 0.35 80 2.2 2 40 0.8 80 0.45

0.45

L4 Bathroom2 300 8 0.35 80 2.2 2 40 0.8 80 0.45

0.45

L4 Store 100 4.2 0.49 80 0.66 1 20 0.8 20 0.114

0.114

L4 kitchen 300 21.2 0.41 80 6.05 6 40 0.8 240 1.36

1.36

L4 kitchen balcony 100 3 0.49 80 0.47 1 20 0.8 20 0.114

0.114

L4 Entrance 200 12 0.49 20 3.06 3 100 1 300 1.36

1.36

L4 door lights - -

3 15 1 45 0.2

0.2

L5 M.bedroom 150 32.5 0.49 20

6.2 6 100 1 600 2.72

2.72

0.49 20 4 40 1 160 0.72

0.72

SUM 5.45 5 4.34 4.05 3.44

C.B 6.54 6 5.2 4.85 4.128

closest C.B 10 10 10 10 10


60


Line Type Calculations current C.B. rating M.C.B C.S.A

L1 Lighting - 5.45 - 10 3*2.5mm²

L2 Lighting - 5 - 10 3*2.5mm²

L3 Lighting - 4.34 - 10 3*2.5mm²

L4 Lighting - 4.05 - 10 3*2.5mm²

L5 Lighting - 3.44 - 10 3*2.5mm²

L6 Normal socket 2+0.2(2*5) 4 4.8 10 3*2.5mm²


L8 power plug 1*10 10 12 16 3*4mm²

L9 power plug 1*10 10 12 16 3*4mm²

L10 power plug 1*10 10 12 16 3*4mm²

L11 power plug 1*10 10 12 16 3*4mm²

L12 power plug 1*10 10 12 16 3*4mm²

L13 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mm²

L14 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mm²

L15 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mm²

L16 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mm²

L17 IP55 1500/(220*0.9) 7.6 9.2 10 3*2.5mm²

L18 IP55 1500/(220*0.9) 7.6 9.2 10 3*2.5mm²

L19 Elevator 1.5*746/(220*0.9) 5.7 10 16 3*4mm²

c) KVA calculation:

Σ light =5.45+5+4.34+4.05+3.44= 22.28 A.

Σ Normal sockets= (4×2) =8 A.

Σ Power sockets= (11.4×4) + (7.6×2) +0.5[10×3] =75.8 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[22.28+8+75.8] =74.256 A.

∴ 𝑲𝑽𝑨𝒈𝒓𝒐𝒖𝒏𝒅=74.256×220=16.336 KVA.


3= 24.752 𝐴.

Then,


C.S.A =5×10 mm².

First Floor:

a) Lighting:

Room Lux Area u n no. of lamps lamps lamps wattage power factor installed wattage lamp current LINE 1 LINE2 LINE 3

L1 M.bedroom 150 36.2 0.49 20 6.7 6 100 1 600 2.72 2.72

L1 Terrace 150 32.2 0.49 20 6.1

4 100 1 400 1.8 1.8

L1

0.49 20 4 40 1 160 0.72 0.72

L2 Bedroom1 150 30 0.49 20 5.7

4 100 1 400 1.8

1.8

L2

0.49 20 4 40 1 160 0.72

0.72

L2 Bedroom2 150 20.5 0.49 20 3.9 4 100 1 400 1.8

1.8

L2 Bathroom1 300 7 0.35 80 2.2 2 40 0.8 80 0.36

0.45

L3 Living 150 20.8 0.49 20 3.9 4 100 1 400 1.8

1.8

L3 corridor 100 5 0.49 20 0.7 2 40 1 80 0.36

0.36

L3 stairs area 100 10 0.49 20 1.4 1 100 1 100 0.45

0.45

L3 kitchen 300 6.3 0.41 20 2.1 2 100 1 200 0.9

0.9

L3 kitchen bar

3 15 1 45 0.2

0.2

L3 Dressing 150 11 0.49 80 0.8 1 20 0.8 20 0.1

0.1

L3 Bathroom2 300 7 0.35 80 2.2 2 40 0.8 80 0.36

0.36

L3 corridor 100 5 0.49 20 0.7 2 40 1 80 0.36

0.36

SUM 5.24 4.68 4.53

C.B 6.3 5.6 5.436

closest C.B 10 10 10


62


Line Type Calculations current column C.B C.S.A

L1 Lighting - 5.24 - 10 3*2.5mm²

L2 Lighting - 4.68 - 10 3*2.5mm²

L3 Lighting - 4.53 - 10 3*2.5mm²

L4 Normal socket 2+0.2(2*6) 4.4 5.6 10 3*2.5mm²


L6 power plug 1*10 10 12 16 3*4mm²

L7 IP55 1500/(220*0.9) 7.6 9.2 10 3*2.5mm²

L8 IP55 1500/(220*0.9) 7.6 9.2 10 3*2.5mm²

L9 A/C 2.25*746/(220*0.9) 8.5 10.2 20 3*6mm²

L10 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mm²

L11 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mm²

L12 A/C 2.25*746/(220*0.9) 8.5 10.2 20 3*6mm²

L13 A/C 2.25*746/(220*0.9) 8.5 10.2 20 3*6mm²

c) KVA calculation:

Σ light =5.24+4.68+4.53= 14.42 A.

Σ Normal sockets= 4.4+4 =8.4 A.

Σ Power sockets=(11.4×2) + (7.6×2) + (8.5×3) + (10) =73.5 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[14.42+8.4+73.5] =67.424 A.

∴ 𝑲𝑽𝑨𝑭𝒊𝒓𝒔𝒕=67.424*220=15 KVA.


3= 22.47 𝐴.

Then,


C.S.A =5×10 mm².


63

Roof Floor:

a) Lighting: line Room Lux Area u n

no. of lamps

lamps

lamps wattage

power factor

installed wattage

lamp current

LINE 1 LINE2

L2 Bedroom 150 26.4 0.49 20 5.6

4 100 1 400 1.8

1.8

L2

0.49 20 4 40 1 160 0.72

0.72

L2 Bathroom 300 7.5 0.35 80 2.2 2 40 0.8 80 0.36

0.36

L2 kitchen 300 3.5 0.49 20 1.12 1 100 1 100 0.45

0.45

L2 kitchen

bar 3 15 1 45 0.19

0.19

L2 Living 150 22 0.49 20 4.73

3 100 1 300 1.6

1.6

L1

0.49 20 4 40 1 160 0.72 0.72

L2 corridor 100 10 0.49 20 0.6 2 40 1 80 0.36

0.36

L1 Roof - -

9 100 1 900 4.09 4.09

SUM 4.81 5.12

C.B 5.77 6.144

closest C.B 10 10


Line Type Calculations current C.B. rating M.C.B C.S.A

L1 Lighting - 4.81 - 10 3*2.5mm²

L2 Lighting - 5.12 - 10 3*2.5mm²

L3 Normal socket 2+0.2(2*4) 3.6 4.2 10 3*2.5mm²


L5 power plug 1*10 10 12 16 3*4mm²

L6 A/C 2.25*746/(220*0.9) 8.5 10.2 20 3*6mm²

L7 A/C 3*746/(220*0.9) 11.4 13.7 25 3*10mm²

L8 IP55 1500/(220*0.9) 7.6 9.2 10 3*2.5mm²

c) KVA calculation:

Σ light =4.81+5.12= 9.93 A.

Σ Normal sockets= 3.6+4 =7.6 A.

Σ Power sockets= 8.5+11.4+7.6+10 =37.5 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[9.93+7.6+13.75] =38.521 A.

∴ 𝑲𝑽𝑨𝑭𝒊𝒓𝒔𝒕=38.521*220=8.4746 KVA.


3= 12.84 𝐴.

Then,


C.S.A =5×6 mm².


64

d) Riser calculation:

We will have 96 building of this type; we get the diversified KVA of apartment.

∴ 𝑲𝑽𝑨𝒗𝒊𝒍𝒍𝒂 =0.6[8.5+15+16.5] =24 KVA.

∴ 𝑰𝑹𝒊𝒔𝒆𝒓 =24∗103

380 3 =36.46 A.


C.S.A =3×25+25+25 mm².



65

Fig 2.29 Distribution of lighting in Villa (B) Ground floor.


66

Fig 2.30 Distribution of Sockets in Villa (B) Ground floor.


67

Fig 2.31 Distribution of lighting in Villa (B) First floor.

Fig 2.32 Distribution of Sockets in Villa (B) First floor.

First Floor Plan

First Floor Plan


68

Fig 2.33 Distribution board in Villa type (B) ground floor.

Fig 2.34 Distribution board in Villa type (B) First.

²

² ²

²

² ² ² ² ² ² ² ² ² ² ²

² ² ² ²

²

² ² ² ² ² ² ² ² ² ² ²² ²


69

Fig 2.35 Distribution board in Villa type (B) Roof.

Fig 2.36 Riser diagram in Villa type (B).

² ²

²

² ²

²

²²²

²

²

²

2.7.8 Villa type (C)

Basement Floor:

a) Lighting:

lines place room calculated

number of lamps

installed number of

lamps length width Lux Area U m Ƞ

lamps wattage

number of lamps

installed wattage

power factor

lamp current

line 1

line 2

line 3

line 4

1 1 entrance 6 6 18.835 3.36 50 63.2856 0.6 0.8 20 60 5.493542 360 1 1.63636 1.636

1 2 cinema 10 4 7.42 4.75 75 35.245 0.5 0.8 20 40 8.260547 160 1 0.72727 0.727

1

6

40

240 1 1.09091 1.091

2 3 living 6 6 4.69 4.12 150 19.3228 0.5 0.8 20 60 6.038375 360 1 1.63636

1.636

1 4 balcony 1 1 2.637 0.95 50 2.50515 0.5 0.8 20 40 0.39143 40 1 0.18182 0.182

2 5 big bathroom 9 10 4.69 5.32 300 24.9508 0.35 0.8 80 40 8.354063 400 1 1.81818

1.818

2 6 small bathroom 1 1 2 1.475 300 2.95 0.35 0.6 80 40 1.316964 40 0.8 0.22727

0.227

2

1

25

25 0.8 0.14205

0.142

2

0.7

0.7

2 7 bathroom extension

1 1 1.5 2.5 150 3.75 0.5 0.6 80 40 0.585938 40 0.8 0.22727

0.227

2

1

25

25 0.8 0.14205

0.142

2,3 8 stairs 1 6 6 9.113 3.6 50 32.8068 0.5 0.8 20 40 5.126063 240 1 1.09091

0.366 0.733

3 9 mosque

extension 3 3 1.8 3.7 150 6.66 0.5 0.8 20 40 3.121875 120 1 0.54545

0.546

3 10 mosque 8 8 6 3.7 200 22.2 0.5 0.8 80 20 6.9375 160 0.8 0.90909

0.909

3 11 corridor 1 1 1.68 1.23 50 2.0664 0.5 0.8 80 20 0.161438 20 0.8 0.11364

0.114

4 12 kitchen 8 8 4.5 6.5 300 29.25 0.41 0.8 80 40 8.360328 320 0.8 1.81818

1.818

3 13 door man room

bathroom 1 1 1.7 1.6 300 2.72 0.35 0.8 80 40 0.910714 40 0.8 0.22727

0.227

3

1

25 0.8 0.14205

0.142

3

0.7

0.7

3 14 door man room 5 4 3 2.875 120 43.64 0.5 0.6 20 100 8.728 400 1 1.81818

1.818

3 14

1

40

40 0.8 0.22727

0.227

4 15 servant room 4 4 4.13 3.65 120 15.0745 0.5 0.8 20 60 3.768625 240 1 1.09091

1.091

4 16 servant room

entrance 1 1 1.231 1.788 75 2.201028 0.5 0.8 80 40 0.128966 40 0.8 0.22727

0.227

4 17 servant room

bathroom 1 1 1.46 1.705 300 2.4893 0.35 0.6 80 40 1.111295 40 0.8 0.22727

0.227

4

1

25

25 0.8 0.14205

0.142

4

0.7

0.7

1 18 villa entrance 12 12 11.7 2.28 200 20.825 0.5 0.8 20 40 13.01563 480 1 2.18182 2.182

4 19 stairs 2 6 6 11.21 0.878 50 48.46 0.6 0.8 20 40 6.309896 240 1 1.09091

1.091

sum 5.818 5.259 5.416 5.296

C.B 10 10 10 10


71


Line Type number calculations current Column1 C.B C.S.A

line1 Lighting - - 5.818 - 10 3*2.5 mm²

line2 Lighting - - 5.26 - 10 3*2.5 mm²

line3 Lighting - - 5.416 - 10 3*2.5 mm²

line4 Lighting - - 5.3 - 10 3*2.5 mm²

line5 normal sockets 5 2+.2(2X4) 3.6 4.32 10 3*4 mm²





line10 normal sockets 6 2+.2(2X5) 4 4.8 10 3*4 mm²


line12 power socket 1 1x16 16 19.2 20 3*6 mm²




line16 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mm²

line17 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mm²

line18 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mm²

line19 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mm²

line20 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mm²

line21 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mm²

line22 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mm²

c) KVA calculation: Σ light =5.818+5.26+5.416+5.3= 21.79 A.

Σ Normal sockets=4.4+4+ (3.6×5) =26.4 A.

Σ Power sockets=0.3[(8.477×4) + (7.57×3) + (16×4)] =33.64 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[21.79+26.4+33.64] =57.267 A.


3= 19.09 𝐴.

Then,


C.S.A =5×16 mm²

Phase balance:

Phase A Phase B Phase C

light Line number L1,L2 L3 L4

current 11.0772 5.416 5.2964

Normal sockets Line number L(5,6) L(7,8) L(9,10,11)

current 7.2 8 11.2

Power sockets Line number L(12,16,17,19) L(13,14,20) L(15,18,21,22)

current 39.617 40.477 40.524

Sum

57.8942 53.893 57.0204

Ground Floor:

a) Lighting:

place room calculated number of

lamps

installed number of

lamps length width Lux Area U m Ƞ

lamps wattage

number of lamps

installed wattage

power factor

lamp current

LINE1 LINE2 LINE3

1 saloon 1 11 12 4.5 8.928 150 40.176 0.6 0.8 20 60 10.4625 720 1 3.272727 3.2727

2 reception 7 6 4.5 3.34 150 15.03 0.5 0.6 20 60 6.2625 360 1 1.636364 1.6363

3 saloon2 7 6 4.25 4.8 150 20.4 0.5 0.8 20 60 6.375 360 1 1.636364

1.6363

4 dining room

13 12 4.6 6.5 200 29.9 0.5 0.8 20 60 12.45833 720 1 3.272727

3.273

5 blank 6 6 4.5 4 150 18 0.5 0.8 20 60 5.625 360 1 1.636364

1.636

6 stairs 4 4 3.6 9 50 32.4 0.5 0.8 20 60 3.375 240 1 1.090909

1.09

7 passage 1 1 1 2 50 2 0.5 0.8 80 40 0.078125 40 0.8 0.227273

0.2273

8 bath ext. 1 1 1.72 1.85 150 3.182 0.5 0.8 80 40 0.372891 40 0.8 0.227273

0.2273

9 bath room 1 1 1.85 1.28 300 2.368 0.35 0.6 80 40 1.057143 40 0.8 0.227273

0.2273

1

0.35 0.6 80 25

25 0.8 0.142045

0.142

0.7

0.7

10 entrance 3 4 4 3.325 100 13.3 0.5 0.8 20 60 2.770833 240 1 1.090909

1.09

11 kitchen 5 6 4.5 4.16 300 18.72 0.5 0.8 80 40 4.3875 240 0.8 1.363636

1.363

12 back stairs 1 1 1.1 0.95 50 1.045 0.5 0.8 20 40 0.163281 40 1 0.181818

0.1818

13 balcony 5 6 11.5 2.3 50 26.45 0.5 0.8 20 40 4.132813 240 1 1.090909 1.09

SUM 5.999 5.795 5.999

C.B 10 10 10


73


Line Type number calculations current Column1 C.B C.S.A

line1 Lighting - - 5.99 - 10 3*2.5 mm²

line2 Lighting - - 5.79 - 10 3*2.5 mm²

line3 Lighting - - 5.99 - 10 3*2.5 mm²



line6 normal sockets 5 2+.2(4x2) 3.6 4.32 10 3*4 mm²







line13 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mm²

line14 AC 1 2.25x7456/(220x0.9) 8.477 10.1724 25 3*6 mm²

line15 AC 1 2.25x7456/(220x0.9) 8.477 10.1724 25 3*6 mm²

line16 AC 1 2.25x7456/(220x0.9) 8.477 10.1724 25 3*6 mm²

line17 AC 1 2.25x7456/(220x0.9) 8.477 10.1724 25 3*6 mm²

c) KVA calculation: Σ light =5.99+5.79+5.99= 17.77 A.

Σ Normal sockets=4.4+ (4×3) + (3.6×2) =23.6 A.

Σ Power sockets=0.5[(8.477×4) + (7.57) + (16×3)] =44.739 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[17.77+23.6+44.739] =60.276 A.


3= 20.092 𝐴.

Then,


C.S.A =5×16 mm²

Phase balance:


light Line number L1 _ L2,L3

current 5.99

11.78

Normal sockets Line number L(4,5) L(6,7) L(8,9)

current 8 8 7.6

Power sockets Line number L(10,14,15) L(11,16,17) L(12,13)

current 32.954 32.954 23.57

Sum

46.944 40.954 42.95

First Floor:

a) Lighting:

LINES place room calculated number of

lamps

installed number of lamps

length width Lux Area U m Ƞ lamps

wattage number of lamps

installed wattage

power factor

lamp current

line1 line2 line3 line4

1 1 main bed room 5 6 4.5 4.35 120 19.575 0.5 0.8 20 60 4.89375 360 1 1.636364 1.6363

1 2 balcony 0 1 1 2.36 0.5 50 1.18 0.5 0.6 20 40 0.245833 40 1 0.181818 0.1818

1 3 bed room living 7 6 3.9 4 150 15.6 0.5 0.6 20 60 6.5 360 1 1.636364 1.6363

1 4 balcony 1 1 1 4 1 50 4 0.5 0.8 20 40 0.625 40 1 0.181818 0.1818

1 5 bed room 1 5 6 4.5 4.4 120 19.8 0.5 0.8 20 60 4.95 360 1 1.636364 1.6363

1 6 balcony 2 1 1 2.36 0.5 50 1.18 0.5 0.8 20 40 0.184375 40 1 0.181818 0.1818

2 7 closet 1 2 2 2 3.12 250 6.24 0.5 0.8 80 40 1.21875 80 1 0.363636

0.3636

2 8 corridor1 1 1 1.26 5.643 50 7.11018 0.5 0.8 80 40 0.277741 40 0.8 0.227273

0.2273

2 9 bath room 1 4 4 3.52 3.12 300 10.9824 0.35 0.8 80 40 3.677143 160 0.8 0.909091

0.909

2

1

0.35 0.8 80 25

25 0.8 0.142045

0.142

2

0.7

0.7

2 10 closet 2 2 2 4.26 2 250 8.52 0.5 0.8 80 40 1.664063 80 0.8 0.454545

0.454

2 11 bathroom 2 3 3 3.18 2 300 6.36 0.35 0.8 80 40 2.129464 120 0.8 0.681818

0.6818

2

1

0.35 0.8 80 25

25 0.8 0.142045

0.142

2

0.7

0.7

2 12 corridor 2 1 1 1.2 2 50 2.4 0.5 0.8 80 40 0.09375 40 0.8 0.227273

0.2273

3,4 13 hall 9 8 4.6 9 100 41.4 0.5 0.8 20 60 8.625 480 1 2.181818

1.09 1.09

3 14 bed room 2 6 6 4.5 4.5 120 20.25 0.5 0.8 20 60 5.0625 360 1 1.636364

1.6363

3 15 balcony 3 1 1 2.36 0.5 50 1.18 0.5 0.8 20 40 0.184375 40 1 0.181818

0.1818

3 16 corridor 1 1 1.332 1.87 50 2.49084 0.5 0.8 80 40 0.097298 40 0.8 0.227273

0.2273

4 18 corridor 1 1 1.2652 2.01 50 2.543052 0.5 0.8 80 40 0.099338 40 0.8 0.227273

0.2273

4 19 bathroom 3 3 3 3.12 2.01 300 6.2712 0.35 0.8 80 40 2.099732 120 0.8 0.681818

0.6818

4

1

0.35 0.8 80 25

25 0.8 0.142045

0.142

4

0.7

0.7

4 21 bed room 3 6 6 4.578 4.63 120 21.19614 0.5 0.8 20 60 5.299035 360 1 1.636364

1.6363

4 22 balcony 3 1 1 2.36 0.5 50 1.18 0.5 0.8 20 40 0.184375 40 1 0.181818

0.1818

3 23 bathroom 4 3 3 3.12 2.01 300 6.2712 0.35 0.8 80 40 2.099732 120 0.8 0.681818

0.6818

3

1

0.35 0.8 80 25

25 0.8 0.142045

0.142

3

0.7

0.7

sum 5.4543 4.547 4.6592 4.6592

C.B 10 10 10 10


75


Lines Type number calculations current Column1 C.B C.S.A

line1 Lighting - - 5.454 - 10 3*2.5 mm²

line2 Lighting - - 4.547 - 10 3*2.5 mm²

line3 Lighting - - 4.66 - 10 3*2.5 mm²

line4 Lighting - - 4.66 - 10 3*2.5 mm²








line12 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mm²

line13 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mm²

line14 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mm²

line15 WH 1 (1500/220x.9) 7.57 9.084 16 3*4 mm²

line16 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mm²

line17 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mm²

line18 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mm²

line19 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mm²

line20 AC 1 2.25x746/(220x0.9) 8.477 10.1724 25 3*6 mm²

d) KVA calculation: Σ light =5.454+4.547+4.66+4.66= 19.27 A.

Σ Normal sockets= (4.4×4) + 4 + (3.6×2) =28.8 A.

Σ Power sockets=0.5[(8.477×5) + (7.57×4)] =32.094 A.

∴ 𝑰𝒎𝒂𝒊𝒏=0.7[19.27+28.8+32.094] =56.1148 A.


3= 18.705 𝐴.

Then,


C.S.A =5×16 mm²

Phase balance:


light Line number L1,L2 L3 L4

current 10.001 4.66 4.66

Normal sockets Line number L(5,6,7) L(8) L(9,10,11)

current 12.8 3.6 12.4

Power sockets Line number L(12,16) L(13,14,17,18) L(15,19,20)

current 16.047 32.094 24.524

Sum

38.848 40.354 41.584


76

Riser calculation:

We will have 23 building of this type; we get the diversified KVA of Villa. =0.7[57.267+60.276+56.1148] =121.56 A. =121.56×220=26.74 KVA.

= 26 .74103

380 √3 =40.627 A.

Then,

Fuse=63 A (3 phase). C.S.A =3×35+35+35 mm². Meter used = 80A Three phase meter.

Fig 2.37 Distribution of lighting in Villa (C) Basement floor.


77

Fig 2.38 Distribution of Sockets in Villa (C) Basement floor.


78

Fig2.39 Distribution of Light in Villa (C) Ground floor.


79

Fig 2.40 Distribution of Sockets in Villa (C) Ground floor


80

Fig 2.41 Distribution of Light in Villa (C) First floor


81

Fig 2.42 Distribution of Sockets in Villa (C) First floor


82

Fig 2.43 Distribution board in Villa type (C) Basement.

Fig 2.44 Distribution board in Villa type (C) Ground Floor.

² ²

²

² ² ² ² ² ² ² ² ² ² ² ² ² ² ² ²

²² ² ²

²

²² ² ² ² ² ² ²²²²²²²

²

² ²


83

Fig 2.45 Distribution board in Villa type (C) First floor.

Fig 2.46 Riser diagram in Villa type (C)

²

²² ² ² ² ² ² ² ² ² ² ² ² ² ² ²

²

² ² ²

Basement

²

²

²

LOW VOLATGE DISTUBUTION NETWORK

PLANNING

Chapter 3

CHAPTER 3 LOW VOLTAGE DISTRIBUTION NETWORK PLANNING

84

Chapter 3

LOW VOLATGE DISTUBUTION NETWORK PLANNING

3.1 Introduction

In designing a system, distribution engineers may find a conflict between fulfilling

the requirements of the electrical considerations and the economical considerations in

the same time, so the good distribution system is the one than can fulfill both

considerations as much as possible in the same time.

An example of this conflict is the voltage drop on the feeders. For achieving good

performance of the system, voltage drop should be eliminated in order to have a flat

voltage profile. To achieve this we use cables of larger cross sectional area (c.s.a) in

order to have smaller resistance. On the other hand, the economical considerations in

some cases permits a certain range of voltage drop so as to fully use the used cables.

Yet if the conflict between electrical requirements and economical requirements can't

be solved; the priority is always for the electrical requirements since they represent

the safe operation which is the main aim of the distribution engineer.

Another example on the conflict between electrical and economical requirements

is to increase the service reliability for the critical loads, e.g. hospitals, computer and

control centers, critical industrial loads. To do this some back-up systems such as

emergency generators and/or batteries with automatic switching devices are used in

such places. These extra equipments cost more money, yet the reliability of the

service is more important than money in this case.

In their system design decisions of the secondary distribution network,

distribution engineers are primarily motivated by the considerations of economy,

coppers losses in the transformer and the secondary circuit, permissible voltage drops

and voltage flickers of the system. Of course, there are some other engineering and

economic factors affecting the selection of the distribution transformer and the

secondary configuration, such as permissible transformer loading, balanced phase

loads for the primary system, investment costs of the various secondary system

components, cost of labor, capital cost, inflation rates and other factors.

3.2 General Overview on the distribution system

The main components of the low voltage distribution network (secondary

distribution network):

3.2.1 Distribution Transformer

The first step of the low voltage distribution network is the distribution

transformer. At normal operation the transformer is loaded with 80% of its full load to

be able to withstand the loads of other transformer in case of fault. Distribution

transformers are put in either a kiosk in the street or in a room that is specially

designed for it. The transformer room is generally made of two compartments; the

RMU is placed in one of them and the transformer itself is placed in the other room.

This is to avoid any problems that might happen in the transformer when the switches

of the RMU are closed or opened. At normal operation the feeders are loaded with

70% of their full load to be able to withstand the other loads in case of fault; these

feeders are aluminum, because the probability of stealing copper cables is high.


85

3.2.2 Distribution Box (Pillar)

The second step in the network is the distribution box (pillar). The pillar can be

seen on the street. It’s a short metal box. It is used to connect the distribution

transformer to the building box. The pillar is fed from two different feeders; one

comes from a distribution transformer and the other comes from another feeder on the

same transformer or another distribution transformer. When the pillar is fed from two

feeders from the same transformer and a fault occurs on this transformer; this

transformer goes out the network so this pillar will go out of the network too, but this

method is cheap and the maneuvering on network will be easy. On the other hand if

the pillar is fed from two feeders and each one comes from a different transformer, the

pillar has a supply in case a fault occurs on one of the two transformers, but this

method is expensive and the maneuvering on network will be more complicated. At

normal operation the pillar is loaded with 80% of its full load to be able to withstand

the loads of other pillar in case of fault. At normal operation the feeders are loaded

with 70% of their full load to be able to withstand the other loads in case of fault.

These feeders are aluminum, because the probability of stealing copper cables is high.

The pillar connection is shown in figure 3.1.

To Building Boxes

From Distribution Transformer

In Out

High Rupture

Fuse

Fig 3.1 Distribution box (Pillar)

In all these methods the pillar is connected to other pillars, and each feeder feeds a

group of pillars, there is a switch in mid way of two feeder to isolate the feeders from

each other and to balance the loading, but in case a fault occurs the faulty part is

isolated and the midway switch is closed to connect the healthy feeder to the loads on

the faulty feeder. These methods used to make sure that the continuity of supply is

achieved. This is shown in figure 3.2.

Piller Piller Piller

Piller Piller Piller

Fig 3.2 Feeding a group of pillars


86

3.2.3 Building Box (Coffree)

The third step on the network and the last one before the risers of houses is the

building box (sometimes called coffree). It used to connect pillars to risers of houses.

The coffree is fed from two different feeders; one comes from a pillar and the other

comes from another pillar, the coffree has a supply in case a fault occurs in one of the

two pillars, and the department of electricity can make maneuvering on network to

achieve the continuity of supply. This is shown in figure 3.3.

Coffree Coffree Coffree

Coffree Coffree Coffree

Piller

Piller

Fig 3.3 Feeding a Group of coffrees

The coffree is connected to the network by two feeders one goes in and the other

goes out. The fuse set is connected on the riser may be three single phase fuses to

prevent the failure in supply in case of the fuse of one phase is burnt , or one three

phase fuse if one phase suffer from over current the three phase supply will

disconnect. Riser is made of copper, because it has high conductivity, and it is safe

from stealing. The riser is shown in figure 3.4.

In Out

Riser

Fig 3.4 The Riser


87

3.3 Low Voltage Network (LVN) types

The part of the electric utility system which is between the distribution

transformers and the consumer's property (i.e. the circuit between the distribution

transformers and the pillars, and the circuit between the pillars and the consumer's

property) is called the Low Voltage Network (LVN). The types of LVN include:

1) Radial System

2) Open Loop (Ring) System

3.3.1 Radial LVN

For simplicity in both installation and operation, the radial system is the most

suitable one, and has low cost as well. A representative schematic diagram of such

LVN type is shown in figure 3.5.

Fig 3.5 Single line diagram of LVN

3.3.2 Open Loop (Ring) LVN

To obtain higher reliability of the network, open loop (ring) type system is chosen.

In such system any area has a main feeding system and an alternative on in case of

emergency. This is the method used in this project. This is shown in figure 3.6.

LV Side of

distribution

transformer

Transformer (1) Transformer (2)

n.o.

n.o.

n.o.

Piller

Buildings

Fig 3.6 Single line diagram of open loop LVN (two supply points)


88

We can notice that an open loop LVN can also be applied to a single supply

system as shown in figure 3.7. Yet this technique is not recommended because if a

fault occurs on the transformer; then all pillars connected to it will fail to deliver

power to their loads.

LV Side of

distribution

transformer

Transformer

n.o.

n.o.

Piller

Buildings

n.o.

Fig. 3.7 Single line diagram of open loop LVN (one-supply point)

3.4 General points to be considered in design

1. It is always preferred to put the distribution transformers in gardens as

possible; yet the environmental constraints should be also fulfilled.

2. For buildings of flats we usually use the diversification chart since the load

profile between buildings is not necessary to be the same so we can't take a

certain figure to be the diversity factor.

3. Diversification is used for any node that supplies more than one node; i.e. if

the pillar feeds more than one feeder then to get the load of the pillar we

consider diversification between these feeders. Same is done when considering

distribution transformers and pillars.

4. The locations of the transformers and pillars and the routes of the cables are

chosen so that:

The maximum voltage drop between any transformer and the furthest

consumer is 5% of the nominal voltage (220 V). to overcome this

voltage drop taps on the high tension side of the distribution

transformers are adjusted so that the consumer receives 220 V

The crossing between cables should be avoided as much as possible.

The routes of the cables should avoid street crossing as much as

possible so that when maintenance in feeders is done we don't need to

dig across the streets to get the cables out.

5. As we mentioned before the distribution boxes are connected in loops and so

does the coffree of the buildings. Thus if two coffrees or two boxes of

different loads are connected together then it is recommended that both have

the same c.s.a of feeders which suits the one with the larger load. This is very

important so that if a fault occurs on the box with larger load; the feeder of the

other box can withstand the overload safely.


89

6. Low voltage fuses ratings are as follows: 2, 4, 6, 8, 10, 16, 20, 25, 32, 35, 40,

50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1000 and1250

Amperes according to ABB pocket book (switchgear manual), 8th edition.

7. Standard ratings of pillars are 50,100 KVA,150 KVA, and 200 KVA

8. Standard ratings of distribution transformers are 500 KVA and 1000 KVA.

9. Standard rating of street lighting pillars is 100A =22KVA

10. Additional 25% spare equipments should be used in the design; i.e. if the

design shows the need of 4 cables then a fifth cable is added as a spare. In this

project the extra equipments are not shown in the drawings but it is understood

that they are found.

11. In the secondary distribution networks the c.s.a of the cables used shouldn't be

less than (3×70 + 35) mm² or else the voltage drop will be severe and may be

more than the permissible ranges.

3.5 Planning of Distribution Network in the Residential Area:

A residential area for population of 35,291persons is divided into eight parts.

According to the population percentage occupying each type; our task is to:

1. Arrange their houses and service centers.

2. Arrange their supplying boxes so as to increase the reliability of the supply

and also its continuity.

3. Connect the boxes to their distribution transformers.

Calculations in this part depend on trial and error concept, and there are many

solutions. One of them is acceptable and the others are refused.

3.5.1 Calculation of Distribution Boxes (Pillars) and Feeders ratings:

For all the areas:

3.5.1.a Pillars:

I) Select the number of buildings to be fed by one pillar.

II) Calculate the number of flats per pillar.

III) Calculate the diversified KVA using the diversification chart.

IV) Pillar Loading = Diversified KVA × Number of flats per pillar.

V) Select Pillar rating.

VI) Calculate number of pillars = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑏𝑢𝑖𝑙𝑑𝑖𝑛𝑔𝑠

𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑝𝑖𝑙𝑙𝑎𝑟 𝑝𝑒𝑟 𝑏𝑢𝑖𝑙𝑑𝑖𝑛𝑔𝑠

3.5.1.b Feeders (Pillar – coffree)rating :

I) The feeder current Pillar Loading (KVA )×103

3×380×number of buildings per pillar=

II) Maximum feeder current = Feeder current

0.8

III) Enter tables of " Electro cable Egypt co. "

IV) Get the C.S.A for the feeder.

600/1000 volts -XLPE insulated multi cores cables with aluminum conductor

armored (SWA).

Pillar Calculations

Type Color Number

of Blocks KVA (Unit)

Buildings per Pillar

No. of flats per

pillar

Diversified KVA (Unit)

loading pillar

Pillar Rating (KVA)

C.S.A of feeder cables

mm²

No. of pillars

Building A Green 24 15.9 2 24 7.2 172.8 200 3×185+95 12

Building B Cyan 101 5 4 96 1.5 144 150 3×120+70 26

Building C Pink 145 7.26 4 96 2 192 200 3×185+95 37

Building D Orange 57 17.4 2 24 7.5 180 200 3×185+95 28

Building E Yellow

70 8.5 8 80 1.6 128 150 3×120+70 9

46 8.5 8 80 1.6 128 150 3×120+70 6

Villa A Red 26 31.7 6 --- 19 114 150 3×120+70 5

Villa B Blue 96 24 4 --- 16 64 100 3×120+70 24

Villa C White 23 26.74 6 --- 15 90 100 3×120+70 4


91

Pillar Fuse rating:

3.5.2 Calculation of Transformer and feeders ratings:

For all areas:

3.5.2.a Transformers :

I) Select the number of Pillars to be fed by one Transformer.

II) Calculate the number of flats per Transformer.

III) Calculate the diversified KVA using the diversification chart.

IV) Transformer Loading=(Diversified KVA× Number of flats per Transformer).

V) Select Transformer rating.

VI) Calculate number of Transformers = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑃𝑖𝑙𝑙𝑎𝑟𝑠

𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑝𝑖𝑙𝑙𝑎𝑟 𝑝𝑒𝑟 𝑇𝑟𝑎𝑛𝑠 .

3.5.2.b Feeders (Transformer – Pillar ) :

I) The feeder current =Transformer loading (KVA )×103

3×380×number of Pillars per Trans ..

II) Maximum feeder current =Feeder current

0.8, & taking into consideration the tie

line (open loop) between pillars for more reliable system.

III) Enter tables of "Electro cable Egypt co."

IV) Get the C.S.A for the feeder.


armored (SWA).

Type Color Incoming Feeder

Fuse (A) Outgoing Feeder

Fuse (A)

Building A Green 400/630 160/250

Building B Cyan 400/630 160/250

Building C Pink 400/630 250/400

Building D Orange 400/630 160/250

Building E Yellow 250/400 100/160

160/250

Villa A Red 250/400 160/250

Villa B Blue 160/250 80/100

Villa C White 160/250 100/160

Transformer Calculations

Type Color Number of Buildings

KVA (Unit)

Flats per

building

Buildings per Pillar

pillars per

transf.

KVA diversified

(Unit) transf.

loading transf.

C.S.A of cables mm²

No. of transf.

Transformer rating

Building A Green 24 15.9 12 2 3 5 360 2(3×185+95) 4 500

Building B Cyan 101 5 24 4 6 1.5 864 2(3×120+95) 5 1000

Building C Pink 145 7.26 24 4 4 2 768 2(3×185+95) 10 1000

Building D Orange 57 17.4 12 2 6 5.2 748.8 2(3×185+95) 5 1000

Building E Yellow

70 8.5 10 8 3 1.6 384 2(3×120+95) 3 500

46 8.5 10 8 3 1.6 384 2(3×120+95) 2 500

Villa A Red 26 31.7 ___ 6 5 13.5 405 2(3×120+95) 1 500

Villa B Blue 96 24 ___ 4 8 12 384 3×240+120 3 500

Villa C White 23 26.74 ___ 6 4 13 312 3×240+120 1 500


93

3.5.3 Voltage drop Calculations :

For all areas:

3.5.3.a Between pillar and farthest coffree :

I) Calculate the feeder current =𝑃𝑖𝑙𝑙𝑎𝑟 𝐿𝑜𝑎𝑑𝑖𝑛𝑔 (𝐾𝑉𝐴)×103

3×380×𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑓𝑒𝑒𝑑𝑒𝑟𝑠.

II) Measure longest distance between any pillar and coffree.


IV) Get the Voltage drop for the used C.S.A, (V/A/KM).

V) % V.D = 𝐹𝑒𝑒𝑑𝑒𝑟 𝑐𝑢𝑟𝑟𝑒𝑛𝑡 ×𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 ×𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑒𝑑 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑑𝑟𝑜𝑝

220× 100.

3.5.3.b Between Transformer and farthest Pillar :

I) The feeder current =Transformer loading (𝐾𝑉𝐴)×103

3×380×𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 Pillars 𝑝𝑒𝑟 Trans .×No .of circuits.

II) Measure longest distance between any Transformer and Pillar.


IV) Get the Voltage drop for the used C.S.A, (V/A/KM).

V) % V.D = 𝐹𝑒𝑒𝑑𝑒𝑟 𝑐𝑢𝑟𝑟𝑒𝑛𝑡 ×𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒 ×𝑠𝑝𝑒𝑐𝑖𝑓𝑖𝑒𝑑 𝑣𝑜𝑙𝑡𝑎𝑔𝑒 𝑑𝑟𝑜𝑝

220× 100

∴ Combined voltage drop = %V.D (Pillar-Coffree) +%V.D (Transformer-Pillar).

Transformer To Pillar Voltage Drop:

Type Color Length Pillar Diversified

(KVA) C.S.A of cables mm² VD (V/A/KM) Transf.-Pillar (%VD)

Building A Green 62.88 120 2(3×185+95) 0.424 1.104746757

Building B Cyan 120.88 144 2(3×120+95) 0.604 3.630420924

Building C Pink 110.86 192 2(3×185+95) 0.424 3.116341614

Building D Orange 117.4 124.8 2(3×185+95) 0.424 2.145120229

Building E Yellow

150 128 2(3×120+95) 0.604 4.004435169

140 128 2(3×120+95) 0.604 3.737472824

Villa A Red 223.46 81 2(3×120+95) 0.604 3.77506863

Villa B Blue 143.16 48 3×240+120 0.344 1.632504792

Villa C White 114.01 78 3×240+120 0.344 2.112657453

Pillar To coffree Voltage Drop

Type Color Length Coffree

Diversified(KVA)

C.S.A of cables mm² VD (V/A/KM) Pillar-Coffree (%VD) Combined (%VD)

Building A Green 62.88 86.4 3×185+95 0.424 1.59083533 2.695582086

Building B Cyan 29.54 36 3×120+70 0.604 0.443591306 4.07401223

Building C Pink 36.6 48 3×185+95 0.424 0.514424062 3.630765676

Building D Orange 4 90 3×185+95 0.424 0.105414767 2.250534996

Building E Yellow

50 16 3×120+70 0.604 0.333702931 4.338138099

55 16 3×120+70 0.604 0.367073224 4.104546048

Villa A Red 58.96 19 3×120+70 0.604 0.467284214 4.242352844

Villa B Blue 35 16 3×120+70 0.604 0.233592051 1.866096844

Villa C White 98.03 15 3×120+70 0.604 0.613366843 2.726024296


96

3.5.4 Short Circuit Current Calculations :

a) Calculate the impedance between (Pillar – coffree):

i. Measure the shortest distance between any Pillar-Coffree.

ii. Get from the tables the C/C's Impedance for the used cables (mΩ/meter).

iii. Impedance = measured distance × C/C's Impedance.

b) Calculate the impedance between (Pillar – Transformer):

i. Measure the shortest distance between any Transformer-Pillar.

ii. Get from the tables the C/C's Impedance for the used cables (mΩ/meter).

iii. Impedance = measured distance × C/C's Impedance

c) Calculate Transformer Impedance =4102

𝑇𝑟𝑎𝑛𝑠𝑓𝑜𝑟𝑚𝑒𝑟 𝑟𝑎𝑡𝑖𝑛𝑔× 6%

d) High Voltage network impedance = 0.319 mΩ

e) MLVSB Short Circuit Current (KA) =410

3× ImpedanceTransformerH .V netwok

f) Pillar Short Circuit current (KA) = 410

3× ImpedancePillarH .V netwok

g) Coffree S.C current (KA)= 410

3× ImpedanceCoffreeH .V netwok

Pillar to Coffree Impedance

Type Area(color) Shortest distance between coffree &

pillar(m) C.S.A of cables mm²

C/C'S Impedance (mΩ/meter)

Pillar to Coffree Impedance(mΩ)

Building A Green 20 3×185+95 0.212 4.24

Building B Cyan 11.74 3×120+70 0.325 3.8155

Building C Pink 13.48 3×185+95 0.212 2.85776

Building D Orange 21 3×185+95 0.212 4.452

Building E Yellow 12.34 3×120+70 0.325 4.0105

Villa A Red 17 3×120+70 0.325 5.525

Villa B Blue 10.2 3×120+70 0.325 3.315

Villa C White 16 3×120+70 0.325 5.2


98

Pillar to Transformer Impedance

Type Area(color) Shortest distance between

transformer& pillar(m) C.S.A of cables

mm² C/C'S Impedance

(mΩ/meter) Pillar to Transformer

Impedance(mΩ)

Building A Green 10 2(3×185+95) 0.212 1.06

Building B Cyan 17.74 2(3×120+95) 0.325 2.88275

Building C Pink 10 2(3×185+95) 0.212 1.06

Building D Orange 10.2 2(3×185+95) 0.212 1.0812

Building E Yellow 8.33 2(3×120+95) 0.325 1.353625

Villa A Red 80.5 2(3×120+95) 0.325 13.08125

Villa B Blue 28.22 3×240+120 0.163 4.59986

Villa C White 28.3 3×240+120 0.163 4.6129

Transformer and H.V network impedance

Type Area(color) Transformer rating(KVA) Transformer Impedance(mΩ) H.V network Impedance (mΩ)

Building A Green 500 20.172 0.319

Building B Cyan 1000 10.086 0.319

Building C Pink 1000 10.086 0.319

Building D Orange 1000 10.086 0.319

Building E Yellow 500 20.172 0.319

Villa A Red 500 20.172 0.319

Villa B Blue 500 20.172 0.319

Villa C White 500 20.172 0.319

Short Circuit Currents

Type Area(color) MLVSB Short Circuit current

(KA) Pillar Short Circuit current

(KA) Coffree Short Circuit current

(KA)

Building A Green 11.552077 10.983881 9.17814782

Building B Cyan 22.7499866 17.814424 13.8402707

Building C Pink 22.7499866 20.64663 16.5270947

Building D Orange 22.7499866 20.608522 14.8519664

Building E Yellow 11.552077 10.836241 9.15538449

Villa A Red 11.552077 7.0508712 6.05448236

Villa B Blue 11.552077 9.4342566 8.33326681

Villa C White 11.552077 9.429356 7.81132496


101

3.6 EXAMPLE OF CALCULATIONS:

For Building B (Cyan Area):

3.6.1 Calculation of Distribution Boxes (Pillars) and Feeders ratings:

3.6.1.a Pillars :

1. Number of buildings to be fed the pillar = 4 buildings.

2. Number of flats per pillar = 96 flats.

3. The diversified KVA of flat using the diversification chart = 1.5 KVA.

4. Pillar Loading = 1.5 x 96 = 144 KVA.

5. Pillar rating = 150 KVA.

6. Number of pillars = 101

4 = 26 pillar.

3.6.1.b Feeders (Pillar – coffree)rating :

1. The feeder current =144×103

3×380×4=54.69 A.

2. Maximum feeder current = 54.69

0.8=68.304 A.

3. Entering tables of "Electro cable Egypt co."

4. The C.S.A for the feeder = 3×120+70𝑚𝑚2.


armored (SWA).

3.6.2 Calculation of Transformer and feeders ratings:

3.6.2.a Transformers :

1. Number of Pillars to be fed by the Transformer =6 Pillars.

2. Number of flats per Transformer = 4×6×24=576 flats.

3. Diversified KVA using the diversification chart =1.5 KVA.

4. Transformer Loading=864 KVA.

5. Transformer rating = 1000 KVA.

6. Calculate number of Transformers = 26

6 = 5 transformers.

3.6.2.b Feeders (Transformer – Pillar) :

1. The feeder current 864×103

3×380×6==218.7 A

2. Maximum feeder current = 218.7

0.8=273.48 A

3. Entering tables of " Electro cable Egypt co. "

4. The C.S.A for the feeder = 2(3×120+95) 𝑚𝑚2


armored (SWA).


102

3.6.3 Voltage drop Calculations:

3.6.3.a Between pillar and farthest coffree :


3×380×4=54.69 A

2. longest distance between any pillar and coffree = 29.54 meter

3. Entering tables of " Electro cable Egypt co. "

4. The Voltage drop for the used C.S.A, (V/A/KM) = 0.604

5. % V.D = 54.69×29.54×0.604

220×1000× 100= 0.4435 %

3.6.3.b Between Transformer and farthest Pillar :


3×380×6×2=109.35 A

2. longest distance between any Transformer and Pillar =120.88 m

3. Enter tables of " Electro cable Egypt co. "

4. Get the Voltage drop for the used C.S.A, (V/A/KM).

5. % V.D = 109.35 ×120.88×0.604

220×1000× 100= 3.629 %

∴ Combined voltage drop = %V.D (Pillar-Coffree) +%V.D (Transformer-Pillar) = 4.0725 %

3.6.4 Short Circuit Current Calculations :

1. The impedance between (Pillar – coffree)

a. The shortest distance between Pillar-Coffree=11.74m

b. The C/C's Impedance for the used cable=0.325(mΩ/meter).

c. Impedance = 11.74 × 0.325=3.8155 mΩ.

2. The impedance between (Pillar – Transformer)

a. The shortest distance between Transformer-Pillar=17.74 m.

b. Get from the tables the C/C's Impedance for the used

cables=0.325/2 (mΩ/meter).

c. Impedance = 17.74x0.1625=2.88275 mΩ.

3. Calculate Transformer Impedance =4102

1000× 6%=10.086 mΩ.

4. High Voltage network impedance = 0.319 mΩ.

5. MLVSB Short Circuit Current (KA) =410

3×(0.319+10.086)=22.75 KA.

6. Pillar Short Circuit current (KA) = 410

3× 0.319+10.086+2.88 = 17.814 KA.

7. Coffree S.C current (KA) = 410

3×(0.319+10.086+2.88+3.8155)= 13.84 KA.

MEDIUM VOLTAGE DISTRIBUTION

NETWORK

Chapter 4

CHAPTER 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK

103

Chapter 4 MEDIUM VOLTAGE DISTRIBUTION NETWORK

4.1 Introduction In the previous chapter, we studied the way to design the low voltage network

(secondary distribution network) in the power system, which begins with the

distribution transformers and ends with the center of loads.

In this chapter, we’ll study the different ways to connect the medium voltage

network, which can also be named as primary distribution network which begins with

the high voltage distribution substations (for example 66/22 KV substation) which

step down the high voltage to a medium voltage which feeds the primary distribution

feeders.

4.2 General Overview on Medium Voltage Network (Primary

Distribution Network) We’ll begin our talk by a quick overview on the main components of the medium

voltage network (primary distribution network).

4.2.1 Substation

The medium voltage network begins with the substations; each substation contains

transformers that step down the high voltage coming from the generating source

through transmission lines to medium voltage coming out from these substations by

means of underground cables.

There are many ratings of stepping down substations, there are 66/11 KV

substations, 66/22 KV substations, and also there are substations of higher ratings that

began to appear in Egypt like the ones of rating 220/66/11 KV substations, and these

ones steps down the high voltage from 220 KV to 66 KV and steps from this high

voltage to a medium voltage of 11 KV.

Here in Egypt, the medium voltage is mainly 11 KV, but lately new networks of

22 KV are being installed for their better operation and the more advantages they

have.

The electric power is taken from these substations and delivered to medium

voltage distributors then to distribution transformers.

The cables used in the medium voltage network are 18/30 KV Aluminum cables,

for their lower cost and because the probability of stealing copper cables is high

compared to Aluminum cables.

In the figure 4.1 below, there’s a substation that feeds a number of distributors in

a medium voltage network.

Fig 4.1 Substation feeding some distributors


104

4.2.2 Distributor (MVSG)

It’ the second step in the medium voltage network, as the medium voltage (22

KV). We can consider it a sectionalized busbar supplied from two different 66/22 KV

transformers in the same substation or from different substations to assure the

continuity of supply in case of occurring of a fault in a cable between a transformer

and the distributor, this cable will be disconnected and the distributor will be supplied

from the other transformer and thus helps the reliability of this distributor.

The bar of the distributor will be fed from two different transformers through

medium voltage with-draw able circuit breakers. There is one with-draw able circuit

breaker on the bar called the bus coupler. This circuit breaker splits the bar in two

isolated parts each part is fed from one transformer. In case a fault occurs; this circuit

breaker will connect the isolated parts of the bar (after isolating the faulty feeder) to

feed all loads on the bar of the distributor. This system is known as two out of three

system (2/3 condition). The number of the outgoing feeders connected to the first part

of distributor bar is equal to the number of the outgoing feeders connected to the other

part. One feeder of the first part is connected to other one in the other part through

ring main feeder to make sure that the continuity of supply is achieved. In case of

fault; the ring main has a supply from one of the feeders coming from distributor. The

standard cross section area of the feeder coming from sub-station is (3x1x400) mm²

(AL/XLPE/(18/30)KV/STA) for the two (24 MVA) distributors which is used in this

city , these feeders are always double, and each pair came from different sub-station

or from the same substation as mentioned above. The rule here in Egypt is that each

pair of cables can carry the whole load of the distributor alone in case of loss of the

other pair; that is the feeders are loaded by only 50% of their current carrying capacity

in the normal conditions (when the bus coupler is opened). Loading the cable with

only 50% of its capacity is of course a much exaggerated rule from the economical

point of view and we recommend that the feeder is loaded up to 70% of its capacity.

The outgoing of the two distributors has standard cables (3x240) mm² (AL/XLPE/

(18/30)KV/STA). Each feeder in first part connected to another one on the second

part and forms an open loop. Number of transformers in each loop ranges between

816 transformers. A schematic diagram of the distributor is shown in figure 4.2.

Fig 4.2 The Distributor


105

4.2.3 Distribution Transformer

This transformer is equipped to the ring main feeder through two units of

switchgear (Load break switch, which can switch at light loads), then through a fused

load break switch (which is cheaper than the circuit breaker) to protect the

transformer from over current at fault time. This is known as Ring Main Unit

(R.M.U). Connection of the RMU's to the distributor is shown in figure 4.3.

Fig 4.3 Transformer supplied from RMU

A schematic diagram of the distribution transformer point for 22 KV systems with

all its equipment is given in figure 4.4.a

Fig 4.4.a schematic diagram of distribution transformer


106

A single line diagram of the distribution transformer point for 22 KV systems with

all its equipment is given in figure 4.4.b

Fig 4.4.b Single line diagram of a distribution transformer point

4.3 Medium Voltage Network Types 4.3.1 Medium voltage switchboard supply modes

4.3.1. a One bus bar, one supply source

It consists of 1 supply and 1 busbar, if a fault occurs that lead to unavailability of

supply, then the busbar will get out of service until the fault is repaired and the source

is available again.

Fig 4.5 1busbar, 1 supply source

22 KV

500KVA

22KV/380v


107

4.3.1.b One bus bar with no coupler, 2 supply sources Only one supply feeds the busbar at a time, while the other can be considered a

back up supply, and its advantage is that the busbar is supplied even if one of the

supplies is unavailable. But the disadvantage is in case of a fault on the busbar itself

which rarely occurs, so the outgoing feeders are no longer fed from either of the 2

sources.

Fig 4.6 1 bus bar with no coupler, 2 supply sources

4.3.1.c Two bus sections with coupler, two supply sources

This method is called two out of three operation (2/3 operation), which states that

only 2 of the 3 circuit breakers are closed and the third one is open.

The bus coupler circuit breaker is normally open and each section of the busbar is

fed from its source supply, but if there is a fault in one of the supply, this source is

disconnected and the bus coupler is connected, and both busbar sections are fed from

one source supply, until the faulted source supply is repaired.

The advantages of this method is the continuity of supply to all loads in case of a

fault on one of the sources, but if a fault occurs on one of the bus sections, then the

loads on this bus section are no more fed up from any of the 2 sources.

Fig 4.7 2 bus sections with bus coupler, 2 supply sources


108

4.3.1.d One bus bar with no coupler, three supply sources

The busbar is supplied from 2 parallel connected sources and third one is a back

up on case of loss of one of the two sources. The same problem occurs here which is

the unavailability of supplying the loads in case of a fault on the busbar, or in case of

its maintenance.

Fig 4.8 1 bus bar with no coupler, 3 supply sources

4.3.1.e Three bus sections with couplers, three supply sources

Each supply source feeds its own bus section and the bus couplers are kept

normally open. In case of loss of one of the supplies, the bus coupler associated to it is

closed and so the loads on this bus section are still supplied from another source. But

we suffer also from the same problem in case of a fault on one of the bus sections, and

then the loads connected to it are no more supplied by any of the supply sources.

Fig 4.9 3 bus sections with couplers, 3 supply sources


109

4.3.1.f Two bus bars, 2 connections per outgoing feeder, two supply sources

Each outgoing feeder is supplied by one of the two bus bars, depending on the

state of isolators which are associated with it and only one isolator per outgoing

feeder must be closed.

Fig 4.10 2 bus bars, 2 connections per outgoing feeder, 2 supply sources

4.3.1.g Two interconnected double bus bars

This arrangement is almost identical to the previous one. The advantage of this

arrangement appears from splitting up the double bus bars into two switchboards with

coupler (via CB1 and CB2) which provides greater operating flexibility and facilitates

the maneuver in the network. Another advantage is that each busbar feeds a smaller

number of feeders during normal operation. Of course the reliability increase so much

with this arrangement.

Fig 4.11 Interconnected double bus bars


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4.3.1.h Duplex distribution system

In this arrangement each source can feed one or other of the bus bars via its two

draw out circuit breaker cubicle. For economical reasons, there is only one circuit

breaker for the two draw out cubicles which are installed alongside one another so it

is easy to move the circuit breaker from one cubicle to the other. Thus if source 1 is to

feed BB2, the circuit breaker is moved into the other cubicle associated with source 1.

The same principle is used for the outgoing feeders. Thus, there are two draw out

cubicles and only one circuit breaker associated with each outgoing feeder. Each

outgoing feeder can be fed by one or other of the bus bars depending on where the

circuit breaker is positioned.

Fig 4.12 Duplex distribution system

There are many advantages in this system such as:

If one source is lost, the other source provides the total power supply.

If a fault occurs on one of the bus bars or maintenance is carried out on it, the

coupler C.B is tripped and each circuit breaker is placed on the busbar in

service, so all the outgoing feeders are fed.

This arrangement is very reliable and the power supply continuity is high.

This arrangement is more economic since the amount of switch gear required

is reduced.

4.3.2 Medium voltage network structure

4.3.2.a Radial systems

It consists of a number of feeders getting out radial from a common source, and

the transformers are connected to the taps along the length of feeders.

The main disadvantage of this type is that if a fault occurs on one feeder, all the

loads connected to that feeder will no longer be supplied until this feeder is repaired,

and thus there’s no continuity in the supply.


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Fig 4.13 Radial system

4.3.2.b Loop (Ring) system

The main advantage of this system is the continuity of supply where two feeders

are taken from the same substation to the load. The ring system is a complete loop and

has an isolating switch.

Fig 4.14 Loop system

There are two main types of loop system which are:

I. Open loop

The main switchboard is fed by two sources with coupler.

The loop heads in A and B are fitted with circuit breakers.

Switchboards 1, 2 and 3 are fitted with switches.

During normal operation, the loop is open (on the figure it is normally

open at switchboard 2).

The switchboards can be fed by one or other of the sources.

Reconfiguration of the loop enables the supply to be restored upon

occurrence of a fault or loss of a source.

This reconfiguration causes a power cut of several seconds if an

automatic loop reconfiguration control has been installed. The cut lasts

dozens of minutes if the loop reconfiguration is carried out manually

by the operators.


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Fig 4.15 Medium voltage open loop system

II. Closed loop

The main switchboard is fed by two sources with coupler.

All the loop switching devices are circuit breakers.

During normal operation, the loop is closed.

The protection system ensures against power cuts due to a fault.

This system is more efficient than the open loop since it avoids power

cuts.

On the other hand, it is more costly since it requires circuit breakers in

each switchboard instead of switches in case of open loop system. Also

the protection system is complex.

Fig 4.16 Medium voltage closed loop system


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4.4 Calculation of the distribution point and sizing of the 22 KV

cables This city has transformers of 500 KVA and 1000 KVA rating.

There are two methods to calculate the total load of this city; either to consider the

rating of the transformers or to consider that each transformer is loaded by no more

than 80% of its full load. The second method is to be considered here since it is more

secure.

We’ll use two MVSG each up to 32MVA to supply all these residential loads,

commercial loads and the estimated loads. Each MVSG has three loops, two loops for

the actual loads and one loop for the estimated loads. The estimated loads are shown

in table 4.1 for the first MVSG and table 4.2 for the second MVSG.

Loads area building area estimated KVA/100m² KVA

school 3 20500 12300 3 369

Institute of High 2 6550 3930 3 117.9

school 2 14600 8760 3 262.8

Institute of High 1 5900 3540 3 106.2

Headquarters collectivist 2711 1626.6 3 48.798

school 1 27000 16200 3 486

hotel 5550 3330 10 333

Commercial building 5 6850 4110 6 246.6





club 45212 27127.2 5 1356.36

mosque3 1860 1116 3 33.48

mosque 4 245 147 3 4.41

sum 5664.948

Table 4.1


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Loads area building area estimated KVA/100m² KVA

Commercial building 6 24000 14400 6 864


mosque 1 1500 900 3 27

mosque 2 1150 690 3 20.7

House Decoration 617 370.2 5 18.51

clinic 590 354 5 17.7

school 25125 15075 3 452.25

hospital 23000 13800 12 1656

Administrative building 1 21227 12736.2 5 636.81

Administrative building2 20500 12300 5 615

Administrative building 3 11500 6900 5 345

Administrative building 4 71000 42600 5 2130

Service-based 5200 3120 3 93.6

sum 7582.17

Table 4.2

The MVSG is connected to a number of Ring Main Unit (R.M.U). Each R.M.U

consists of load break switches and fuses .The specifications of the used R.M.U are:

o Load Break Switches: Rated Voltage 24 kV

Basic Impulse Level 125 kV

Power Frequency Withstand Voltage 50 kV

Rated Current 600 A

Rated Short-time Withstand Current 1 sec 20 kA

Rated Making Withstand Current peak 50 kA

Inductive Breaking Current 10 A

Capacitive Breaking Current 40 A for Cable L.B.S.

o Fuse Ratings: Rated Voltage 24 KV

detaR Current 20 or 40 A

Rated Frequency 50 Hz

Rated Breaking Capacity ≥ 40 kA

The transformers connected to the first and the second MVSG are shown in fig 4.17

and fig 4.18 .The single line diagram of first and the second MVSG are shown in fig

4.19 and fig 4.20.


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116


117


118


119

Calculation:

The maximum loads for one loop = 8 MVA

The loads of one of the two feeders of the loop = 4 MVA

So, the feeder current at normal operation = 322

4000 104.97 Amperes

And the maximum feeder current in case of fault = 5.0

97.104 209.94 Amperes

From tables of El Electro Cable Egypt Co.

Cables used have the following properties:

o Voltage Rating: 18/30 KV

o 18/30 KV Multi cores Aluminum conductors, XLPE Insulated, Steel tape

Armored and PVC Sheathed.

o C.S.A.: 22403 mm

o Conductor resistance = km/163.0

Calculation of the voltage drop in the primary distribution network (between the

distributor and the last transformer)

o V.D = 104.97×0.163×0.001×1200m=20.53 volt

o Percentage V.D = 22000

53.20 × 100 =0.0933 %

So, the voltage drop is neglected, since the operating voltage in the primary

distribution network is high (22 KV).

Some notes:

1-We will use what is called TYPICAL DISTRIBUTER ,each contains 12 cell, 4 cells

for input, 6 cells for output , one coupler & one riser, as shown in figure 4.20 .

2- We will use two distributors (MVSG) each up to 32MVA, the four input arms of

(3×1×400 mm²) & the six output arms of 3×240 mm².

66/22 KV SUBSTATION

Chapter 5

CHAPTER 5 66/22 KV SUBSTATION

120

Chapter 5

66/22 KV SUBSTATION

5.1 Introduction

In the previous chapter we have designed the medium voltage network

(MVSG), this network is supplied from 66/22 KV Substations which is our concern in

this chapter, these Substation consisting of one or more transformers (the number of

transformer is preferred to be even), with associated switchgear, protective gear and

control panels .the input power to the substation is from transmission lines.

Transformers substations equipment include bus bars, transformers, High

Voltage transmission lines and cables entrances, Medium Voltage feeders and

switchgear, either at the highest transmission voltage or at lower voltages has two

separate functions, to determine the paths of power flow, and a protective function

which may require it break the fault at the point or which it is situated switchgear

thus, include circuit breakers, isolating switches earthling switches potential and

current transformers, lighting arrestors , ...etc.

5.2 General Overview

At many places in the power system, it is desired to change some characteristics

of the electric power supplied like voltage, A.C. to D.C., frequency, improving power

factor…etc. and that is accomplished in suitable arrangement which we call

substation.

A substation is named according to its function in the power system, for example:

Transformer substation: in which the voltage is changed from one level to

another.

Switching Substation: in which an adequate method is used to switch on the

power lines.

Power Factor correction Substation: this contains condensers for improving

the power factor.

Frequency changer Substation: this is used to change the frequency of the

electric power supply to different frequencies required in different

applications.

Converting Substation: this converts A.C. to D.C. and vice versa which are

used in special applications in the power system.

Chapter 5 66/22 KV SUBSTATION

121

5.3 Substation Classifications

I. Step up substation

It’s located after the generating source of electric power; the voltage is

stepped up in this substation before transmitting this electric power in the

transmission lines. And that helps to decrease the voltage drop in the transmission

lines as well as offering the probability to choose conductors of less c.s.a and less

cost as the current is decreased.

II. Bulk power substation

This substation receives power from the transmission system supplying a

very high voltage (132, 220 or 500 KV) and transformers it to sub-transmission

system having lower high voltage (66 KV).

III. Distribution substation

This substation received power from the sub-transmission system at high

voltage (66 KV) and transforms it to a medium voltage of (11 or 22 KV) to flow

in the primary feeder system.

5.4 Types of substation

I. Outdoor substation

This type is installed outdoor, and it needs more protection against pollution.

It’s used in rural and urban areas where the cost of land is not high and it’s

available.

Its capital cost is less because of the less building needed in it.

Extension in this type of substation will be easy.

Bad weather conditions and rains may cause some problems.

It requires a large space.

Easy to identify fault location as the whole substation can be viewed.

Needs high maintenance and cleaning cost.


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II. Indoor substation

It’s installed inside building and it has fewer problems against pollution.

It’s used in cities and residential areas where the availability of land is low

and its cost is high

Its capital cost is high due to the higher cost of land and the cost of

buildings needed.

Extension in this type of substation will be very difficult.

It will have an easy operation.

It requires a small space.

Difficult to identify fault location.

Needs less maintenance and cleaning cost.

III. Gas Insulated substation (GIS)

Advantages of GIS

Due to insulation (sulpher hexafluoride SF6), the area of the GIS plan is

much less than the area of conventional type, hence it is very suitable for

the high population regions where the cost of land is very expensive. Also

the clearance between each unit and other will decrease hence the area

decreases.

There is a possible leakage of the gas, but its acceptable if occurs in range

1% for one kit and 5% for all kits in substation annually.

All parts of substation inside depth which is filled by SF6, and there is a

manometer for each distance to measure the pressure inside the ducts if it

decreases than that certain limit and steps out the range then it will close

the tripping coil circuit of C.V. hence, the C.B. is opened to protect the

system.

Yet the GIS type is more expensive than other types and needs continuous check that

the SF6 level is within the acceptable ranges.

Anyway, the following points are the requirements of a good substation:

It should be located at a proper site. It is better to be located at the load

center as much as possible.

Circuits are designed so that failure chances become small.

In case of fault; protection switchgear should work correctly.


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Fire extinguishers are installed.

Reactors to limit the short circuit current are used.

It should be easily operated and maintained.

It should involve minimum capital cost.

5.5 Substation layout

The layout of the substation is very important since there should be a Security of

Supply. In an ideal substation all circuits and equipment would be duplicated such

that following a fault, or during maintenance, a connection remains available.

Practically this is not feasible since the cost of implementing such a design is very

high. Methods have been adopted to achieve a compromise between complete security

of supply and capital investment. There are four categories of substation that give

varying securities of supply:

Category 1: No outage is necessary within the substation for either

maintenance or fault conditions.

Category 2: Short outage is necessary to transfer the load to an alternative

circuit for maintenance or fault conditions.

Category 3: Loss of a circuit or section of the substation due to fault or

maintenance.

Category 4: Loss of the entire substation due to fault or maintenance.

Different Layouts for Substations

I. Single Bus bar

The general schematic for such a substation is shown in the figure below.


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With this design, there is an ease of operation of the substation. This design also

places minimum reliance on signaling for satisfactory operation of protection.

Additionally there is the facility to support the economical operation of future feeder

bays.

Such a substation has the following characteristics.

Each circuit is protected by its own circuit breaker and hence plant outage

does not necessarily result in loss of supply.

A fault on the feeder or transformer circuit breaker causes loss of the

transformer and feeder circuit, one of which may be restored after isolating the

faulty circuit breaker.

A fault on the bus section circuit breaker causes complete shutdown of the

substation. All circuits may be restored after isolating the faulty circuit

breaker.

A bus bar fault causes loss of one transformer and one feeder. Maintenance of

one bus bar section or isolator will cause the temporary outage of two circuits.

Maintenance of a feeder or transformer circuit breaker involves loss of the

circuit.

Introduction of bypass isolators between bus bar and circuit isolator allows

circuit breaker maintenance facilities without loss of that circuit.

II. Mesh Substation

The general layout for a full mesh substation is shown in the schematic below.


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The characteristics of such a substation are as follows.

Operation of two circuit breakers is required to connect or disconnect a circuit,

and disconnection involves opening of a mesh.

Circuit breakers may be maintained without loss of supply or protection, and

no additional bypass facilities are required.

Bus bar faults will only cause the loss of one circuit breaker. Breaker faults

will involve the loss of a maximum of two circuits.

Generally, not more than twice as many outgoing circuits as in feeds are used

in order to rationalize circuit equipment load capabilities and ratings.

III. One and a half Circuit Breaker layout

The layout of a 1 1/2 circuit breaker substation is shown in the schematic below.

The reason that such a layout is known as a 1 1/2 circuit breaker is due to the fact that

in the design, there are 9 circuit breakers that are used to protect the 6 feeders. Thus, 1

1/2 circuit breakers protect 1 feeder. Some characteristics of this design are:

There is the additional cost of the circuit breakers together with the complex

arrangement.

It is possible to operate any one pair of circuits, or groups of pairs of circuits.

There is a very high security against the loss of supply.


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5.6 Substation Equipment

To do its task in a proper way, substations contain much equipment. The most

important and common equipment in the transformers substations are the following

1. Bus Bars

When a number of lines operating at the same voltage must be directly connected

electrically, bus bars are used as the common electrical point. Bus bars are rigid

aluminum or copper bars (generally of rectangular cross-section) and operate at

constant voltage and frequency. The incoming and outgoing lines in a substation are

connected to the bus bars. Bus bars receive power from incoming circuits and deliver

power to outgoing circuits.

There are many arrangements of bus bars in substations. Some of them are:

1- Simple single bus bar.

2- Sectionalized single bus bar system.

3- Double bus bar system.

4- Double sectionalized bus bar system.

While the system in (2) is commonly used for medium and low voltages (22KV and

less), the system in (4) is commonly used for high and extra high voltages (66 KV and

more).

2. Insulators

The porcelain insulators employed in the substations are of past and bushing

type. They serve as supports and insulations of the bus bar. A past insulator consists

of porcelain body, an iron cap and a flanged cast iron base.

Bushing insulators are used to pass the conductor through a wall or a tank

transformer. A bushing consists of porcelain shell body and upper and lower locating

washers used for fixing the position of the bus bar or rod in shell. For current rating

above 2 KA, the bushings are designed to allow the main bus bars to pass directly

through them.

3. Lightning Arrestors and Surge Arrestors

Lightning and surge arrestors are shunt resistors used to divert the lightning and

high voltage surges to earth and protect other equipment from H.V surges. They are

connected generally between phase conductor and ground. They are located where the

first equipment is seen from the incoming overhead line and also near transformer

terminals phase to ground. There are two types of surge arrestors; Gapped Arrestors

and Gapless Zinc-Oxide Arrestors.


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4. Isolators (disconnecting switch)

In substation, it is often desired to disconnect a part of the system for general

maintenance and repairs. This is accomplished by an disconnecting switches or

isolators. They are located at each side of the circuit breaker. They are disconnected

after tripping the C.B and closed before closing the C.B. That's why they don't have

any rating for current breaking or current making. From the common types of

isolators: center rotating horizontal swing isolators, vertical swing and pantograph

type isolator (for 420 KV). Isolators are interlocked with circuit breaker

5. Earthing switch

Its function is to discharge the trapped charges on the circuit to earth for safety.

They are mounted on the frame of isolators.

6. Current Transformer (CT)

It is used to step down the current for measurement, protection and control. The

need for a CT comes from the fact that the measuring, control and protection

instruments are designed for working at low ratings (usually 110V and 5A). The C.T

usually has three secondary coils; one for measuring, the 2nd

for protection and the 3rd

for controlling.

7. Voltage (potential) transformer (PT)

It is used to step down the voltage for measurement, protection and control. Its

location is at the feeder side of the circuit breaker. Its secondary voltage is usually 110

V.

8. Circuit Breaker (C.B)

There are two forms of open circuit breakers:

1. Dead Tank - circuit breaker compartment is at earth potential.

2. Live Tank - circuit breaker compartment is at line potential.

Circuit breakers are installed to perform the following duties:

Switching during normal and abnormal operating conditions

Interrupting short circuit currents.

C.Bs are located at both ends of every protective zone. Types of C.B depend on the

rated voltage and the medium of arc quenching. Among the types of C.B: SF6,

Vacuum, Air blast and minimum oil.

9. Power transformers

The power transformer used to step down the voltage from 66 KV to 22 KV.

The common connection of the power transformers is delta/star-earthed to trap the

zero sequence and third harmonic components and prevent them from reaching the

secondary side and thus the distribution networks.


128

The rating of power transformers depends on the loads of the substation zone. In

general the most common used ratings for power transformers used in the distribution

substations are 25 and 35 MVA. Power transformers are usually oil filled. They have

two or three windings. They are provided with coolers.

Power transformers have tapped windings, which permit adjusting the output

voltage to broaden the range of primary voltage inputs. The transformer will have a

manual tap changer, which can be operated if the transformer is de-energized. An

automatic on load tap changing (OLTC) feature installed on a transformer provides

automatic tap changing under load, and normally varies the voltage to 10% of the

system’s rated voltage in steps by changing tap connections using a motor-driven, tap-

changing switch. Sometimes voltage regulation is needed and the system

transformers. Voltage regulators are used to supply the control for the variations in

load.

Industry standards classify transformers as outdoor and indoor transformers. An

outdoor transformer is constructed of weather-resistant construction, suitable for

service without additional protection from the weather.

Several types of transformers are used in substation such as

a) Power Transformers

It is usual to provide some standby plant, since transformers require maintenance

in respect of their cooling system and tap changing equipment , so the operation of

two or three 3-phase transformers in parallel to carry a given load, with one similar

unit as standby, is usually providing 25 or 33 % spare plant capacity.

Power transformers are roughly by their means of cooling and by whether the

circulation of the insulating oil, which is also the cooling medium, takes place by

natural circulation, using the thermal head, or is forced by an external pump.

Power transformers are usually oil immersed with all three phases in one tank.

Auto transformers can offer advantage of smaller physical size and reduced losses.

The different classes of power transformers are:

O.N.: Oil immersed, natural cooling

O.B.: Oil immersed, air blast cooling

O.F.N.: Oil immersed, oil circulation forced

O.F.B.: Oil immersed, oil circulation forced, air blast cooling

Power transformers are usually the largest single item in a substation. For

economy of service roads, transformers are located on one side of a substation, and

the connection to switchgear is by bare conductors. Because of the large quantity of

oil, it is essential to take precaution against the spread of fire. Hence, the transformer

is usually located around a sump used to collect the excess oil.

Transformers that are located and a cell should be enclosed in a blast proof room.


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b) Auxiliary Transformers

To supply all services in substation such as lighting and control circuits.

c) Potential Transformers

It is used just for measurements and protection devices operate under low

voltage.

A Potential Transformer is basically a conventional constant-voltage

transformer with primary and secondary windings on a common core

connected in shunt or parallel to the power supply circuit to be measured or

controlled.

d) Current Transformers

Since measuring and protection devices cannot withstand high current, a current

transformer is used.

A Current Transformer is a constant-current transformer that reduces line

currents into values suitable for standard measuring devices such as ammeters

and watt meters and standard protective and control devices. It also isolates

these devices from line voltages. The primary winding is connected in series

with the circuit carrying the line current.

CT's may be accommodated in one of six manners:

Over Circuit Breaker bushings or in pedestals.

In separate post type housings.

Over moving bushings of some types of insulators.

Over power transformers of reactor bushings.

Over wall or roof bushings.

Over cables.

10. Marshalling Kiosk

They are used in the outdoor substations. They are used to mount both monitoring

instruments and control equipment and to provide access to various transducers.

Marshalling kiosks are located in the switchyard near every power transformer.

They are used in the indoor substations. They are used to house various measuring

instruments, control Instruments and protective relays. They are located in air-

conditioned building. Control cables are laid between switchyard equipment and these

panels.


130

11. Shunt reactors

They are used with extra high voltage transmission lines to control the voltage

during low-load period by compensating the capacitance of the transmission line

during these periods.

12. Series reactors (current limiting reactors)

They are used to limit the short circuit currents and to limit current surges

associated with fluctuating loads.

13. DC Bus bars

The trip coils of all circuit breakers operate using a dc supply, thus we need dc bus

bar in the substation. This is achieved using two auxiliary transformers to step down

from 22 KV to 380 V. These transformers feed two rectifying units supplying two

chargers. These are charging two battery cells which are kept floating on the supply.

If the dc bus bars are de-energized for any reason, the batteries can fill in its place.

The 380 voltage supplies necessary lighting, air conditioning, motors for the cooling

fans and any other auxiliaries.

14. Station Earthing System

It is used to provide a low resistance earthing for doing the following tasks:

discharge currents from surge arrestors, overhead shielding and earthing

switches

for equipment body earthing

for safe touch potential and step potential in substation

for providing path for the neutral to ground currents for the earth fault

protection

5.7Earthing and Bonding

The function of an earthing and bonding system is to provide an earthing system

connection to which transformer neutrals or earthing impedances may be connected in

order to pass the maximum fault current. The earthing system also ensures that no

thermal or mechanical damage occurs on the equipment within the substation, thereby

resulting in safety to operation and maintenance personnel. The earthing system also

guarantees eqipotential bonding such that there are no dangerous potential gradients

developed in the substation.


131

In designing the substation, three voltages have to be considered.

1. Touch Voltage: This is the difference in potential between the surface potential and

the potential at earthed equipment whilst a man is standing and touching the earthed

structure.

2. Step Voltage: This is the potential difference developed when a man bridges a

distance of 1m with his feet while not touching any other earthed equipment.

3. Mesh Voltage: This is the maximum touch voltage that is developed in the mesh of

the earthing grid.

Earthing Materials

1. Conductors: Bare copper conductor is usually used for the substation earthing

grid. The copper bars themselves usually have a cross-sectional area of 95 square

millimeters, and they are laid at a shallow depth of 0.25-0.5m, in 3-7m squares. In

addition to the buried potential earth grid, a separate above ground earthing ring is

usually provided, to which all metallic substation plant is bonded.

2. Connections: Connections to the grid and other earthing joints should not be

soldered because the heat generated during fault conditions could cause a soldered

joint to fail. Joints are usually bolted, and in this case, the face of the joints should be

tinned.

3. Earthing Rods: The earthing grid must be supplemented by earthing rods to assist

in the dissipation of earth fault currents and further reduce the overall substation

earthing resistance. These rods are usually made of solid copper, or copper clad steel.

4. Switchyard Fence Earthing: The switchyard fence earthing practices are possible

and are used by different utilities. These are:

(i) Extend the substation earth grid 0.5m-1.5m beyond the fence perimeter.

The fence is then bonded to the grid at regular intervals.

(ii) Place the fence beyond the perimeter of the switchyard earthing grid and

bond the fence to its own earthing rod system. This earthing rod system is

not coupled to the main substation earthing grid.

5. Neutral Grounding Equipment

They are either resistors or reactors. They are used to limit short circuit current

during ground faults. They are short time rated. They are connected between neutral

point and ground.


132

5.8 Essential Civil Structure in outdoor substations

The following civil structures are necessary in a conventional outdoor substation:

Towers of incoming and outgoing transmission lines. These are generally

located outside the substation boundary, adjacent to the substation.

Towers (columns) and beams (gantries) for supporting strain conductors, and

flexible bus bars. These are used for mounting isolators, surge arrestors and

other equipment. Suitably; thereby eliminating additional separate

foundations.

Towers and gantries for supporting rigid tubular bus bars mounted on post

insulators. These insulators are supported on horizontal beams (gantries).

Support structures for post insulators which support the tubular rigid bus bars.

Support structures for mounting the substation equipment such as CTs, VTs,

isolators, circuit breakers, etc.

Supporting structures for auxiliaries such as cooling water system, fire

fighting system, etc.

The major items of the substation such as transformers and circuit breakers are

usually mounted on reinforced cement concrete plinths at ground level

5.9 Description of the Single Line Diagram and Layout for

the Present 66/22KV Substation

Figure which presents the single line diagram of the 66/22KV substation that

feeds the residential area in our project shows that the substation consists of a

sectionalized double bus bar system fed by six 66KV cables, two incoming from the

preceding substation in the 66KV ring and two are outgoing to the next substation in

the ring and remains two 66KV feeder cells as reserve.

The bus bar sections are coupled near a bus coupler consisting of a circuit breaker

and two isolating switches, together with four isolating switches dividing the bus bars

into four sections.

Four 66/22KV, 35MVA transformers are fed from the bus bars, and are connected

in parallel groups or each to a separate section of the bus bars. The transformer

connection circuit to the bus bar, as well as the feeder connection circuit, consists of a

66KV circuit breaker with two isolating switches towards the bus bars and one after

the circuit breaker on the other side.

Current and potential transformers are connected in the circuits for the objectives

of protection and measuring.

The transformers are connected via circuit breakers to the 22KV sectionalized bus

bar. This is cut into four sections coupled with four bus couplers. Outgoing 22KV

feeders come out of the 22KV bus bar sections, running outside the substation to feed


133

the distribution points as well as some loops of distribution transformers and some big

consumers directly.

Two auxiliary transformers are fed from two different sections of the 22KV bus

bar. The ratings of these are 500KVA, 22/380KV in order to feed the substation

services; lighting, compressors, rectifiers to supply dc batteries, etc.

The figure while presents the layout of the substation on a plan at the ground level

indicates the substation arrangement. Four rooms for the four main transformers as

shown on one side of the 66KV-switchgear hall.

Meanwhile, the 22KV switchgear hall, the control room, the auxiliary

transformers room, as well as other service areas and the stairs are shown on the other

side. Above this several offices are arranged as well as the rest of services rooms,

which could be shown on anther plan at the level of the first floor.

The 66KV bus bars could be shown on a third plan at a higher level.

The figure which presents cross sections in two 66KV cells, one for a feeder

cell, the other is for a transformer cell. These side views describe clearly the circuit

connections of the 66KV feeder and the 66/22KV transformers to the 66KV bus bars.

They also show clearly the arrangement of the various apparatus in the circuit; the

circuit breakers, the isolating switches, the potential and current transformers.

Further, the single line diagram as well as the substation layout show lightning

arrestors to protect the substation from lightning surges, in the case of overhead

transmission lines feeding the substation.

Earthling switches are also connected to the 66KV and 22KV feeders to ground

these before carrying out maintenance or repair. Interlocks are provided between these

earthling switches and the respective circuit breakers.

POWER SYSTEM PROTECTION

Chapter 6

CHAPTER 6 POWER SYSTEM PROTECTION

134

Chapter 6

POWER SYSTEM PROTECTION

6.1 Introduction

There is a great importance of protection of power system and this importance

clearly appears though:

1. Ensuring the reliability and continuity of supply to different loads.

2. The large amount of capital investment in the power system justifies the

importance of protection.

So, we shall care for protecting every part in the power system to save ourselves,

to save the expensive components in the power system and to ensure the reliability of

supply in this system.

6.2 General Overview

Effect of short circuit currents on power system:

The fault current could be several thousands of amperes, which has a heating

effect and could result in melting of conductors or insulation failure.

Short circuits are associated with arcs which lead to fires.

Excessive currents lead to excessive forces between conductors, busbars,

transformers and coils.

When a fault occurs, the voltage drops to zero causing the nearest generating

station to go out of step.

In oil transformers, bubbles maybe formed which may lead to arc occurrence

and possibility of explosion.

As a result we should make a design for a good protective system which can

ensure a safe operation of the power system.

Requirements in any protection system:

1. Fast acting(speed): when a fault occurs, the protection system should clear that

fault as quickly as possible.

2. Sensitive: it should be sensitive to all kind of faults.

3. Reliability: the protection system should be reliable.

4. Selectivity (Discrimination): the protection system should be selective where

only faulty sections should be isolated.

5. Economical.

6.3 Types of faults in power systems

The faults in a power system can be classified into:

1. Symmetrical faults

2. Unsymmetrical faults


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6.3.1 Symmetrical faults

Fig 6.1 Symmetrical fault

It occurs when the three phases are connected together and to the ground.

It’s the most severe fault (has maximum short circuit current).

It’s the least probable type of fault (probability of happening is very small~5%).

It’s used to determine the breaking (rupturing) capacity of circuit breakers.

6.3.2 Unsymmetrical faults

a) Line to Ground fault

Fig 6.2 Line to Ground fault

It occurs when a conductor of one phase touches the ground.

It’s the most common type fault (probability of occurrence equals about 80 % of

faults).

It results from flashover on insulator string.

b) Line to Line fault

Fig 6.3 Line to Line fault

It occurs when conductor of different phases touch each others.

Probability of occurrence equals about~15% of faults.

c) Line to Line to Ground fault (Double Line to Ground fault)


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Fig 6.4 Double Line to Ground fault

This is similar to line to line fault but also involves a fault to earth.

Probability of happening is small.

6.4 Division of power systems into protective zones

6.4.1 Defining protective zone

It’s a part of the power system protected by circuit breakers, such that in case of

fault occurrence inside it, only that faulted part is isolated and the remainder of the

system remains in normal operation.

6.4.2 Advantages of division of power system into protective zones

It can be used for circuit switching during normal operation.

It limits the damage caused during faults or overloads and minimizes its effect

on the remainder of the system.

And this is what is called Selectivity or Discrimination of the protection system.

Fig 6.5 Overlapping of protective zones


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6.5 Fuses

Fuses are the oldest and most simple protective devices. When the current

flowing through the fuse exceeds a predetermined value, the heat produced by the

current in the fusible link melts the link and interrupts the current. Since the current

must last long enough for the link to melt, fuses have inherently a time delay.

Fuses are relatively economical devices, they do not need any auxiliary devices

such as instrument transformers and relays, they are reliable, and available in a large

range of sizes. Their one disadvantage is that they are destroyed in the process of

opening the circuit, and then they must be replaced.

There are four quantities that are important for a particular fuse

application

I. Maximum Rated Voltage

Is the highest nominal system voltage at which the fuse can be used. The

voltage is given as an r.m.s and line to line value. The idea is that a blown fuse

should be able to withstand the system voltage.

II. Maximum Continuous Current

is the maximum r.m.s current the fuse should be able to carry indefinitely. This

current is given by an allowable temperature rise for the fuse, and therefore it also

depends on the ambient temperature.

III. Maximum Interrupting Current

is the largest current the fuse is capable of interrupting. This value should be higher

than the maximum possible fault current on this circuit.

IV. Time Response

This is given by the time-current characteristic. Medium voltage fuses are available

up to voltages of 36 kV for indoor use, and up to 161 kV for outdoor use.

Classification of fuses

I. Non-time delay fuses

The Non-time delay fuse consists of a single type of fusible element, called a short

circuit element. Normal overloads and current surges often cause nuisance openings

of this type of fuse.

Therefore, Non-time delay fuses should be used only in circuits with noninductive

loads such as circuit breaker back-up protection.


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II. Time delay fuses

The time delay fuse is constructed with two different types of fusible elements:

overload and short-circuit.

The overload element will interrupt all overload currents, and the short-circuit

element will open in response to short-circuit currents. The time delay fuse can be

applied in circuits subject to normal overloads and current surges (e.g., motors,

transformers, solenoids, etc.) without nuisance opening.

III. Current-limitation

Current-limiting fuses are so fast acting that they are able to open the circuit and

remove the short-circuit current well before it reaches peak value. Current-limiting

fuses “limit” the peak short-circuit current to a value less than that available at the

fault point and open in less than one-half cycle. To be effective, however, such fuses

must be operated in their current-limiting range.

IV. Medium-voltage fuses

There are two categories of the medium voltage fuses

Distribution fuse cutouts: developed for overhead distribution lines

Power fuses: developed for substations applications. Power fuses are

available at higher voltage and current ratings than the distribution fuse

cutouts.

They come in two types:

1. Current limiting fuses

2. Solid material fuses

V. High-voltage fuses

Some medium-voltage fuses and all high-voltage fuses are rated for outdoor fuse

use only.

VI. Current-limiting power fuses

Current-limiting power fuses are suitable for use on medium-voltage motor

controllers only.

6.6 Basic elements of protective switchgear

The main components of switchgear are:

1. Relays

2. Current Transformers (C.T.)

3. Potential (Voltage) Transformers (P.T. or V.T).

4. Circuit Breaker


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5. Tripping coil of circuit breaker

6. D.C. supply for energizing the tripping coil of circuit breaker

Fig 6.6 Main components of protective switchgear

6.7 Relay

It’s a device which senses the abnormal condition of the power system, sends

signal to the circuit breaker to open the circuit. Relays can’t operate on power system

voltages and currents, therefore current transformers (C.T.) and potential transformers

(P.T.) are used.

6.7.1 Operation of Relays:

When the current in the main line exceeds a certain value, the current in R

increases.

The relay contact (R.C.) closes the circuit of the tripping coil (T.C.).

The T.C. opens the contacts of the circuit breaker which opens the circuit.

6.7.2 Development of Relays

6.7.2.a Electromechanical Relays

Most common type used.

Converts the electrical signal to a mechanical motion, closing or opening the

contacts of the relay.

Simple in operation.

Most widely used.

Operate by electromagnetic attraction or electromagnetic induction.


140

Advantages:

Not expensive.

Simple in construction.

Easy in adjustment.

Disadvantages:

Maintenance required due to movements of relay parts.

6.7.2.b Static Relays

Involve no motion inside the relay.

Consist of electronic circuits (diodes, transistors, etc…).

Advantages:

Lower power consumption therefore current and potential transformers are of

smaller ratings.

Mechanical problems are eliminated.

Disadvantages:

Very sensitive to voltage transients and spikes of small duration can damage

the semiconductor.

Sensitive to changes in the temperature.

6.7.2.c Digital Relays

Consist of digital circuits (AND, OR …gates).

Almost disappeared now.

6.7.2.d Programmable (Microprocessor) Relays

Can be programmed by certain software.

Has an interface with the user such that the setting of the relay can be changed.

Multi-function relays.

6.7.2.e Artificial Intelligence Relays

These relays employ an artificial intelligence (AI) technique for its operation.

Examples are: Neural Network, Fuzzy System, Expert Systems, and Genetic

Algorithms.

6.7.3 Classification of Relays

Relays are classified according to:

6.7.3.a Construction of the relay.

Solenoid type.

Attracted Armature type.

Balanced beam type.

Induction type.


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6.7.3.b Function of the relay:

Over-current relays

Over-voltage relays

Under-voltage relays

Directional power relays

Distance relays

Phase balance relays

6.7.3.c Time characteristics of the relay:

Instantaneous: complete operation occurs after a negligible small interval of

time.

Inverse time lag: time of operation is approximately inversely proportional to

the magnitude of current or other quantity causing operation.

Definite time lag: time of operation is independent on the magnitude of current

or other quantity causing the operation.


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6.7.4 Types of Electromechanical Relays

6.7.4.a Solenoid Type Relay

When a current passes in the coil, a force is exerted on the plunger.

The plunger moves and closes the relay contacts which energize the trip coil

of circuit breaker.

It has instantaneous time characteristics.

Relay Adjustment:

- Taps on the coil.

- Initial plunger position.

- 0i Minimum current to operate the relay.

Fig 6.7 Solenoid Type Relay


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6.7.4.b Balanced Beam Relay

It consists of a balance beam with a spring on one side and electromagnet on

the other side.

When the current is below the set value, the spring force and the force of

electromagnet are equal and the beam is balanced.

If the current exceeds the set value, the force of electromagnet overcomes the

spring force which closes the relay contacts and energizes the trip coil of

circuit breaker.

It has instantaneous time characteristics.

Relay Adjustment:

- By adjusting the air gap between the magnet and the iron piece.

- By using coil taps.

Fig 6.8 Balance Beam Relay


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6.7.4.c Attracted Armature Relay

The electromagnet attracts the armature which closes the relay contacts,

energizing the tripping coil of circuit breaker.

0i Minimum value of current after which the relay starts to operate.

It has inverse time characteristics.

Fig 6.9 Attracted Armature Relay

6.7.4.d Induction Relay

It is the most widely used relay because of their reliability.

It has more flexibility in coordination with other relays or fuses.

It has an inverse time characteristics.

Induction relays include the following types:

i. Induction Disc Type Relay

- A.C. current is supplied to the lower pole, by induction to the upper pole

directly or through a saturating transformer.

- The upper pole induces currents in the disc, and torque is produced by the

reaction between currents and flux from the lower pole.

- Current setting: by adjustment of the coil taps.

- Time setting: by adjustment of the contact travel.

- Breaking (Damping) magnet: its function is to give an eddy current breaking

effect to relay movement.

- This relay will operate only as long as the fault still exists.


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Fig 6.10 Induction Disc Type Relay

ii. Induction Disc Directional Power Relay

- The operating torque is produced by the interaction of magnetic fields derived

from both the voltage and current sources of the circuit it protects. A relay of

this type is essentially a wattmeter and the direction of torque set up in the

relay depends on the direction of current relative to the voltage. The voltage

coil is connected either directly or through a voltage transformer to the circuit

voltage source.

- Directional power relays are normally used for controlling the flow of power

in a circuit under normal load conditions or the reverse power protection of

synchronous machines. Figure 6.11 shows a schematic of this type of relay.

Fig 6.11 Induction Disc Directional Power Relay


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iii. Induction Type Three Phase Balance Relay

- Figure 6.12 shows the main constructional features of this relay. Contacts are

usually open and the spring makes the disc in a central position. For

appreciable unbalance of load on phases a, b, the contacts will close either due

to the right or left movement of the disc. A second disc on the same shaft is

mounted to provide means of response for any appreciable unbalance between

phases a, c.

Fig 6.12 Induction Type Three Phase Balance Relay


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iv. Impedance (Distance) Relay

- The balance beam has an operating coil on one side and a restraining coil on

the other side. The operating coil operates by the current I, whereas the

restraining coil operates by the voltage V.

- The balance point, i.e. the critical impedance value Zo could be adjusted by

current coil taps and by the air-gap adjustment. The balance point, i.e the

critical impedance value Zo is the impedance above which the relay will not

operate.

- The impedance relay is suitable for long lines. However, for short lines the

effect of a resistance may give false indication for the value of (Z) seen by the

relay. To overcome this, reactance relays are used. Reactance relays operate

when X= constant. Figure 6.13 shows the construction and the impedance

diagram of the impedance relay.

Fig 6.13 Impedance Relay


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6.8 Differential Protection of Power systems

If a fault occurs on any section of a transmission or distribution system, it is

essential that the faulty section should be rapidly isolated automatically from the

remainder of the network, hence preventing the damage resulting from the fault and to

localize the area of disturbance.

The ideal characteristics of switchgear are:-

It must be sufficiently sensitive to detect the presence of a fault.

It must discriminate between currents fed to faults in different sections in

order to prevent the isolation of healthy feeders.

It must operate in the shortest possible time.

It must be absolutely reliable in operation, simple and robust.

Protective system may be divided broadly into two broad classes: namely pilot

systems and pilotless systems. Pilot systems are those which employ pilot wires. In

general, pilot systems are more simple and reliable than pilotless systems, but the cost

of pilot wires limits their use on long transmission lines.

6.8.1 Merz-Price differential protection

This method of protection is based on the fact that the current entering one end of

a healthy feeder is equal to that leaving the other end. If a fault occurs, this equality

will not be maintained and the difference between the two currents is arranged to

operate relay which consequently trips the circuit breaker and hence the faulty section

is isolated.

There are two methods for applying the Merz price differential protection; namely

the circulating current method and the opposed voltage method.

Circulating current method

In the circulating current method, the current in the secondaries of the two

identical C.Ts will circulate in the pilot wires and no current will pass in the relay.

However, if an internal fault occurs, the difference in the currents in the secondaries

of the current transformers will operate the relay. Figure 6.14 shows the principle of

the circulating current method.

Fig. 6.14 Circulating Current method, Differential protection.


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Opposed voltage method :

In the opposed voltage method, the secondaries of the identical C.Ts are

connected in series together through relays by means of pilot wires. Under healthy

conditions, the secondary voltages of the C.Ts are in phase-opposition hence balance

each other and no current passes in the relay. If a fault occurs on the line, the currents

at both ends will no longer be equal and hence the induced e.m.f. in the C.Ts

secondaries will no longer balance, thus causing the flow of current in both relays.

Each relay closes its local circuit, energizing the trip coils which opens the C.B.

In order that the C.Bs shall balance as regard to both voltage and phase angle for

all primary current up to high current values, e.g. several thousands amperes, it is

necessary to prevent saturation of the iron core by providing a number of air-gaps in

the iron circuit. Figure 6.15 shows the schematic of this method.

Fig. 6.15 Opposed Voltage method, Differential protection

Advantages of Merz Price system

The operation is reliable.

The discrimination is ideal.

No potential transformers are required.

The operation is practically instantaneous.

The method is applicable to all kinds of systems, e.g. overhead lines,

underground cables, alternators, transformers, etc.

It operates for all types of faults whether to earth or between phases.

Disadvantages of the Merz Price system

The cost of the pilot wires is considerable especially for the long distance

transmission.

The possibility of operation by heavy through currents due to the capacitances

of the pilot wires. Such currents may induce voltage of about 1000 volts or

more in pilot wire circuit. Therefore, to prevent the resulting capacitance

current from operating the relays, the setting of the relay must be higher than

is desirable.

Frequent testing of the pilot circuit is necessary, since no warning would be

given for the break in the pilots, as these normally carry no current.

The C.Ts used should give exactly equal currents in their secondaries or else

the system operates in a wrong way. This is treated by using the biased beam

relay (sometimes called percentage differential relay)


150

6.8.2 Biased Beam relay:

The disadvantage of the current differential protection is that current transformers

must give identical secondary currents; otherwise there will be current flowing

through the current relays for faults outside of the protected zone or even under

normal conditions. Sensitivity to the differential current due to the current transformer

errors is reduced by biased beam relays (sometimes called percentage differential

relays).

The biased beam relay is a circulating current method but with an additional

restraining coil which carries both circulating currents 1i and 2i Thus if the main

current is large, there is a comparatively large restraining force which cannot be

overcome by an error in the C.Ts.

The relay operates when the ratio of the difference ( 1i - 2i ) to the currents 1i or 2i

exceeds a certain minimum value which is adjustable by varying the number of turns

of the restraining coil (R.C). A schematic diagram of this method is given in figure

6.16

Fig. 6.16 Biased Beam relay

Advantages of this system

Since the relay operates on the percentage of the difference, settings down to

5% or 10% can be used without the risk of faulty tripping due to the through

currents. This means more sensitivity of the gear.

Ordinary C.Ts are used.

The pilot capacitance current flows through the restraining coil and will

actually produce a stabilizing effect.


151

6.9 Applications:

6.9.1 Protection of Bus bars:

Differential Protection is applied to bus-zones, because of its great selectivity. A

simple method of bus-bar protection is by comparing the vector sum of currents

entering and leaving the bus zone.

Figure 6.17 shows bus-zone protection, two incoming supplies, based on the

circulating current method. Current will pass in the relay only in case of a fault on the

bus-bar .The same principle can be applied for any number of incoming supplies. The

relay current will be equal to zero as long as there is no fault on bus-bar zone.\

Fig. 6.17 Differential Protection of Bus bars

The following relays are installed in each busbar section of switchboard:

Under-voltage relay: A stationary under-voltage situation shall initiate tripping

of the connected motors.

Frequency relay: Input to Load Shedding System.

Arc detection relay: An arc detection system is installed either alone or in

combination with a current relay. Detection will sectionalize the busbar and

trip the incomer(s). This is not applied for single-phase air or gas (SF6

=Sulpher Hexa-florid) insulated switchboards.


152

6.9.2 Graded type over current protection:

In these systems each relay is assigned a certain time setting. The most important

types of graded type over current protection are the following:

6.9.2.a Radial feeder protection

In the protection of radial feeders in series, relays are adjusted to have a

decreasing time setting with the increase of distance from the generating station. The

time to clear a fault (clearing time) is the sum of the times occupied in operating the

relays, energizing the tripping coils, moving the circuit breaker’s parts and

extinguishing the arc in the circuit breaker. Thus a fault on feeder between S/S 2 and

S/S 3 will results in the operation of relay R3 in a time of 1 second, as shown in figure

6.18

Fig. 6.18 Graded Type Over-current protection

(Radial feeder protection)

Disadvantages of this system

Not very sensitive.

To obtain proper discrimination, the minimum lag between operating times of

relays should not be more than 0.25 to 0.5 second. This limits the number of

relays in series to a maximum of six, since a short circuit should not be kept on

the generator for longer than 2 seconds.

The maximum fault current generally occurs at the generating end of the

feeder where the need of high clearing speed is the greatest, but actually the

time delay is maximum.


153

6.9.2.b Protection of ring main:

The ring main system is an interconnection between a series of stations by means

of which provision is made for alternative routes of power supply without the

necessity for running feeders in parallel. If there is no reversal of power in any section

under normal operating conditions, then a series of directional relays with graded time

lags can be used. The grading is done in clock wise and anti-clockwise direction as

shown in figure 6.19

Each substation is protected by 2 relays, the one with the lower time setting being

directional and operates only for fault currents in the direction of arrow. With a fault

on any feeder section, this section only is isolated and all loads are still supplied

without any interruption of service.

Fig. 6.19 Graded Type Over-current protection.

(Ring Main system)

The disadvantage of this system is the same the previous one, plus the additional

one of using potential transformers that are necessary for the directional relays.


154

6.9.3 Transformer protection:

Differential protection is applied for transformers. The difference in the current

magnitudes of the primary and the secondary windings of the main transformer is

corrected and taken into account by adjusting the turns ratio of the current

transformers.

For three phase transformers, the connection of the current transformers depends

on the connections of the main transformer.

Figure 6.20 shows a typical scheme for a Y/Δ transformer. In order to account for

the phase shift of current in the secondary winding of the main transformer, the C.Ts

are connected as Δ/Y, i.e. on the delta connected side of the main transformer, the

C.Ts are connected to star and vice versa. It can be proven that the currents in the

pilot wires are exactly in phase opposition. Hence their summation at the relay (R)

will be zero i.e no current will pass in the relay. Thus under normal conditions no

current will pass in the relays.

Fig. 6.20 Protection of Y/Δ Transformer

For Y/Y power transformers, the C.Ts are connected as Δ/ Δ. For an internal fault,

the relays will operate and the tripping coils (T.C) at the both ends will be energized;

hence C.Bs at both ends will trip. This is shown in figure 6.21

Fig. 6.21 Protection of Y/Y Transformer


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The Bucholz relay

This relay is fitted to most oil –filled transformers. It is fitted in the oil pipe

between the transformer tank and the oil conservator. Figure 6.22 shows a sketch of

the internal construction of the Bucholz relay.

Under healthy conditions, the relay is full of oil, and hence the mercury switch is

open, since the ball float is at its highest position. If there is any partial failure of the

insulation anywhere inside the transformer, gas will accumulate at the top of the relay.

Hence the ball float will drop down causing operation of the alarm mercury switch

M.S1 causing the alarm (visual or audible) to start.

If there is a short circuit inside the transformer, the explosion will instantly force

the oil against the plate P and thus closes the mercury switch which will trip the C.B.

Fig. 6.22 Bucholz Relay.

6.10 Circuit Breakers

Circuit breakers are used to control the flow of power in power systems and also as the disconnecting equipment when high faults occur on power systems. Circuit breakers then must be capable of performing switching operations on power systems under both, normal and short-circuit conditions .

Requirements put on every circuit breaker

- It must be a perfect conductor in the closed position

(Z = 0) .

- It must be a perfect insulator in the open position

(Z = infinity).

- It must be fast when closing. Current starts flowing before the contacts actually touch and slow closures could damage the contacts.

- It must be fast when opening but it must not extinguish current before its zero crossing and it must not produce over voltages.

B: Float Ball MS: mercury switch P: Plate


156

Classification of Circuit Breakers:

Classification of circuit breakers in common use is done according to the medium that is used to interrupt the arc. Thus the breakers are classified as:

I. Air Circuit Breaker

Interruption of the circuit by using separation of contacts in air was sufficient, although this process drew arc and was damaging to the contacts of the switches. air blast breakers were also developed. The design followed two diverging paths. One was to design a single break breaker for a high voltage (up to 110 kV); the other was to connect several lower voltage (about 35 kV)

II. Oil Circuit Breaker

The mineral oil was held by a steel tank. there were made improvements to the plain break circuit breakers by providing arc and pressure control by enclosing the arcs inside arc pots

III. Sulpher Hexafluoride Circuit Breaker

Sulphur hexafluoride (SF6) was introduced as an interrupting medium. The initial tendency was to use the design of air blast breakers and the SF6 gas was blown under high pressure into the arc. The latest design is towards lower pressure SF6 breakers (these are called puffer type).

IV. Vacuum Circuit Breaker

The main problem was in joining the metal bellows enabling motion of the moving contact, and the ceramic container enclosing the contacts and the arc during breaker opening. The loss of vacuum resulted in explosions, and then in a great reluctance to accept the improved vacuum breakers.Vacuum breakers are now extensively used up to voltages of about 33 kV.

Circuit Breaker Ratings

1) Rated Voltage

Highest r.m.s voltage for which the circuit breaker is designed and is the upper limit for continuous operation.

2) Rated Current

The maximum r.m.s current, which the breaker is capable of carrying continuously without exceeding the given temperature, rise at the given ambient temperature.

3) Rated Frequency

Frequency at which the breaker is designed to operate (60 Hz in North America).

air_breakers.htm

air_breakers.htm

air_breakers.htm


157

4) Rated Interrupting current

Current at instant of contact separation. The interrupting current rating can be given as one of the following values.

5) Symmetrical Interrupting Current

RMS value of the A.C. component of the short circuit current the breaker is capable to interrupt.

6) Asymmetrical Interrupting Current

RMS value of the total short circuit current the breaker is capable to interrupt. This includes the dc and ac components.

7) Rated Making Current :

RMS value of the short circuit current on which the breaker can safely close at the rated voltage.

8) Rated Short Time Current

RMS value of current that the circuit breaker can carry in a fully closed position without damage for a specified short time interval. Normally given for 1s or 4s. These ratings are based on thermal limitations.

9) Rated Impulse Withstand Voltage BIL (Basic Insulation Level)

Maximum short duration impulse voltage tat the breaker can withstand. BIL is tested with a prescribed shape and duration of the test impulse voltage.

STREET LIGHTING

Chapter 7

CHAPTER 7 STREET LIGHTING

158

Chapter 7

STREET LIGHTING

7.1 Introduction Lighting is a vital rule to describe the importance of major and minor roads, which

constitute the lifelines of communication in the motorized world today.

For these roads, to fulfill their function properly, they must be made as safe as

technological and economic resources will permit .Lighting for guidance, lighting to

reveal all the features of roads and point up hazards. Lighting to aid perception and

provide clear visual information for both drivers and pedestrians.

So we can say that the basic purpose of street lighting is to promote safety and

convenience on the streets at night through adequate visibility, and to promote civic

progress. Statistics show that good street lighting installations results in:

Reduce traffic accidents

Respect the environment

7.2 Classification of factors affecting the design of street lighting 7.2.1 Area classification

7.2.1.a Commercial

That portion of a municipality in a business development where ordinarily there

are large numbers of pedestrians during business hours. This definition applies to

densely developed business areas outside, as well as within, the central part of a

municipality. The area contains land use, which attracts a relatively heavy volume of

nighttime vehicular and/or pedestrian traffic on a frequent basis.

7.2.1.b Intermediate

That portion of a municipality is often characterized by a moderately heavy

nighttime pedestrian activity such as in blocks having libraries, community recreation

centers, large apartment buildings or neighborhood retail stores.

7.2.1.c Residential

A residential development or a mixture of residential and commercial

establishments is characterized by a few pedestrians at night. This definition includes

areas with single family homes, town houses, and/or small apartment buildings.

7.2.2 Roadway classification

7.2.2.a Freeway

It’s a divided major roadway with full control of access and with no crossings at

grade. This definition applies to toll as well as non-toll roads.

7.2.2.b Expressway

It’s a divided major roadway for through traffic with partial control of access and

generally with interchanges at major crossroads. Expressways for non-commercial

traffic within parks and park-like areas are generally known as parkways.

11.2.2.c Arterial

The part of the roadway system that serves as the principal network for through

traffic flow. The routes connect areas of principal traffic generation and important

rural highways entering the city.


159

7.2.2.e Local

Roadways used primarily for direct access to residential, commercial, industrial,

or other abutting property. They do not include roadways carrying through traffic.

Long local roadways will generally be divided into short sections by collector

roadway systems.

7.2.2.f Alleys

These are narrow public ways within a block, generally used for vehicular access

to the rear of abutting properties.

7.3 Street lighting arrangements 7.3.1 Two way traffic roads

There are four basic types of street lighting arrangements, which we can

summarize in the following points.

7.3.1.a Single sided

This type of arrangement, in which all luminaries are located on one side of the

road, is used only when the width of the road is equal to, or less than the mounting

height of the luminaries.

This is shown in fig 7.1.

Fig. 7.1 Single sided arrangement

7.3.1.b Staggered

This type of arrangement in which the luminaries are located on both sides of the

road in a staggered, or zigzag, arrangement is used mainly when the width of the road

is between 1 to 1.5 times the mounting height of the luminaries. This is shown in fig

7.2.

Fig. 7.2 Staggered arrangement


160

7.3.1.c Opposite

This type of arrangement, with the luminaries located on both sides of the road

opposite to one another, is used mainly when the width of the road is greater than 1.5

times the mounting height of the luminaries.

Fig. 7.3 Opposite arrangement

7.3.1.d Span wire

This type of arrangement, with the luminaries suspended along the axis of the

road, is normally used for narrow roads that have buildings on both sides.

Fig. 7.4 Span wire arrangement

7.3.2 Curves

Curves of large radius (in the order of 300 m) can be treated as straight roads and

the luminaries can be sited in accordance with one of the schemes outlined above.

The locations of luminaries on curves of smaller radius, however, should be such

as to ensure both adequate road-surface luminance and effective visual guidance.

Where the width of the road is 1.5 m less than the mounting height, the luminaries

should be placed above the outside of the curve in a single sided arrangement.

For wider roads an opposite arrangement should be used since the staggered

arrangement gives visual guidance, and should therefore be avoided.

7.4 Street lighting design process The illumination design process involves the selection of the proper lighting

equipment and the establishment of the geometry of the system in order to provide the

most effective lighting system to satisfy the needs.


161

7.4.1 The major steps of the design process are outlined as follows:

7.4.1.a Existing conditions

Determination of roadway facility and land use area classifications.

7.4.1.b Selection of illumination level

The recommended average intensity of horizontal illumination may be determined

based upon the classifications of roadway facility and area type .Table 7.1 shows the

recommended average maintained illumination (in foot candles).

The precise method of measuring light levels uses the foot-candle, the amount of

illumination provided by a single lumen distributed over a foot-square surface.

VEHICULAR

ROADWAY

CLASSIFICATION

AREA CLASSIFICATION

Commercial intermediate Residential

Freeway 0.6 0.6 0.6

Expressway 1.4 1.2 1

Major ( arterial ) 2 1.4 1

Local 0.9 0.6 0.4

Alley 0.6 0.4 0.4

Table 7.1 recommended average maintained illumination (in foot candles).

7.4.1.c System characteristics

Detailed calculations using selected lighting source types and sizes and luminaries

mounting heights and spacing locations are employed in order to determine the

average intensity of horizontal illumination. The uniformity of illumination is checked

by comparing the ratio of average maintained illumination to minimum maintained

illumination, commonly referred to as the uniformity ratio, with the recommended

criteria in order to determine optimal effectiveness of lighting system.

In our project ,we use two types of lighting poles of different mounting height .the

first one is 12 meter(mounting height) used for express way and arterial streets and

arranged usually in staggered or opposite sided system .the second type is used for

local streets and alleys and this type is a single sided arrangement.

e.g. the following figure illustrates one of the lighting poles.

Fig. 7.5 pole of 8m


162

Checking illumination of local street, single sided arrangements

Calculation field test using DIAlux program

Valuation Field Roadway 1 & Sidewalk 1

Length: 30.000 m, Width: 14.000 m

Grid: 10 x 10 Points

Accompanying Street Elements: Roadway 1, Sidewalk 1.

Selected Lighting Class: CE5 (All lighting performance requirements are met).

Eav [lx] U0 (uniformity)

Calculated values: 27 0.4

Required values according to class: ≥ 7.5 ≥ 0.4

Fulfilled/Not fulfilled:

7.5 Types of lamps used in Street lighting We have to choose suitable kinds of lamps for different streets. The lamp must be

convenient for vehicles and pedestrians.

In internal streets, it’s recommended to use mercury lamps to give a white color,

with enough levels of average luminance to promote civic progress, and ensure

pedestrians safety.

On highways, where there are no pedestrians, we use high-pressure sodium lamps.

Its yellow light is suitable for such kinds of lighting, even in cloudy weather. The

human eye is very sensitive to yellow light, e.g. TPP- 250 watt, 33200Lm, 118

Lm/watt.

Article No.: Philips SRS427 1xSON-TPP250W P9

Luminary Luminous Flux: 33200 lm

Luminary Wattage: 274.0 W

Luminary classification according to CIE: 100

CIE flux code: 38 75 97 100 80

Fitting: 1 x SON-TPP250W/- (Correction Factor 1.000).

7.5.1 High pressure sodium lamps

Fig.7.8 HPS lamp Fig.7.7 250W luminary

The high-pressure sodium discharge lamp is a lamp providing the highest

efficiency in a light source with a good color rendition. Fig.


163

Fig. 7.9 internal construction of HPS

The high-pressure sodium discharge is enclosed in an arc-tube envelope of high

temperature, alkali-vapor resisting high density, polycrystalline alumina.

The difference from the former low-pressure sodium lamp is that the sodium

pressure, with high volume loading, results in a well stabilized discharge and

maximum efficiency.

The high- pressure sodium discharge lamp has an initial efficacy in excess of 100

lumens per watt. Median lamp lifetime is in order of 6000 hours but may be expected

to improve with improved construction techniques.

High efficiency with acceptable color and a small, high brightness source with

low ultraviolet radiation make the high-pressure sodium lamp attractive as a lighting

source for street, roadway and area lighting.

Spectrum of High Pressure Sodium Lamp Spectrum of high pressure sodium lamp. The yellow-red band on the left is the atomic

sodium D-line emission; the turquoise line is a sodium line which is otherwise quite

weak in a low pressure discharge, but become intense in a high pressure discharge.

Most of the other green, blue and violet lines arise from mercury.

Fig. 7.10 spectrum of HPS lamp

7.5.2 Low pressure sodium lamps

Fig. 7.11 LPS of 35W Fig. 7.12 running LPS


164

This type of lamp has special purposes because they give very strong light under

small power. This type of lamps has dark yellow light and is used in tunnels and

closed public places. They also have relatively long life.

7.5.3 Metal halide lamps

This is a very special purpose lamp it has special advantage that it can response

very fast to electric power when turning on and very slow when turning off, i.e. it

turns on quickly and turn off slowly. Thus this type of lamps could be used in medical

operation room and flood lighting. e.g. HSLL-BW-400, 400 watt, 2300 lm/watt.

Metal halide lamps operate under high pressure and temperature, and require

special fixtures to operate safely It gives a bright white light thus it could be used in

illumination of open places such as large stadiums since this type of lamps have

strong glass, they should be put when they should be hanged over large arm poles.

Fig. 7.13 metal halide in stadium Fig. 7.14 metal halide in baseball Stadium

7.5.4 Mercury lamps

There are several types of mercury lamps such as high-pressure, low pressure and

compound mercury lamps. This type has special applications.

Fig. 7.15

A mercury-vapor lamp is a gas discharge lamp that uses mercury in an excited

state to produce light. The arc discharge is generally confined to a small fused quartz

arc tube mounted within a larger borosilicate glass bulb. The outer bulb may be clear

or coated with a phosphor; in either case, the outer bulb provides thermal insulation,

http://en.wikipedia.org/wiki/Halide

http://en.wikipedia.org/wiki/Gas_discharge_lamp

http://en.wikipedia.org/wiki/Mercury_(element)

http://en.wikipedia.org/wiki/Light

http://en.wikipedia.org/wiki/Fused_quartz

http://en.wikipedia.org/wiki/Arc_tube

http://en.wikipedia.org/wiki/Borosilicate_glass

http://en.wikipedia.org/wiki/Phosphor

http://en.wikipedia.org/wiki/Thermal_insulation


165

protection from ultraviolet radiation, and a convenient mounting for the fused quartz

arc tube.

Mercury vapor lamps (and their relatives) are often used because they are relatively

efficient. Phosphor coated bulbs offer better color rendition than either high- or low-

pressure sodium vapor lamps. Mercury vapor lamps also offer a very long lifetime, as

well as intense lighting for several special purpose applications.

7.6 Methods of switching of lamps There are various methods, some of which are:

a) Photo cell

b) Control switch

c) Timer

7.7 Street lighting system The distribution lighting network consists of:

1. Lighting distribution box

2. Poles

3. Lighting luminaries

4. Cables

7.7.1 Lighting distribution box (LDB)

The LDB is a pad-mounted-explosion proof type provided with the following

equipment and devices.

a) One incoming C.B.

b) Four outgoing circuit breakers.

c) One KWH meter

d) Automatic contactor (photocell or timer)

The lighting distribution box is shown in fig 7.16.

Fig 7.16 Lighting Distribution Box

http://en.wikipedia.org/wiki/Ultraviolet

http://en.wikipedia.org/wiki/Lighting_efficiency

http://en.wikipedia.org/wiki/Phosphor

http://en.wikipedia.org/wiki/Color_rendering_index

http://en.wikipedia.org/wiki/Sodium_vapor_lamp


166

7.7.2 Poles

There is a wide range of street lighting poles which can be classified according to

their height (15m, 12m, 10m, 8m, ……3m) or according to their type (stepped,

octagonal, ….., or round).

The poles of 12m height are used in lighting system for most of streets, and the

poles of 3m height are mainly used for gardens lighting. For Alleys and Local streets,

poles of 8 m are used to fulfill the required lighting characteristics.

Fig 7.17 shows the main construction of poles used in street lighting.

(1) Mounting Height (Height above working plane). (2) Overhang. (3) Boom Angle. (4) Boom Length.

Fig 7.17 Construction of street lighting poles

The total pole heights depend on the method of installation. The manufacturer

should increase the pole height by at least 1-5m if it’s directly mounted in soil or in

concrete. Fig 7.18 shows the recommended type of lighting poles (12m high)

Fig 7.18 The 12m high pole used in street lighting


167

The 3m poles are of decorative or round types. This is shown in fig 7.19.

Fig 7.19 The 3m high poles used in gardens

Each pole should be provided with a door opening for cable connection at a height

not less than 80 cm from ground level.

7.7.3 Lighting luminaries

The street lighting designed here to use several types of luminaries. Their type of

lamps is:

250, 400 watt high pressure sodium vapor lamps.

160 watt mercury lamps.

Different shapes of luminaries are shown in fig 7.20.

This type used in our project.

250W HPS street lamp


168

400W HPS street lamp

160W mercury vapor lamp

Fig 7.20 Different shapes of luminaries

7.7.4 Cables

I. Cables of aluminum types should be used to connect the low voltage side of

distribution transformer to the lighting distribution box (LDB), and the cross

sectional area of cables is chosen according to the lighting loads and the rating

of the lighting distribution box (LDB).

II. Types of Aluminum conductors are :

A. ALL Aluminum Alloy Conductor(AAAC)

B. Aluminum Conductor Steel Reinforced(ACSR)

C. Aluminum Alloy Conductor Steel Reinforced(AACSR)

D. Aerially bunched cables(ABC)

III. Available cross section areas of aluminum cables are (4×25) mm2

or

(4×16mm2).

IV. In our project design, the selected cable is AAAC with cross section area in is

(4×25mm2).

V. Cables of 2 mm² copper are used to connect power cables and luminaries.

The following figures show some types of Aluminum Conductors


169

Fig. 7.21 AAAC Fig. 7.22 Abc cables

Fig. 7.23 ACSR for O.H.T.L

7.8 Lighting control and Wiring system 7.8.1 On-off control

Luminaries for dusk to dawn operation will normally be controlled by a

photoelectric cell installed on each luminary, however, central control may be more

economical for luminaries having fixed hours of operation.

An automatic system using a time switch with an astronomical dial or a manual

on-off control will be used for such cases.

7.8.2 Type of system

Multiple wiring systems will be installed, except for extensions to existing series

systems or for long access roads where voltage drops exceeding that permitted for

multiple lighting systems would occur.

Circuits for multiple lighting will be designed to utilize the highest low-voltage

level appropriate for the installation in order to keep wire sizes and voltage drops to a

minimum.

Lamps will be connected phase-to-neutral rather than phase-to-phase. Where

practically, units will be connected to transformers, which serve other loads. Also

protection and disconnection of lighting circuits will be provided.

7.8.3 Grounding

All lighting circuits will include an equipment grounding conductor. The

equipment grounding conductor may be any conductor approved by the NEC, and

will be bonded to the non-current-carrying metal parts of each lighting standard and

luminary.


170

7.9 Design of the street lighting scheme using DIAlux program:

1. We specify the width, we have in our plan.

2. Open red DIALux program

3. Select DIALux wizards

4. Select quick street planning

5. In DIALux street wizard :click next

6. Enter the various street elements and their properties such as

a. Width of side walk

b. Width of bicycle lane

c. Roadway width

d. Number of lanes

7. Enter the various valuation fields for the streets .select a lighting class for

Each valuation field in order to define the photometric requirements of the

Street.

Example:

a) Open lighting class selection: click next

b) Enter the typical speed of the main user type. e.g. Medium(between 30

&60 km/hr)

c) Enter the main user type & the other permitted user types.

d) Enter the main weather type. e.g. dry

e) Enter the type and frequency of the interchanges.

f) Enter the number of vehicles that pass a defined point in a defined

time(determination of traffic flow)

g) Enter whether or not to take a conflict zone into consideration, conflict

zones are zones that are also used by other traffic participants.

h) Enter the complexity of the field of version of the traffic participants

i) Enter the navigational difficulty of the traffic participants.

j) Enter the estimated luminance level of the environment.

e.g. this is a lighting class ME3a

8. Select valuation field for the optimization.

9. Select a luminary for the arrangement from your favorite catalogue

10. Specify which parameters of the luminary arrangement are allowed to vary at

which intervals.

a) Parameters that may be varied for the optimization.

b) Fixed parameters for the optimization.

c) Arrangement type(single sided, staggered or opposite sided)

11. Select suitable distance between luminaries that satisfy required illumination.

SYSTEM GROUNDING

Chapter 8

CHAPTER 8 SYSTEM GROUNDING

171

CHAPTER 8

SYSTEM GROUNDING

8.1.The importance of Earthing

Earthing or grounding is done for safety of equipment and human beings

(including all animals and plants).

In electricity supply systems, an earthing system defines the electrical potential of

theconductors relative to that of the Earth's conductive surface. The choice of earthing

system has implications for the safety and electromagnetic compatibility of the power

supply. Note that regulations for earthing (grounding) systems vary considerably

among different countries.

A protective earth (PE) connection ensures that all exposed conductive surfaces are

at the same electrical potential as the surface of the Earth, to avoid the risk of

electrical shock if a person touches a device in which an insulation fault has occurred.

It ensures that in the case of an insulation fault (a "short circuit"), a very high current

flows, which will trigger an overcurrent protection device (fuse, circuit breaker) that

disconnects the power supply.

A functional earth connection serves a purpose other than providing protection

against electrical shock. In contrast to a protective earth connection, a functional earth

connection may carry a current during the normal operation of a device. Functional

earth connections may be required by devices such as surge suppression and

electromagnetic interference filters, some types of antennas and various measurement

instruments. Generally the protective earth is also used as a functional earth, though

this requires care in some situations.

8.2.Types of earthing

1. Power or System

2. Equipment Safety

The outer housing of electrical equipment is earthed by directly connecting it to a

earth grid or earth electrode, thereby providing a low resistance path to ground. In

case of a fault involving earth the live part of the equipment gets connected with the

low resistance earth path. This produces high earth fault current and the protective

devices in the circuit disconnects the circuit from the power source thereby reducing

further damage to the equipment.

Neutral of electrical equipment are also earthed for equipment safety. Like, neutral

of generators in power plants are earthed through Neutral Grounding Resistor to limit

the earth fault current. Three phase transformer's neutral are earthed to provide neutral

point to supply single phase loads like lighting and small appliances.

http://en.wikipedia.org/wiki/Electricity_supply

http://en.wikipedia.org/wiki/Ground_(electricity)

http://en.wikipedia.org/wiki/Electrical_potential

http://en.wikipedia.org/wiki/Safety

http://en.wikipedia.org/wiki/Electromagnetic_compatibility

http://en.wikipedia.org/wiki/Fuse_(electrical)

http://en.wikipedia.org/wiki/Circuit_breaker

http://en.wikipedia.org/wiki/Electrical_shock

http://en.wikipedia.org/wiki/Surge_suppression

http://en.wikipedia.org/wiki/Electromagnetic_interference

http://en.wikipedia.org/wiki/Antenna_(radio)


172

²

²

²

8.3.safety or protective

Human Safety:

If a person touches an appliance which has an earth fault in it he will not get an

electric shock as his body (standing on the earth) and the equipment's body are at the

same potential provided the equipment is earthed properly. Thus proper earthing

protects a person from getting electric shock.

That's in the design of villas & apartments we had:

Adding the neutral & earth lines at the riser to the 3 phase or even 1 phase

& here is single line diagram of one of the model, added cable specifications.


173

8.4.System Earthing

8.4.1.Earthing requirements

Each electrically separate part of a system, which is magnetically coupled to other

parts at the transformation points, must be separately earthed.

The purpose of earth connections in different parts of a system differs. But

generally one or more of the following is fulfilled:

a) Zero phase-sequence protection. The earth connection must provide a path of

low impedance and adequate thermal capacity for earth fault (zero sequence) current

so that protective relays may operate satisfactorily.

b) Equipment or protective earthing. This is to ensure the safety of the public and

of the personal that operate electrical equipment.

c) Limitation of earth potential differences. This is to avoid injury or death to

persons or to animals that are more susceptible to electric shock than human begins.

d) Lightning and over voltage protection. This conducts to earth charges due to

lightning and protects equipment from over-voltage by means of surge arresters to

which the earth connection is made.

On any transmission or distribution system, these requirements are satisfied by

both system earths and equipment earths. There must also be adequate bonding of the

connections throughout the earthing system to ensure that currents to earth of the

highest magnitude may be carried without fusing of joints or of the earth conductor

itself and without appreciable voltage drop.

8.4.2. Means of earthing

System earthing may be direct, by a connection straight to earth, or indirect with a

resistor or reactor connected in the earth lead. The earth connection is made to the

system neutral (star point) where this exists or, on a true 3-phase system, by

establishing an artificial star point.

The earth wire, when present, not only provides lightning protection but, in the

event of a fault to earth, it provides a path to the nearest system earth for zero phase-

sequence currents additional to that provided by the earth electrodes and the earth

itself.

For outdoor equipment which is manually operated, the best protection which may

be afforded the operator is the provision of an earth-mat, bonded to the equipment at

the point where a man must stand to operate it. In the event of a fault to earth, the

equipment and the earth-mat, has no voltage across the body.


174

8.4.3. neutral systems

8.4.3.1. Insulated neutral system

Under healthy, balanced conditions, the star-point will be at earth potential even

though it is not connected to earth. When a ground fault occurs on one line, as shown.

The fault current is limited by the line to earth capacitances, one of which shorted out

by itself. Thus the fault current (If) is the pharos sum of an alternator stator winding or

transformer secondary winding with unearthed star-point is shown in fig.

8.5.Methods of Earting

DISAVANTAGES ADVANTAGES EXPLAINING TYPE

* The earth fault current

is heavy.

* Earth connections

must be made at

vulnerable point.

* Earth fault should be

isolated due to heavy I

fault.

*The star-point is always

at earth potential so that

when an earth fault occurs

on one line, the potential

difference between

healthy lines & earth can't

exceed max V phase.

*Simple protective

system.

*An arcing ground fault

can't occur.

*Here a direct metallic

connection’s made

from the neutral of

system to one or more

earth electrodes.

*The earth electrodes

may be of plates, rods,

or pipes buried in the

ground.

1. Solid earthing

*Loss of power occurs

in resistance.

*It adds to the cost of

resistor & lightening

arrestors have to be

added.

*It facilitates the use of

discriminative protective

gear.

*It minimizes the hazards

of arcing grounds.

*It improves the system

stability.

*Here heavy ground

current can be reduced

by inserting a current

limiting device

between the neutral of

the system & earth.

*One of the current

limiting devices:

(resistance – metallic

or liquid).

2.Resistive earthing

*It means earthing

through an impedance

(reactive) & ratio of

X0/X1>3

3.Reactance earthing

*By earthing through

Peterson coil the

effect’s to prevent

unbalanced

capacitance currents

entering earth fault.

4. Arc suppression

coil (Paterson coil).


175

8.6.Circuits & equations

EQUATION EQUIVALENT CIRCUIT TYPE

𝐼𝐹𝑎𝑢𝑙𝑡 =3 Vphase

Z1 + Z2 + Z2

1. Solid earthing.

𝑅 =Vline

3 ∗ 𝐼

2. Resistive earthing.

𝐼𝐹𝑎𝑢𝑙𝑡 =Vphase

𝑋𝑐

3. Arc suppression coil

( Peterson coil )


176

8.7.Earth Resistivity & Gradient

It varies widely between different types of soil & is affected by the moisture

content.

Ranges of approximate values for the various types of soil are shown in table

RESISTIVITY (Ω/m) TYPES OF SOIL

10-16 Clay &Loam

80-200 Sandy clay

150-300 Marsh peat

130-500 Sand

Up to 1000 Rock & chalk

8.8.Earth electrodes &networks

8.8.1Hemi sphere

Resistance= 𝜌

2×𝜋×𝑟 .

Resistance = 𝜌

4×𝜋×𝑟 . (for large burial depth)


177

8.8.2. Driven rod

8.8.3. Multi driven electrode.

Where α =(r/s)

8.8.4. Buried plate electrode.

RESISTANCE TYPE

𝑅 = 0.5(1 + 𝛼) 1. Tow rods in parallel

𝑅 =(2 + 𝛼 − 4𝛼2)

6− 7𝛼 2. Three rods in one line

𝑅 =(1 + 2𝛼)

3 3. Three rods in triangle

𝑅 =(12 + 16𝛼 − 21𝛼2)

(48− 40𝛼) 4. Four rods on one line

RESISTANCE TYPE

R =ρ

8r(1 +

𝑟

2.5𝑕 + 𝑟) 1. Normal case

𝑅 =ρ

8r 2. Infinite depth

𝑅 =ρ

4r 3. Zero depth


178

8.5.Burried horizontal wires

𝑅 =𝜌

2𝜋𝐿[𝑙𝑜𝑔𝑒(

𝑙

𝑑) + 𝑓(

𝑕

𝑙)]


179

8.9. measurement of earth electrode resistance & earth loop

impedance

Equation Figure Explain Type

𝑅𝑥 = 0.5(𝑅1 + 𝑅2 + 𝑅3)

*A transformer supplies

current to the electrode

under test via the earth to

an auxiliary one (50m

apart) , h=.618d.,

*There's third electrode in

between, if voltmeter

between aux., third

electrode reach min. that's

proper place.

1. Fall of potential

method

*Suitable for the high

values of electrode

resistance such as tower

footings or single isolated

equipment.

2. The three point

method

𝐼𝑡 ∗ 𝑅𝑡 = 𝐸𝑜

*Measures the series

resistance & an aux.

electrode by means of the

galvanometer 's connected

between the sliding

contact & a second aux.

electrode

3. The ratio method

8.10. Substation earthing:

The requirements for s/s earthing are to dissipate to the earth a large amount

current of the order of thousands of amperes & to control the potential gradient over

the whole s/s area &to avoid Vstep ,Vtouch,Vmech.

𝑅 =𝜌

(1

4𝑟+

1

𝐿) ,

Where:

ρ is average earth resistivity.

r is radius of circular plate.

L is total length of buried conductor.

0.1-0.015 π *(V)over a horizontal distance of 1 m Vstep

𝐸𝑡𝑜𝑢𝑐 𝑕 =(165 + 0.25𝜋)

𝑡

, t =time of clearing fault

0.6-0.8 π

*(V) between a structure earthed to

the mesh &a point on earth surface 1m

away. Vtouch

𝐸𝑚𝑒𝑠𝑕 = 𝑘𝑚𝑘𝑖𝜌𝑙

𝑙

,Km,Ki coefficients

π

*(V) between a structure to a point on

earth at the center of a rectangular

formed by mesh conductors. Vmesh


180

8.11.The high pulse voltage E.S.E. lightening conductor

A lightning rod (AUS) or lightning conductor (UK) is

a metal rod or conductor mounted on top of a building and

electrically connected to the ground through a wire, to

protect the building in the event of lightning. If lightning

strikes the building it will preferentially strike the rod, and

be conducted harmlessly to ground through the wire,

instead of passing through the building, where it could start

a fire or cause electrocution. A lightning rod is a single

component in a lightning protection system. In addition to

rods placed at regular intervals on the highest portions of a

structure, a lightning protection system typically includes a

rooftop network of conductors, multiple conductive paths

from the roof to the ground, bonding connections to

metallic objects within the structure and a grounding

network. The rooftop lightning rod is a metal strip or rod,

usually of copper or aluminum. Lightning protection systems are installed on structures, trees,

monuments, bridges or water vessels to protect from lightning damage. Individual lightning

rods are sometimes called finials, air terminals or strike termination devices & thus we have earthed from the building till the substation.

http://en.wikipedia.org/wiki/Australian_English

http://en.wikipedia.org/wiki/British_English

http://en.wikipedia.org/wiki/Electrical_conductor

http://en.wikipedia.org/wiki/Ground_(electricity)

http://en.wikipedia.org/wiki/Lightning

http://en.wikipedia.org/wiki/Lightning_protection_system

http://en.wikipedia.org/wiki/Lightning

The Shopping Mall

Chapter 9

CHAPTER 9 THE SHOPPING MALL

181

Chapter 9

The Shopping Mall

9.1 Introduction

In this chapter we will lay down the full design of a three story shopping mall

containing 78 outlets and 2 cinema screens to better serve our layout’s population

prosperity and welfare.

The design includes mall lighting details and normal and power socket placement as

well as the detailed wiring scheme and circuit breaker ratings and cable trays

specifications.

The shopping mall is equipped with an emergency backup electrical scheme to avoid

mall blackout and severe under voltage which could harm connected appliances.

During mall black out the emergency lighting will regain function after a limited

time no more than 15 seconds which is the time taken by the emergency generator to

start. The emergency lighting illuminates the mall halls and exit stairs which

facilitates the easy exit of customers and mall personnel.

In the following sections we will show each floor’s lighting calculations and

electrical wiring specifications.

9.2 Ground Floor_

9.2.1_Ground Floor Lighting Calculations_

The lighting calculations are done on basis of 300 lux for stores and 150 lux for hall

ways and stairs. Also a utilization factor of 0.66 and a maintenance factor of 0.8

according to a weekly mall cleaning basis

The used equation is: 𝑁(𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑙𝑎𝑚𝑝𝑠) =𝐸∗𝐴

𝑢∗𝑚∗η


182

Place Lux Area U m efficacy(

η)

number of

lamps

Integer number

of lamps

lamp Power

PF Installe

d wattage

Current

store1 300 116.5 0.66 0.8 35 36.37138 37 52 0.8 1924 10.9318

store2 300 161.2 0.66 0.8 35 50.32517 51 52 0.8 2652 15.0682

Electrical Room 1

300 14.43 0.41 0.6 80 5.499238 8 40 0.8 320 1.81818

store4 300 38.76 0.58 0.8 35 13.76942 14 52 0.8 728 4.13636

store5 300 38.76 0.58 0.8 35 13.76942 14 52 0.8 728 4.13636

store6 300 38.76 0.58 0.8 35 13.76942 14 52 0.8 728 4.13636

store7 300 38.76 0.58 0.8 35 13.76942 14 52 0.8 728 4.13636

store8 300 38.76 0.58 0.8 35 13.76942 14 52 0.8 728 4.13636

store9 300 22.94 0.58 0.8 35 8.149394 8 52 0.8 416 2.36364

store10(bathroom)

300 14.43 0.35 0.8 80 4.831473 8 40 0.8 320 1.81818

store11 300 29.26 0.58 0.8 35 10.39456 10 52 0.8 520 2.95455

store12 300 14.44 0.58 0.8 35 5.129784 6 52 0.8 312 1.77273

store13 300 14.44 0.58 0.8 35 5.129784 6 52 0.8 312 1.77273

store14 300 14.44 0.58 0.8 35 5.129784 6 52 0.8 312 1.77273

store15 300 14.44 0.58 0.8 35 5.129784 6 52 0.8 312 1.77273

store16(bathroom)

300 14.43 0.35 0.8 80 4.831473 8 40 0.8 320 1.81818

Electrical Room 2

300 43.64 0.6 0.6 80 11.36458 12 40 0.8 480 2.72727

store18 300 33.07 0.58 0.8 35 11.74628 12 52 0.8 624 3.54545

store19 300 17 0.58 0.8 35 6.039219 6 52 0.8 312 1.77273

store20 300 33.07 0.58 0.8 35 11.74628 12 52 0.8 624 3.54545

store21 300 17 0.58 0.8 35 6.039219 6 52 0.8 312 1.77273

store22 300 20.83 0.58 0.8 35 7.398044 8 52 0.8 416 2.36364

store23 300 48.46 0.58 0.8 35 17.21533 16 52 0.8 832 4.72727

store24 300 116.5 0.66 0.8 35 36.37138 37 52 0.8 1924 10.9318

store25 300 46.01 0.58 0.8 35 16.34319 19 52 0.8 988 5.61364

store26 300 27.74 0.58 0.8 35 9.854585 10 52 0.8 520 2.95455

store27 300 27.74 0.58 0.8 35 9.854585 10 52 0.8 520 2.95455

store28 300 46.01 0.58 0.8 35 16.34319 19 52 0.8 988 5.61364

store29 300 46.01 0.58 0.8 35 16.34319 19 52 0.8 988 5.61364

store30 300 27.74 0.58 0.8 35 9.854585 10 52 0.8 520 2.95455

store31 300 27.74 0.58 0.8 35 9.854585 10 52 0.8 520 2.95455

store32 300 46.01 0.58 0.8 35 16.34319 19 52 0.8 988 5.61364

coridoor1 150 108 0.64 0.8 35 34.77243 31 26 0.8 806 4.57955

coridoor2 150 99.84 0.64 0.8 35 32.14286 28 26 0.8 728 4.13636

coridoor3 150 211 0.64 0.8 35 67.93012 68 26 0.8 1768 10.0455

coridoor4 150 59.45 0.64 0.8 35 19.13987 20 26 0.8 520 2.95455

coridoor5 150 61.22 0.64 0.8 35 19.71004 20 26 0.8 520 2.95455

coridoor6 150 50.13 0.64 0.8 35 16.1402 16 26 0.8 416 2.36364

coridoor7 150 83.74 0.64 0.8 35 26.95828 27 26 0.8 702 3.98864

coridoor8 150 83.74 0.64 0.8 35 26.95956 27 26 0.8 702 3.98864

stairs1 150 58.8 0.41 0.6 80 22.40854 24 20 0.8 480 2.72727

stairs2 150 81.6 0.41 0.6 80 31.09756 32 20 0.8 640 3.63636

stairs3 150 91 0.41 0.6 80 34.67988 36 20 0.8 720 4.09091

outdoor lighting

_ _ _ _ _ _ 17 70 1 1190 5.40909


183


184

9.2.2 Ground Floor Socket Calculations & Wiring_

Room Main

currents

line numb

er

line type

current MCB

Light Line C.S.A

line numb

er line type

number of socke

ts

Current

MCB

Socket Lines C.S.A

shop 1 42.01181

818

1 Lightin

g 1 5.465909

091 10

2*2.5 mm2

3 normal

sockets 1 7 4.4 10

3x2.5mm2

2 Lightin

g 2 5.465909

091 10

2*2.5 mm2

4 power

sockets 1 1 20 25

3x4mm2

5 power

sockets 2 1 20 25

3x4mm2

shop 2 44.76939

394

1 Lightin

g 1 3.643939

394 10

2*2.5 mm2

4 normal

sockets 1 7 4.4 10

3x2.5mm2

2 Lightin

g 2 5.022727

273 10

2*2.5 mm2

5 power

sockets 1 1 20 25

3x4mm2

3 Lightin

g 3 5.022727

273 10

2*2.5 mm2

6 power

sockets 2 1 20 25

3x4mm2

Electrical Room 1

4.618181818

1 Lightin

g 1 1.818181

818 10

2*2.5 mm2

2 normal

sockets 1 3 2.8 10

3x2.5mm2

shop 4 8.536363

636 1

Lighting 1

4.136363636

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 5 8.536363

636 1

Lighting 1

4.136363636

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 6 8.536363

636 1

Lighting 1

4.136363636

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 7 8.536363

636 1

Lighting 1

4.136363636

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 8 8.536363

636 1

Lighting 1

4.136363636

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 9 6.363636

364 1

Lighting 1

2.363636364

10 2*2.5 mm2

2 normal

sockets 1 6 4 10

3x2.5mm2

Bathroom 1 20.99818

182

1 Lightin

g 1 1.818181

818 10

2*2.5 mm2

2 normal

sockets 1 2 2.4 10

3x2.5mm2

3 power

sockets 1 1 25 32

3*6 mm2

shop 11 7.354545

455 1

Lighting 1

2.954545455

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 12 4.972727

273 1

Lighting 1

1.772727273

10 2*2.5 mm2

2 normal

sockets 1 4 3.2 10

3x2.5mm2

shop 13 4.972727

273 1

Lighting 1

1.772727273

10 2*2.5 mm2

2 normal

sockets 1 4 3.2 10

3x2.5mm2

shop 14 4.972727

273 1

Lighting 1

1.772727273

10 2*2.5 mm2

2 normal

sockets 1 4 3.2 10

3x2.5mm2

shop 15 4.972727

273 1

Lighting 1

1.772727273

10 2*2.5 mm2

2 normal

sockets 1 4 3.2 10

3x2.5mm2

Bathroom 2 4.218181

818 1

Lighting 1

1.818181818

10 2*2.5 mm2

2 normal

sockets 1 2 2.4 10

3x2.5mm2

Electrical Room 2

5.927272727

1 Lightin

g 1 2.727272

727 10

2*2.5 mm2

2 normal

sockets 1 4 3.2 10

3x2.5mm2

shop 18 7.945454

545 1

Lighting 1

3.545454545

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 19 4.972727

273 1

Lighting 1

1.772727273

10 2*2.5 mm2

2 normal

sockets 1 4 3.2 10

3x2.5mm2

shop 20 7.945454

545 1

Lighting 1

3.545454545

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 21 4.972727

273 1

Lighting 1

1.772727273

10 2*2.5 mm2

2 normal

sockets 1 4 3.2 10

3x2.5mm2

shop 22 5.963636

364 1

Lighting 1

2.363636364

10 2*2.5 mm2

2 normal

sockets 1 5 3.6 10

3x2.5mm2


185

shop 23 9.127272

727 1

Lighting 1

4.727272727

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 24 38.90954

545

1 Lightin

g 1 2.363636

364 10

2*2.5 mm2

3 normal

sockets 1 7 4.4 10

3x2.5mm2

2 Lightin

g 2 5.465909

091 10

2*2.5 mm2

4 power

sockets 1 1 20 25

3x4mm2

5 power

sockets 2 1 20 25

3x4mm2

shop 25 10.01363

636 1

Lighting 1

5.613636364

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 26 7.354545

455 1

Lighting 1

2.954545455

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 27 7.354545

455 1

Lighting 1

2.954545455

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 28 10.01363

636 1

Lighting 1

5.613636364

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 29 10.01363

636 1

Lighting 1

5.613636364

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 30 7.354545

455 1

Lighting 1

2.954545455

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

shop 31 7.354545

455 1

Lighting 1

2.954545455

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5cm2

shop 32 10.01363

636 1

Lighting 1

5.613636364

10 2*2.5 mm2

2 normal

sockets 1 7 4.4 10

3x2.5mm2

corridor 1

2.289772727

1 Lightin

g 1 2.289772

727 10

2*2.5 mm2

2.289772727

2 Lightin

g 2 2.289772

727 10

2*2.5 mm2

corridor 2

2.068 1 Lightin

g 1 2.068 10

2*2.5 mm2

2.068 2 Lightin

g 2 2.068 10

2*2.5 mm2

corridor 3

5 1 Lightin

g 1 5 10

2*2.5 mm2

5 2 Lightin

g 2 5 10

2*2.5 mm2

corridor 4

1.475 1 Lightin

g 1 1.475 10

2*2.5 mm2

1.475 2 Lightin

g 2 1.475 10

2*2.5 mm2

corridor 5

1.475 1 Lightin

g 1 1.475 10

2*2.5 mm2

1.475 2 Lightin

g 2 1.475 10

2*2.5 mm2

corridor 6

1.18 1 Lightin

g 1 1.18 10

2*2.5 mm2

1.18 2 Lightin

g 2 1.18 10

2*2.5 mm2

corridor 7

1.994 1 Lightin

g 1 1.994 10

2*2.5 mm2

1.994 2 Lightin

g 2 1.994 10

2*2.5 mm2

corridor 8

1.994 1 Lightin

g 1 1.994 10

2*2.5 mm2

1.994 2 Lightin

g 2 1.994 10

2*2.5 mm2

stairs 1 2.727272

727 1

Lighting 1

1.36364 10 2*2.5 mm2

stairs 2 3.636363

636 1

Lighting 1

1.36364 10 2*2.5 mm2


186

stairs 3 4.090909

091 1

Lighting 1

1.36364 10 2*2.5 mm2

outdoor lighting

5.409090909

1 Lightin

g 1 5.409090

909 10

2*2.5 mm2

Water pump 1

20 1 Power Line 1 20 25 2x4mm

2

Water pump 2

20 1 Power Line 1 20 25 2x4mm

2

Escalator 1 30.303 1 Power Line 1 30.30

3 40

2x10mm2

Escalator 2 30.303 1 Power Line 1 30.30

3 40

2x10mm2

9.2.3 Ground Floor Local Feeders_

line Room Main currents MCB Rating

C.S.A (1ph+n+e)

m1 shop 1 42 63 3x16mm2

m2 shop 2 44.7 63 3x16mm2

m4 shop 4 8.536363636 16 3x3mm2

m5 shop 5 8.536363636 16 3x3mm2

m6 shop 6 8.536363636 16 3x3mm2

m7 shop 7 8.536363636 16 3x3mm2

m8 shop 8 8.536363636 16 3x3mm2

m9 shop 9 6.363636364 16 3x3mm2

m11 shop 11 7.354545455 16 3x3mm2

m12 shop 12 4.972727273 10 3x2.5mm2

m13 shop 13 4.972727273 10 3x2.5mm2

m14 shop 14 4.972727273 10 3x2.5mm2

m15 shop 15 4.972727273 10 3x2.5mm2

m18 shop 18 7.945454545 16 3x3mm2

m19 shop 19 4.972727273 10 3x2.5mm2

m20 shop 20 7.945454545 16 3x3mm2

m21 shop 21 4.972727273 10 3x2.5mm2

m22 shop 22 5.963636364 10 3x2.5mm2

m23 shop 23 9.127272727 16 3x3mm2

m24 shop 24 38.9 63 3x16mm2

m25 shop 25 10.01363636 16 3x3mm2

m26 shop 26 7.354545455 16 3x3mm2

m27 shop 27 7.354545455 16 3x3mm2

m28 shop 28 10.01363636 16 3x3mm2


187

m29 shop 29 10.01363636 16 3x3mm2

m30 shop 30 7.354545455 16 3x3mm2

m31 shop 31 7.354545455 16 3x3mm2

m32 shop 32 10.01363636 16 3x3mm2

m3 Electrical Room 1 4.618181818 10 3x2.5mm2

m17 Electrical Room 2 5.927272727 10 3x2.5mm2

m10 Bathroom 1 20.99818182 32 3x6mm2

m16 Bathroom 2 4.218181818 10 3x2.5mm2

m33 corridor 1

2.289772727 10 2x2.5mm2

m34 2.289772727 10 2x2.5mm2

m35 corridor 2

2.068 10 2x2.5mm2

m36 2.068 10 2x2.5mm2

m37 corridor 3

5 10 2x2.5mm2

m38 5 10 2x2.5mm2

m39 corridor 4

1.475 10 2x2.5mm2

m40 1.475 10 2x2.5mm2

m41 corridor 5

1.475 10 2x2.5mm2

m42 1.475 10 2x2.5mm2

m43 corridor 6

1.18 10 2x2.5mm2

m44 1.18 10 2x2.5mm2

m45 corridor 7

1.994 10 2x2.5mm2

m46 1.994 10 2x2.5mm2

m47 corridor 8

1.994 10 2x2.5mm2

m48 1.994 10 2x2.5mm2

m49 stairs 1 2.727272727 10 2x2.5mm2

m50 stairs 2 3.636363636 10 2x2.5mm2

m51 stairs 3 4.090909091 10 2x2.5mm2

m52 outdoor lighting 5.409090909 10 2x2.5mm2

m53 Water pump 1 20 25 2x4mm2

m54 Water pump 2 20 25 2x4mm2

m55 Escalator 1 30.303 40 2x10mm2

m56 Escalator 2 30.303 40 2x10mm2


188

9.2.4 Ground Floor SMDBs_& Cable Tray Dimension

It should be noted that each floor contains 2 electrical rooms, the first electrical

room consists of one service panel board "SMDB-G1" where the G indicates that this

panel board is in the ground floor and the numeral 1 indicates that this service panel is

located in the electrical room 1.The first electrical room also contains an emergency

panel board "EMDB-G". The second electrical room consists of only one service

panel "SMDB-G2". The service and emergency panel's enclosures are compliant with

the standards "service enclosure Ip40 (NEMA1)"

line Room Main currents

MCB Ratin

g

C.S.A (1ph+n+e)

Local Panel Code

Service Panel Main

current (per

phase)

Service Panel 3ph

MCCB Rating

Service Panel Incoming Cable

(3ph+n+e)

Cable Overall

Diameter

Cable Tray Width (mm)

Installed Cable Tray Width (cm)

E L E C T R I C A L

R O O M

1

S M D B - G 1

m1 store 1 42 63 3x16m

m2 LPP-G1-1

90.199091

100 (3x35+16+1

6)mm2

6.8

554.4

60

m2 store 2 44.7 63 3x16m

m2 LPP-G1-2

6.8

m4 store 4 8.5363636

36 16

3x3mm2

LPP-G1-4

3.8

m5 store 5 8.5363636

36 16

3x3mm2

LPP-G1-5

3.8

m6 store 6 8.5363636

36 16

3x3mm2

LPP-G1-6

3.8

m7 store 7 8.5363636

36 16

3x3mm2

LPP-G1-7

3.8

m8 store 8 8.5363636

36 16

3x3mm2

LPP-G1-8

3.8

m9 store 9 6.3636363

64 16

3x3mm2

LPP-G1-9

3.8

m11 store 11 7.3545454

55 16

3x3mm2

LPP-G1-11

3.8

m12 store 12 4.9727272

73 10

3x2.5mm2

LPP-G1-12

3.6

m25 store 25 10.013636

36 16

3x3mm2

LPP-G1-25

3.8

m26 store 26 7.3545454

55 16

3x3mm2

LPP-G1-26

3.8

m27 store 27 7.3545454

55 16

3x3mm2

LPP-G1-27

3.8

m28 store 28 10.013636

36 16

3x3mm2

LPP-G1-28

3.8


189

m3 Electric

al Room 1

4.618181818

10 3x2.5m

m2 LPP-G1-3

3.6

m10 Bathroo

m 1 20.998181

82 32

3x6mm2

LPP-G1-10

5

m33 corridor

1 2.8068181

82 10

2x2.5mm2

3.6

m35 corridor

2 2.068 10

2x2.5mm2

3.6

m37 corridor

3 5 10

2x2.5mm2

3.6

m45 corridor

7 1.994 10

2x2.5mm2

3.6

m53 Water

pump 1 20 25

2x4mm2

4.6

m55 Escalat

or 1 30.303 40

2x10mm2

5.8

E L E C T R I C A L

R O O M

2

S M D B - G 2

m13 store 13 4.9727272

73 10

3x2.5mm2

LPP-G2-13

67.154455

80 (3x25+16+1

6)mm2

3.6

543.6

60

m14 store 14 4.9727272

73 10

3x2.5mm2

LPP-G2-14

3.6

m15 store 15 4.9727272

73 10

3x2.5mm2

LPP-G2-15

3.6

m18 store 18 7.9454545

45 16

3x3mm2

LPP-G2-18

3.8

m19 store 19 4.9727272

73 10

3x2.5mm2

LPP-G2-19

3.6

m20 store 20 7.9454545

45 16

3x3mm2

LPP-G2-20

3.8

m21 store 21 4.9727272

73 10

3x2.5mm2

LPP-G2-21

3.6

m22 store 22 5.9636363

64 10

3x2.5mm2

LPP-G2-22

3.6

m23 store 23 9.1272727

27 16

3x3mm2

LPP-G2-23

3.8

m24 store 24 38.9 63 3x16m

m2

LPP-G2-24

6.8

m29 store 29 10.013636

36 16

3x3mm2

LPP-G2-29

3.8

m30 store 30 7.3545454

55 16

3x3mm2

LPP-G2-30

3.8

m31 store 31 7.3545454

55 16

3x3mm2

LPP-G2-31

3.8

m32 store 32 10.013636

36 16

3x3mm2

LPP-G2-32

3.8


190

m16 Bathroo

m 2 4.2181818

18 10

3x2.5mm2

LPP-G2-16

3.6

m17 Electric

al Room 2

5.927272727

10 3x2.5m

m2

LPP-G2-17

3.6

m39 corridor

4 1.475 10

2x2.5mm2

3.6

m41 corridor

5 1.475 10

2x2.5mm2

3.6

m43 corridor

6 1.18 10

2x2.5mm2

3.6

m47 corridor

8 1.994 10

2x2.5mm2

3.6

m52 outdoor lightnin

g

5.409090909

10 2x2.5m

m2

3.6

m54 Water

pump 2 20 25

2x4mm2

4.6

m56 Escalat

or 2 30.303 40

2x10mm2

5.8


191

9.2.5 Ground Floor Emergency Backup Scheme_

The shopping mall is equipped with an emergency backup electrical scheme to avoid

mall blackout and severe under voltage which could harm connected appliances.

During mall black out the emergency lighting will regain function after a limited

time no more than 15 seconds which is the time taken by the emergency generator to

start. The emergency lighting illuminates the mall halls and exit stairs which

facilitates the easy exit of customers and mall personnel.

The following table shows the emergency panel connected loads which mainly

include 50% of Hall way lighting providing illumination of 75 lux since the mall

shops are not equipped with a backup lighting plan, so this percentage of hallway

lighting will provide enough illumination to assure both customer and personnel

safety.

Emergency Panel (Lighting :75 lux) EMDB-G

Place Line Line current MCB Rating

C.S.A Main Panel

Current Main MCB

Main CSA

Corridor 1 m34e 2.806818182 10 2x2.5mm2

36.59736364 40A 2x10mm2

Corridor 2 m36e 2.068 10 2x2.5mm2

Corridor 3 m38e 5 10 2x2.5mm2

Corridor 4 m40e 1.475 10 2x2.5mm2

Corridor 5 m42e 1.475 10 2x2.5mm2

Corridor 6 m44e 1.18 10 2x2.5mm2

Corridor 7 m46e 1.994 10 2x2.5mm2

Corridor 8 m48e 1.994 10 2x2.5mm2

Bathroom 1 m57e 1.81 10 2x2.5mm2

Bathroom 2 m58e 1.81 10 2x2.5mm2

Electrical Room 1 m59e 1.81 10 2x2.5mm2

Electrical Room 2 m60e 2.72 10 2x2.5mm2

stairs 1 m48e 2.727272727 10 2x2.5mm2

stairs 2 m50e 3.636363636 10 2x2.5mm2

stairs 3 m51e 4.090909091 10 2x2.5mm2


192


193

9.3 First Floor_

9.3.1 First Floor Lighting Calculations_





𝑢∗𝑚∗η

P L A C E

L U X

A R E A

u m η No. of

Lamps

Int. No. of Locations

Lamp

Wattage

PF

Installed

Wattage

Light Line

Current

Light Line 1

Light Line 2

C.B of Line 1

C.B of Line 2

Light Line 1 CSA

Light Line 2 CSA

Store 1

300

78.29

0.66

0.8

35

24.4410277

24 52 0.8

1248 7.09090

9091 3.54545455

3.545454545

10 10 2.5 2.5

Store 2

300

78.29

0.66

0.8

35

24.4410277

24 52 0.8

1248 7.09090

9091 3.54545455

3.545454545

10 10 2.5 2.5

Store 3

300

82.79

0.66

0.8

35

25.846029

25 52 0.8

1300 7.38636

3636 3.69318182

3.693181818

10 10 2.5 2.5

Store 4

300

28.564

0.66

0.8

35

8.91733267

8 52 0.8

416 2.36363

6364 2.36363636

_ 10 _ 2.5 _

Store 5

300

14.171

0.66

0.8

35

4.42401349

5 52 0.8

260 1.47727

2727 1.47727273

_ 10 _ 2.5 _

Store 6

300

14.171

0.66

0.8

35

4.42401349

5 52 0.8

260 1.47727

2727 1.47727273

_ 10 _ 2.5 _

Store 7

300

14.171

0.66

0.8

35

4.42401349

5 52 0.8

260 1.47727

2727 1.47727273

_ 10 _ 2.5 _

Store 8

300

14.171

0.66

0.8

35

4.42401349

5 52 0.8

260 1.47727

2727 1.47727273

_ 10 _ 2.5 _

Store 9

300

43.62

0.66

0.8

35

13.6176324

14 52 0.8

728 4.13636

3636 4.13636364

_ 10 _ 2.5 _

Store 10

300

33.108

0.66

0.8

35

10.335758

10 52 0.8

520 2.95454

5455 2.95454545

_ 10 _ 2.5 _

Store 11

300

16.278

0.66

0.8

35

5.08163711

6 52 0.8

312 1.77272

7273 1.77272727

_ 10 _ 2.5 _

Store 12

300

33.108

0.66

0.8

35

10.335758

10 52 0.8

520 2.95454

5455 2.95454545

_ 10 _ 2.5 _

Store 13

300

16.278

0.66

0.8

35

5.08163711

6 52 0.8

312 1.77272

7273 1.77272727

_ 10 _ 2.5 _

Store 14

300

21.293

0.66

0.8

35

6.64725899

7 52 0.8

364 2.06818

1818 2.06818182

_ 10 _ 2.5 _

Store 15

300

47.767

0.66

0.8

35

14.9121816

16 52 0.8

832 4.72727

2727 4.72727273

_ 10 _ 2.5 _

Store 16

300

120.9

0.66

0.8

35

37.7438811

38 52 0.8

1976 11.2272

7273 5.61363636

5.613636364

10 10 2.5 2.5

Store 17

300

121.02

0.66

0.8

35

37.7803134

38 52 0.8

1976 11.2272

7273 5.61363636

5.613636364

10 10 2.5 2.5

Store 18

300

166.23

0.66

0.8

35

51.8953234

52 52 0.8

2704 15.3636

3636 7.68181818

7.681818182

10 10 2.5 2.5

Store 19

300

16.107

0.66

0.8

35

5.02840909

6 52 0.8

312 1.77272

7273 1.77272727

_ 10 _ 2.5 _

Store 20

300

46.7 0.66

0.8

35

14.5791708

15 52 0.8

780 4.43181

8182 4.43181818

_ 10 _ 2.5 _

Store 21

300

58.347

0.66

0.8

35

18.2152535

19 52 0.8

988 5.61363

6364 5.61363636

_ 10 _ 2.5 _

Store 22

300

46.7 0.66

0.8

35

14.5791708

15 52 0.8

780 4.43181

8182 4.43181818

_ 10 _ 2.5 _

Store 23

300

46.7 0.66

0.8

35

14.5791708

15 52 0.8

780 4.43181

8182 4.43181818

_ 10 _ 2.5 _

Store 24

300

28.462

0.66

0.8

35

8.88548951

9 52 0.8

468 2.65909

0909 2.65909091

_ 10 _ 2.5 _


194

Store 25

300

28.462

0.66

0.8

35

8.88548951

9 52 0.8

468 2.65909

0909 2.65909091

_ 10 _ 2.5 _

Store 26

300

46.7 0.66

0.8

35

14.5791708

15 52 0.8

780 4.43181

8182 4.43181818

_ 10 _ 2.5 _

Hall 1

150

80.52

0.64

0.8

35

25.9229052

18 26 0.8

468 2.65909

0909 1.32954545

1.329545455

10 10 2.5 2.5

Hall 2

150

198.18

0.64

0.8

35

63.8027988

48 26 0.8

1248 7.09090

9091 3.5 3.5 10 10 2.5 2.5

Hall 3 150

83.571

0.64

0.8

35

26.9051554

20 26 0.8

520 2.95454

5455 1.47727273

1.477272727

10 10 2.5 2.5

Hall 4 150

58.8 0.64

0.8

35

18.9302885

22 26 0.8

572 3.25 1.625 1.625 10 10 2.5 2.5

Hall 5 150

114.38

0.66

0.8

35

35.708042

28 26 0.8

728 4.13636

3636 2.06818182

2.068181818

10 10 2.5 2.5

Hall 6 150

54.108

0.64

0.8

35

17.4196321

20 26 0.8

520 2.95454

5455 1.47727273

1.477272727

10 10 2.5 2.5

Hall 7 150

33.891

0.64

0.8

35

10.9109289

9 26 0.8

234 1.32954

5455 1.32954545

_ 10 10 2.5 2.5

Hall 8 150

74.227

0.64

0.8

35

23.8969136

22 26 0.8

572 3.25 1.625 1.625 10 10 2.5 2.5

Hall 9 150

74.227

0.64

0.8

35

23.8969136

20 26 0.8

520 2.95454

5455 1.47727273

1.477272727

10 10 2.5 2.5

WC1 300

14.438

0.35

0.8

80

4.83428571

5 40 0.8

200 1.13636

3636 1.13636364

_ 10 _ 2.5 _

WC2 300

14.438

0.35

0.8

80

4.83428571

5 40 0.8

200 1.13636

3636 1.13636364

_ 10 _ 2.5 _

Entrance

300

115.88

36 70 0.7

2520 16.3636

3636 8.18 8.18 10 10 2.5 2.5


195


196

9.3.2 First Floor Socket Calculations & Wiring_

L I N E

R O O M

Store Main

Current

LINE number

Line Type

C U R R E N T

C B

C.S.A (1phase+neut

ral) mm

2

Line No.

T Y P E

Number Of Sockets

C U R R E N T

C B

C.S.A (1phase+neutral+earth)m

m2

m1 Shop1 38.08

L1 LIGHTING

3.5 10

2x2.5 L3 N.S 7 4.4 10

3x2.5

L2 LIGHTING

3.5 10

2x2.5 L4 P.S 1 20 25

3x4

L5 P.S 1 20 25

3x4

m2 Shop2 38.08

L1 LIGHTING

3.5 10

2x2.5 L3 N.S 7 4.4 10

3x2.5

L2 LIGHTING

3.5 10

2x2.5 L4 P.S 1 20 25

3x4

L5 P.S 1 20 25

3x4

m3 Shop3 38.38

L1 LIGHTING

3.8 10

2x2.5 L3 N.S 7 4.4 10

3x2.5

L2 LIGHTING

3.5 10

2x2.5 L4 P.S 1 20 25

3x4

L5 P.S 1 20 25

3x4

m4 Shop4 5.48 L1 LIGHTING

2.4 10

2x2.5 L2 N.S 7 4.4 10

3x2.5


1.47 10

2x2.5 L2 N.S 4 3.2 10

3x2.5


1.47 10

2x2.5 L2 N.S 4 3.2 10

3x2.5


1.47 10

2x2.5 L2 N.S 4 3.2 10

3x2.5


1.47 10

2x2.5 L2 N.S 4 3.2 10

3x2.5

m9 Electrical room 2

6.34 L1 LIGHTING

4.1 10

2x2.5 L2 N.S 4 3.2 16

3x3


2.95 10

2x2.5 L2 N.S 4 3.2 10

3x2.5


1.7 10

2x2.5 L2 N.S 4 3.2 10

3x2.5


2.95 10

2x2.5 L2 N.S 4 3.2 10

3x2.5


1.7 10

2x2.5 L2 N.S 4 3.2 10

3x2.5


2.07 10

2x2.5 L2 N.S 5 3.6 10

3x2.5


4.73 10

2x2.5 L2 N.S 7 4.4 10

3x2.5

m16 Shop16 42.28

L1 LIGHTING

5.6 10

2x2.5 L3 N.S 7 4.4 10

3x2.5

L2 LIGHTING

5.6 10

2x2.5 L4 P.S 1 20 25

3x4

L5 P.S 1 20 25

3x4

m17 Shop17 42.28

L1 LIGHTING

5.6 10

2x2.5 L3 N.S 7 4.4 10

3x2.5

L2 LIGHTING

5.6 10

2x2.5 L4 P.S 1 20 25

3x4


197

L5 P.S 1 20 25

3x4

m18 shop18 46.48

L1 LIGHTING

7.7 10

2x2.5 L3 N.S 7 4.4 10

3x2.5

L2 LIGHTING

7.7 10

2x2.5 L4 P.S 1 20 25

3x4

L5 P.S 1 20 25

3x4


3.76 L1 LIGHTING

1.8 10

2x2.5 L2 N.S 3 2.8 16

3x3

m20 shop20 7.48 L1 LIGHTING

4.4 10

2x2.5 L2 N.S 7 4.4 10

3x2.5


5.6 10

2x2.5 L2 N.S 7 4.4 10

3x2.5


4.4 10

2x2.5 L2 N.S 7 4.4 10

3x2.5


4.4 10

2x2.5 L2 N.S 7 4.4 10

3x2.5


2.65 10

2x2.5 L2 N.S 7 4.4 10

3x2.5


2.65 10

2x2.5 L2 N.S 7 4.4 10

3x2.5


4.4 10

2x2.5 L2 N.S 7 4.4 10

3x2.5

m27 Bathroo

m 1 20.58

L1 LIGHTING

1.4 10

2x2.5 L2 N.S 2 2.4 10

3x2.5

L3 P.S 1 25 32

3x6

m28

Bathroom 2

20.58

L1 LIGHTING

1.4 10

2x2.5 L2 N.S 2 2.4 10

3x2.5

L3 P.S 1 25

32

3x6

m29

HALL1

1.33 L29 LIGHTING

1.33 10

2x2.5

m30 1.33 L30 LIGHTING

1.33 10

2x2.5

m31

HALL2

3.5045 L31 LIGHTING

3.5045

10

2x2.5


3.5045

10

2x2.5

m33

HALL3

1.48 L33 LIGHTING

1.47727

3

10

2x2.5


1.47727

3

10

2x2.5

m35

HALL4

1.625 L35 LIGHTING

1.625

10

2x2.5


1.625

10

2x2.5

m37

HALL5

2 L37 LIGHTING

2.06818

2

10

2x2.5

m38 2 L38 LIGHTING

2.06818

2

10

2x2.5

m39

HALL6

1.48 L39 LIGHTING

1.47727

3

10

2x2.5


1.47727

3

10

2x2.5

m41 HALL7 1.33 L41 LIGHTING

1.32954

10

2x2.5


198

5

m42

HALL8

1.625 L42 LIGHTING

1.625

10

2x2.5


1.625

10

2x2.5

m44

HALL9

1.48 L44 LIGHTING

1.47727

3

10

2x2.5


1.47727

3

10

2x2.5

m46

Entrance

8.18 L46 LIGHTING

8.18 10

2x2.5


8.18 10

2x2.5

m48 Escalato

r 3 30.303 1

Power

Line 1

30.303

40

3x10mm2

m49 Escalato

r 4 30.303 1

Power

Line 1

30.303

40

3x10mm2

9.3.3 First Floor Local Feeders

Line Room Main

Current MCB Rating C.S.A (1ph+n+e)

m1 Store 1 38.08 40 3x6mm2

m2 Store 2 38.08 40 3x6mm2

m3 Store 3 38.38 40 3x6mm2

m4 Store 4 5.48 10 3x2.5mm2

m5 Store 5 3.71 10 3x2.5mm2

m6 Store 6 3.71 10 3x2.5mm2

m7 Store 7 3.71 10 3x2.5mm2

m8 Store 8 3.71 10 3x2.5mm2

m10 Store 10 5.19 10 3x2.5mm2

m11 Store 11 3.94 10 3x2.5mm2

m12 Store 12 5.19 10 3x2.5mm2

m13 Store 13 3.94 10 3x2.5mm2

m14 Store 14 4.59 10 3x2.5mm2

m15 Store 15 7.81 10 3x2.5mm2

m16 Store 16 42.28 63 3x16mm2

m17 Store 17 42.28 63 3x16mm2

m18 Store 18 46.48 63 3x16mm2

m20 Store 20 7.48 10 3x2.5mm2

m21 Store 21 8.68 10 3x2.5mm2

m22 Store 22 7.48 10 3x2.5mm2


199

m23 Store 23 7.48 10 3x2.5mm2

m24 Store 24 5.73 10 3x2.5mm2

m25 Store 25 5.73 10 3x2.5mm2

m26 Store 26 7.48 10 3x2.5mm2


3.76 10 3x2.5mm2


6.34 10 3x2.5mm2

m27 Bathroom

1 20.58 25 3x4mm2

m28 Bathroom

2 20.58 25 3x4mm2

m29 HALL1

1.33 10 2x2.5mm2

m30 1.33 10 2x2.5mm2

m31 HALL2

3.045 10 2x2.5mm2

m32 3.045 10 2x2.5mm2

m33 HALL3

1.48 10 2x2.5mm2

m34 1.48 10 2x2.5mm2

m35 HALL4

1.625 10 2x2.5mm2

m36 1.625 10 2x2.5mm2

m37 HALL5

2 10 2x2.5mm2

m38 2 10 2x2.5mm2

m39 HALL6

1.48 10 2x2.5mm2

m40 1.48 10 2x2.5mm2

m41 HALL7 1.33 10 2x2.5mm2

m42 HALL8

1.625 10 2x2.5mm2

m43 1.625 10 2x2.5mm2

m44 HALL9

1.48 10 2x2.5mm2

m45 1.48 10 2x2.5mm2

m46 Entrance

8.18 10 2x2.5mm2

m47 8.18 10 2x2.5mm2

m48 Escalator 3 30.303 40 2x10mm2

m49 Escalator 4 30.303 40 2x10mm2


200

9.3.4 First Floor SMDBs_& Cable Tray Dimension_


room consists of one service panel board "SMDB-F1" where the F indicates that this

panel board is in the First floor and the numeral 1 indicates that this service panel is


panel board "EMDB-F". The second electrical room consists of only one service panel

"SMDB-F2". The service and emergency panel's enclosures are compliant with the

standards "service enclosure Ip40 (NEMA1)"

line Room Main

currents

MCB

Rating

C.S.A (1ph+n+e)

Local Panel Code

Service Panel Main

current (per

phase)

Service Panel 3ph

MCCB Rating


(3ph+n+e)

Cable Overall Diamet

er

Cable Tray

Width (mm)

Installed Cable Tray

Width (cm)

E L E C T R I C A L

R O O M

1

S M D B - F 1

m1 Store 1 38.08 40 3x6mm2 LPP-F1-1

106.2026667

160A (3x70+35+35)

mm2

5

536.4

60

m2 Store 2 38.08 40 3x6mm2 LPP-F1-2

5

m3 Store 3 38.38 40 3x6mm2 LPP-F1-3

5

m4 Store 4 5.48 10 3x2.5m

m2 LPP-F1-4

3.6

m5 Store 5 3.71 10 3x2.5m

m2 LPP-F1-5

3.6

m6 Store 6 3.71 10 3x2.5m

m2 LPP-F1-6

3.6

m17 Store 17 42.28 63 3x16mm

2 LPP-F1-17

6.8

m18 Store 18 46.48 63 3x16mm

2 LPP-F1-18

6.8

m20 Store 20 7.48 10 3x2.5m

m2 LPP-F1-20

3.6

m21 Store 21 8.68 10 3x2.5m

m2 LPP-F1-21

3.6

m22 Store 22 7.48 10 3x2.5m

m2 LPP-F1-22

3.6

m19 Electrical

room 1 3.76 10

3x2.5mm2

LPP-F1-19

3.6

m27 Bathroom

1 20.58 25 3x4mm2

LPP-F1-27

4.6

m29 HALL1 1.33 10 2x2.5m

m2 3.6

m37 HALL5 2 10 2x2.5m

m2 3.6

m39 HALL6 1.48 10 2x2.5m

m2 3.6

m41 HALL7 1.33 10 2x2.5m

m2 3.6

m42 HALL8 1.625 10 2x2.5m

m2 3.6

m46

Entrance

8.18 10 2x2.5m

m2 3.6

m47 8.18 10 2x2.5m

m2 3.6

m48 Escalator

3 30.30

3 40

2x10mm2

5.8


201

E L E C T R I C A L

R O O M

2

S M D B - F 2

m7 Store 7 3.71 10 3x2.5m

m2 LPP-F2-7

57.701 80A (3x25+16+16)

mm2

3.6

470.4

60

m8 Store 8 3.71 10 3x2.5m

m2 LPP-F2-8

3.6

m10 Store 10 5.19 10 3x2.5m

m2 LPP-F2-10

3.6

m11 Store 11 3.94 10 3x2.5m

m2 LPP-F2-11

3.6

m12 Store 12 5.19 10 3x2.5m

m2 LPP-F2-12

3.6

m13 Store 13 3.94 10 3x2.5m

m2 LPP-F2-13

3.6

m14 Store 14 4.59 10 3x2.5m

m2 LPP-F2-14

3.6

m15 Store 15 7.81 10 3x2.5m

m2 LPP-F2-15

3.6

m16 Store 16 42.28 63 3x16mm

2 LPP-F2-16

6.8

m23 Store 23 7.48 10 3x2.5m

m2 LPP-F2-23

3.6

m24 Store 24 5.73 10 3x2.5m

m2 LPP-F2-24

3.6

m25 Store 25 5.73 10 3x2.5m

m2 LPP-F2-25

3.6

m26 Store 26 7.48 10 3x2.5m

m2 LPP-F2-26

3.6

m9 Electrical

room 2 6.34 10

3x2.5mm2

LPP-F2-9

3.6

m28 Bathroom

2 20.58 25 3x4mm2

LPP-F2-28

4.6

m31 HALL2 3.045 10 2x2.5m

m2 3.6

m33 HALL3 1.48 10 2x2.5m

m2 3.6

m35 HALL4 1.625 10 2x2.5m

m2 3.6

m44 HALL9 2.95 10 2x2.5m

m2 3.6

m49 Escalator

4 30.30

3 40

2x10mm2

5.8


202

9.3.5 First Floor Emergency Backup Scheme_

The shopping mall is equipped with an emergency backup electrical scheme to avoid mall blackout and

severe under voltage which could harm connected appliances.

During mall black out the emergency lighting will regain function after a limited time no more than 15

seconds which is the time taken by the emergency generator to start. The emergency lighting illuminates

the mall halls and exit stairs which facilitates the easy exit of customers and mall personnel.

The following table shows the emergency panel connected loads which mainly include 50% of Hall way

lighting providing illumination of 75 lux since the mall shops are not equipped with a backup lighting

plan, so this percentage of hallway lighting will provide enough illumination to assure both customer and

personnel safety.

Emergency Panel (Lighting :75 lux) EMDB-F

Place Line Line

current MCB Rating C.S.A

Main Panel

Current

Main MCB

Main CSA

Hall 1 m30e 1.33 10 2x2.5mm2

23.715 32A 2x6mm2

Hall 2 m32e 3.045 10 2x2.5mm2

Hall 3 m34e 1.48 10 2x2.5mm2

Hall 4 m36e 1.625 10 2x2.5mm2

Hall 5 m38e 2 10 2x2.5mm2

Hall 6 m40e 1.48 10 2x2.5mm2

Hall 8 m43e 1.625 10 2x2.5mm2

Hall 9 m45e 2.95 10 2x2.5mm2

Bathroom1 lighting

m50e 1.14 10 2x2.5mm2

Bathroom1 lighting

m51e 1.14 10 2x2.5mm2

Electrical Room 1

m52e 4.1 10 2x2.5mm2

Electrical Room 2

m53e 1.8 10 2x2.5mm2


203


204

9.4 Second Floor_

9.4.1 Second Floor Lighting Calculations_





𝑢∗𝑚∗η

Place Lux Area U m efficacy

(Ƞ) lamp

Power number of lamps

installed number

of lamps

installed wattage

power factor

lamp current

lines

shop 1 300 103.84 0.66 0.8 35 52 32.4168 36 1872 0.8 10.63636 1 , 2

projector 1 150 25.44 0.58 0.8 35 52 4.51876 5 260 0.8 1.477273 3

cinema 1 120 158.03 0.58 0.6 18.6 50 58.5929 70 3500 1 15.90909 4,5,6

cinema 1 0 60 16 16 960 1 4.363636 7

electric room 1

150 6.65 0.5 0.6 80 40 1.03906 2 80 0.8 0.454545 8

stairs 1 150 71.75 - - - - - - - - - -

pop corn 300 11.4 0.5 0.8 35 52 4.6978 6 312 0.8 1.772727 8

cinema hall 150 70.5 0.63 0.8 18.6 50 22.5614 21 1050 1 4.772727 8

information booth

300 16.8 0.5 0.8 80 40 3.9375 4 160 0.8 0.909091 9

bathroom1 300 14.44 0.35 0.8 80 40 4.83482 6 240 0.8 1.363636 9

bathroom2 300 14.44 0.35 0.8 80 40 4.83482 6 240 0.8 1.363636 9

cinema 2 120 157.29 0.58 0.6 18.6 50 58.3204 70 3500 1 15.90909 10,11,12

cinema 2 0 60 16 16 960 1 4.363636 13

projector 2 300 25.85 0.45 0.8 80 40 6.73177 6 240 0.8 1.363636 14

shop 2 300 153.12 0.66 0.8 35 52 47.8022 57 2964 0.8 16.84091 15,16,17

bathroom3 300 14.44 0.35 0.8 80 40 4.83482 6 240 0.8 1.363636 37

shop 3 300 28.49 0.58 0.8 35 52 10.121 10 520 0.8 2.954545 18

shop 4 300 14.06 0.58 0.6 35 52 6.65972 6 312 0.8 1.772727 19

shop 5 300 14.06 0.58 0.8 35 52 4.99479 6 312 0.8 1.772727 20

shop 6 300 14.06 0.58 0.8 35 52 4.99479 6 312 0.8 1.772727 21

shop 7 300 14.06 0.58 0.8 35 52 4.99479 6 312 0.8 1.772727 22

bathroom4 300 14.44 0.35 0.8 80 40 4.83482 6 240 0.8 1.363636 38

electric room 2

300 12.95 0.5 0.6 80 40 4.04688 4 160 0.8 0.909091 39

shop 8 300 12.92 0.58 0.8 35 52 4.58981 6 312 0.8 1.772727 23

shop 9 300 26.52 0.58 0.8 35 52 9.42118 12 624 0.8 3.545455 24

shop 10 300 12.92 0.58 0.8 35 52 4.58981 6 312 0.8 1.772727 25

shop 11 300 13.6 0.58 0.8 35 52 4.83138 7 364 0.8 2.068182 26

shop 12 300 52.5 0.63 0.8 35 52 17.1703 15 780 0.8 4.431818 27


205

shop 13 300 126 0.66 0.8 35 52 39.3357 38 1976 0.8 11.22727 28,29

shop 14 300 20.35 0.58 0.8 35 52 7.2293 8 416 0.8 2.363636 30

shop 15 300 14.06 0.58 0.8 35 52 4.99479 6 312 0.8 1.772727 31

shop 16 300 20.35 0.58 0.8 35 52 7.2293 8 416 0.8 2.363636 32

shop 17 300 56 0.63 0.8 35 52 18.315 19 988 0.8 5.613636 33

shop 18 300 30 0.58 0.8 35 52 10.6574 10 520 0.8 2.954545 34

shop 19 300 30 0.58 0.8 35 52 10.6574 10 520 0.8 2.954545 35

shop 20 300 56 0.63 0.8 35 52 18.315 19 988 0.8 5.613636 36

corridor1 150 282 0.64 0.8 35 26 90.7881 75 1950 0.8 11.07955 40,41,42,43

corridor2 150 104.4 0.64 0.8 35 26 33.6109 38 988 0.8 5.613636 44,45

corridor3 150 169.09 0.64 0.8 35 26 54.4375 44 1144 0.8 6.5 46,47

corridor4 150 74.8 0.64 0.8 35 26 24.0814 22 572 0.8 3.25 48

corridor5 150 75.6 0.64 0.8 35 26 24.3389 22 572 0.8 3.25 49

main hall entrance

- 35 - - - 150 35 35 5250 0.8 29.82955 50,51,52,53,54

ticket booth 150 6 0.5 0.8 80 40 0.70313 2 80 0.8 0.454545 9


206


207

9.4.2 Second Floor Socket Calculations & Wiring_

Main Room Main

current

lighting

Line

lighting current

lighting C.B

lighting C.S.A

socket

line

Socket Line Type

No. of

sockets

socket

current

socket

C.B

sockets C.S.A

m1 shop 1 41.716

line 1

5.318 10 2*2.5 mm2

line 3

normal sockets

7 4.4 10 3*2.5 mm2

line 2

5.318 10 2*2.5 mm2

line 4

power socket

1 20 25 3*4

mm2

line

5 power socket

1 20 25 3*4

mm2

m21

projector 1

23.4202

line 1

1.4772 10 2*2.5 mm2

line 6

normal sockets

2 2.4 10 3*2.5 mm2

cinema 1

line 2

5.3 10 2*2.5 mm2

line 3

5.3 10 2*2.5 mm2

line 4

5.3 10 2*2.5 mm2

line 5

4.363 10 2*2.5 mm2

m41 electric room 1

2.1345 line

1 0.4545 10

2*2.5 mm2

line 2

normal sockets 3

2 2.4 10 3*2.5 mm2

m23

ticket booth

68.6

line 1

0.454 10 2*2.5 mm2

line 2

normal socket 31

3 2.8 10 3*2.5 mm2

pop corn

line 1

1.772 10 2*2.5 mm2

line 2

normal sockets 4

3 2.8 10 3*2.5 mm2

line

3 power

socket 3 1 20 25

3*4 mm2

cinema hall line

1 4.772 10

2*2.5 mm2

information booth

line 1

0.909090909

10 2*2.5 mm2

line 2

normal sockets 5

3 2.8 10 3*2.5 mm2

bathroom1

line 1

1.363 10 2*2.5 mm2

line 2

normal sockets 6

2 2.4 10 3*2.5 mm2

line

3 power

socket 4 1 25 25

3*4 mm2

bathroom2

line 1

1.363 10 2*2.5 mm2

line 2

normal sockets 7

2 2.4 10 3*2.5 mm2

line

3 power

socket 5 1 25 25

3*4 mm2

m22

cinema 2

20.672

line 1

5.3 10 2*2.5 mm2

line 2

5.3 10 2*2.5 mm2

line 3

5.3 10 2*2.5 mm2

line 4

4.772 10 2*2.5 mm2

projector 2 line

5 1.363 10

2*2.5 mm2

line 6

normal sockets 8

3 2.8 10 3*2.5 mm2

m2 shop 2 61.639

line 1

5.613 10 2*2.5 mm2

line 4

normal sockets 9

6 4 10 3*2.5 mm2

line 2

5.613 10 2*2.5 mm2

line 5

power socket 6

1 20 25 3*4

mm2

line 3

5.613 10 2*2.5 mm2

line 6

power socket 7

1 20 25 3*4

mm2

line

7 power

socket 8 1 20 25

3*4 mm2

m43 bathroom3 20.543 line 1.363 10 2*2.5 line normal 2 2.4 10 3*2.5


208

1 mm2 2 sockets 10 mm2

line

3 power

socket 9 1 25 25

3*4 mm2

m3 shop 3 5.474 line

1 2.954 10

2*2.5 mm2

line 2

normal sockets 11

5 3.6 10 3*2.5 mm2

m4 shop 4 4.012727273

line 1

1.772727273

10 2*2.5 mm2

line 2

normal sockets 12

4 3.2 10 3*2.5 mm2

m5 shop 5 4.012727273

line 1

1.772727273

10 2*2.5 mm2

line 2

normal sockets 13

4 3.2 10 3*2.5 mm2

m6 shop 6 4.012727273

line 1

1.772727273

10 2*2.5 mm2

line 2

normal sockets 14

4 3.2 10 3*2.5 mm2

m7 shop 7 4.012727273

line 1

1.772727273

10 2*2.5 mm2

line 2

normal sockets 15

4 3.2 10 3*2.5 mm2

m44 bathroom4 20.543

line 1

1.363 10 2*2.5 mm2

line 2

normal sockets 16

2 2.4 10 3*2.5 mm2

line

3 power

socket 10 1 25 25

3*4 mm2

m42 electric room 2

2.869 line

1 0.909 10

2*2.5 mm2

line 2

normal sockets 17

3 2.8 10 3*2.5 mm2


1 1.772 10

2*2.5 mm2

line 2

normal sockets 18

3 2.8 10 3*2.5 mm2

m9 shop 9 6.06 line

1 3.54 10

2*2.5 mm2

line 2

normal sockets 19

5 3.6 10 3*2.5 mm2


1 1.772 10

2*2.5 mm2

line 2

normal sockets 20

3 2.8 10 3*2.5 mm2


1 2.068 10

2*2.5 mm2

line 2

normal sockets 21

4 3.2 10 3*2.5 mm2


1 4.43 10

2*2.5 mm2

line 2

normal sockets 22

7 4.4 10 3*2.5 mm2

m13 shop 13 42.307

line 1

5.6135 10 2*2.5 mm2

line 3

normal sockets 23

7 4.4 10 3*2.5 mm2

line 2

5.6135 10 2*2.5 mm2

line 4

power sockets 11

1 20 25 3*4

mm2

2*2.5 mm2

line 5

power sockets 12

1 20 25 3*4

mm2


1 2.363 10

2*2.5 mm2

line 2

normal sockets 24

4 3.2 10 3*2.5 mm2


1 1.772 10

2*2.5 mm2

line 2

normal sockets 25

4 3.2 10 3*2.5 mm2


1 2.363 10

2*2.5 mm2

line 2

normal sockets 26

6 4 10 3*2.5 mm2

m17 shop 17 8.413636364

line 1

5.613636364

10 2*2.5 mm2

line 2

normal sockets 27

6 4 10 3*2.5 mm2


1 2.95 10

2*2.5 mm2

line 2

normal sockets 28

7 4.4 10 3*2.5 mm2


1 2.95 10

2*2.5 mm2

line 2

normal sockets 29

7 4.4 10 3*2.5 mm2

m20 shop 20 8.693636364

line 1

5.613636364

10 2*2.5 mm2

line 2

normal sockets 30

7 4.4 10 3*2.5 mm2

m24

corridor1

2.77 line

1 5.539 10

2*2.5 mm2

m25 2.77 line

2 5.539 10

2*2.5 mm2

m26 2.77 line

3 5.539 10

2*2.5 mm2

m27 2.77 line

4 5.539 10

2*2.5 mm2

m28

corridor2

2.807 line

1 2.807 10

2*2.5 mm2

m29 2.807 line

2 2.807 10

2*2.5 mm2

m30 corridor3 3.25 line

1 3.25 10

2*2.5 mm2


209

m31 3.25 line

2 3.25 10

2*2.5 mm2

m32

corridor4

1.625 line

1 1.625 10

2*2.5 mm2

m33 1.625 line

2 1.625 10

2*2.5 mm2

m34

corridor5

1.625 line

1 1.625 10

2*2.5 mm2

m35 1.625 line

2 1.625 10

2*2.5 mm2

m36

main hall entrance

5.964 line

1 5.964 10

2*2.5 mm2

m37 5.964 line

2 5.964 10

2*2.5 mm2

m38 5.964 line

3 5.964 10

2*2.5 mm2

m39 5.964 line

4 5.964 10

2*2.5 mm2

m40 5.964 line

5 5.964 10

2*2.5 mm2

9.4.3 Second Floor Local Feeders_

Line Room Current MCB C.S.A (1ph+n+e)

m1 shop 1 41.7 63 3x10mm2

m21 projector 1

23.4202 25 3x4mm2 cinema 1

m41 electric room 1 2.2254 10 3x2.5mm2

m23

ticket booth

68.6 80 3x25mm2

pop corn

cinema hall

information booth

bathroom1

bathroom2

m22 cinema 2

20.672 25 3x4mm2 projector 2

m2 shop 2 61.639 63 3x10mm2

m43 bathroom3 20.543 25 3x4mm2

m3 shop 3 5.474 10 3x2.5mm2

m4 shop 4 4.012727273 10 3x2.5mm2

m5 shop 5 4.012727273 10 3x2.5mm2

m6 shop 6 4.012727273 10 3x2.5mm2

m7 shop 7 4.012727273 10 3x2.5mm2


210

m44 bathroom4 20.543 25 3x4mm2

m42 electric room 2 2.869 10 3x2.5mm2

m8 shop 8 3.732 10 3x2.5mm2

m9 shop 9 6.06 10 3x2.5mm2

m10 shop 10 3.732 10 3x2.5mm2

m11 shop 11 4.308 10 3x2.5mm2

m12 shop 12 7.51 10 3x2.5mm2

m13 shop 13 42.307 63 3x10mm2

m14 shop 14 4.603 10 3x2.5mm2

m15 shop 15 4.012 10 3x2.5mm2

m16 shop 16 5.163 10 3x2.5mm2

m17 shop 17 8.413636364 10 3x2.5mm2

m18 shop 18 6.03 10 3x2.5mm2

m19 shop 19 6.03 10 3x2.5mm2

m20 shop 20 8.693636364 10 3x2.5mm2

m24

corridor1

2.77 10 2x2.5mm2

m25 2.77 10 2x2.5mm2

m26 2.77 10 2x2.5mm2

m27 2.77 10 2x2.5mm2

m28 corridor2

2.807 10 2x2.5mm2

m29 2.807 10 2x2.5mm2

m30 corridor3

3.25 10 2x2.5mm2

m31 3.25 10 2x2.5mm2

m32 corridor4

1.625 10 2x2.5mm2

m33 1.625 10 2x2.5mm2

m34 corridor5

1.625 10 2x2.5mm2

m35 1.625 10 2x2.5mm2

m36

main hall entrance

5.964 10 2x2.5mm2

m37 5.964 10 2x2.5mm2

m38 5.964 10 2x2.5mm2

m39 5.964 10 2x2.5mm2

m40 5.964 10 2x2.5mm2


211

9.4.4 Second Floor SMDBs_& Cable Tray Dimension_


room consists of one service panel board "SMDB-S1" where the S indicates that this

panel board is in the second floor and the numeral 1 indicates that this service panel is


panel board "EMDB-S". The second electrical room consists of only one service panel

"SMDB-S2". The service and emergency panel's enclosures are compliant with the

standards "service enclosure Ip40 (NEMA1)"

Line Room Curren

t

M C B

C.S.A (1ph+n+e)

Panel Code

Service Panel Main

current (per

phase)

Service

Panel 3ph

MCCB Rating


(3ph+n+e)

Cable Overall Diamet

er

Cable

Tray Widt

h (mm)

Installed

Cable Tray

Width (cm)

E L E C T R I C A L

R O O M 1

S M D B - S 1

M 1

shop 1 41.7 63 3x10mm2 LPP-S1-1

88.22053333

100A (3x35+16+16)

mm2

5.8

391.2

50

m2 shop 2 61.63

9 63 3x10mm2 LPP-S1-2 5.8

m14 shop 14 4.603 10 3x2.5mm2 LPP-S1-14 3.6

m15 shop 15 4.012 10 3x2.5mm2 LPP-S1-15 3.6

m16 shop 16 5.163 10 3x2.5mm2 LPP-S1-16 3.6

m21

projector 1 23.42

02 25 3x4mm2 LPP-S1-21 4.6

cinema 1

m22

cinema 2 20.67

2 25 3x4mm2 LPP-S1-22 4.6 projector

2

m23

ticket booth

68.6 80 3x25mm2 LPP-S1-23 8.4

pop corn

cinema hall

information booth

bathroom1

bathroom2

m28 corridor2 2.807 10 2x2.5mm2 3.6

m36

main hall entrance

5.964 10 2x2.5mm2 3.6

m37 5.964 10 2x2.5mm2 3.6

m38 5.964 10 2x2.5mm2 3.6

m39 5.964 10 2x2.5mm2 3.6

m40 5.964 10 2x2.5mm2 3.6

m41 electric room 1

2.2254

10 3x2.5mm2 LPP-S1-41 3.6


212

E L E C T R I C A L

R O O M 2

S M D B - S 2

m3 shop 3 5.474 10 3x2.5mm2 LPP-S2-3

58.11206061

80A (3x25+16+16)

mm2

3.6

522 60

m4 shop 4 4.012727

10 3x2.5mm2 LPP-S2-4 3.6

m5 shop 5 4.012727

10 3x2.5mm2 LPP-S2-5 3.6

m6 shop 6 4.012727

10 3x2.5mm2 LPP-S2-6 3.6

m7 shop 7 4.012727

10 3x2.5mm2 LPP-S2-7 3.6

m8 shop 8 3.732 10 3x2.5mm2 LPP-S2-8 3.6

m9 shop 9 6.06 10 3x2.5mm2 LPP-S2-9 3.6

m10 shop 10 3.732 10 3x2.5mm2 LPP-S2-10 3.6

m11 shop 11 4.308 10 3x2.5mm2 LPP-S2-11 3.6

m12 shop 12 7.51 10 3x2.5mm2 LPP-S2-12 3.6

m13 shop 13 42.30

7 63 3x10mm2 LPP-S2-13 5.8

m17 shop 17 8.413636

10 3x2.5mm2 LPP-S2-17 3.6

m18 shop 18 6.03 10 3x2.5mm2 LPP-S2-18 3.6

m19 shop 19 6.03 10 3x2.5mm2 LPP-S2-19 3.6

m20 shop 20 8.693636

10 3x2.5mm2 LPP-S2-20 3.6

m24 corridor1

2.77 10 2x2.5mm2 3.6

m26 2.77 10 2x2.5mm2 3.6

m30 corridor3 3.25 10 2x2.5mm2 3.6

m32 corridor4 1.625 10 2x2.5mm2 3.6

m34 corridor5 1.625 10 2x2.5mm2 3.6

m43 bathroom

3 20.54

3 25 3x4mm2 4.6

m44 bathroom

4 20.54

3 25 3x4mm2 4.6

m42 electric room 2

2.869 10 3x2.5mm2 LPP-S2-42 3.6


213

9.4.5 Second Floor Emergency Backup Scheme_

The shopping mall is equipped with an emergency backup electrical scheme to avoid mall blackout and

severe under voltage which could harm connected appliances.

During mall black out the emergency lighting will regain function after a limited time no more than 15

seconds which is the time taken by the emergency generator to start. The emergency lighting illuminates

the mall halls and exit stairs which facilitates the easy exit of customers and mall personnel.

The following table shows the emergency panel connected loads which mainly include 50% of Hall way

lighting providing illumination of 75 lux since the mall shops are not equipped with a backup lighting

plan, so this percentage of hallway lighting will provide enough illumination to assure both customer and

personnel safety.

Emergency Panel (Lighting :75 lux) EMDB-S

Place Line Line

current MCB Rating C.S.A

Main Panel

Current

Main MCB

Main CSA


32.206 40A 2x10mm2

m27e 2.77 10 2x2.5mm2

Corridor 2 m29e 2.807 10 2x2.5mm2


Corridor 4 m33e 1.625 10 2x2.5mm2

Corridor 5 m35e 1.625 10 2x2.5mm2

Cinema 1 m45e 8 20 2x4mm2

Cinema 2 m46e 8 20 2x4mm2

Electrical Room 1

m47e 0.45

10 2x2.5mm2

Electrical Room 2

m48e 0.909 10 2x2.5mm2


214


215

9.5 Air Conditioner and Elevator Panel (Roof Panel) _

The air conditioning scheme of the mall is composed of 15 shellers, each with an

expected current of 154.988 which is based on the approximate prediction of

mechanical engineers which is 600 KVA for the whole mall.

Roof Panel (SMDB-R)

Line Room Current MCCB &

MCB C.S.A

Service Panel Main current (per

phase)

Service Panel 3ph

MCCB Rating


(3ph+n+e)

m1

Air Cond.

154.988 200 2x95mm2

547.7593333 630A (3x300+150)mm2

m2 154.988 200 2x95mm2

m3 154.988 200 2x95mm2

m4 154.988 200 2x95mm2

m5 154.988 200 2x95mm2

m6 154.988 200 2x95mm2

m7 154.988 200 2x95mm2

m8 154.988 200 2x95mm2

m9 154.988 200 2x95mm2

m10 154.988 200 2x95mm2

m11 154.988 200 2x95mm2

m12 154.988 200 2x95mm2

m13 154.988 200 2x95mm2

m14 154.988 200 2x95mm2

m15 154.988 200 2x95mm2

m16 Elevator 22.72 32 2x6mm2

9.6 Mall Panel Boards Connection Diagram & Cable Specifications_

Mall Cables are based on two types of cables which lay in two parts. The first type

of chosen cables is 450/750 Volts PVC 85"C insulated with copper conductor Single

core Solid or Stranded Up to 6 mm2 and Stranded up to 630 mm2, this type is used

for the connections between the floor service panels and the "SMDB's" and mall loads

which are represented in floor lighting and store feeders. The second type of cables is

600/1000 Volts Single core (cu) PVC 85"C insulation - PVC sheath, this type is used

in the rest of the mall wiring as shown in the diagram, it should also be noted that

cables are placed in cable trays and an assumptions is made that the cable is exposed

to the worst possible conditions when using the cable tables to provide us with a good

safety margin.


216

Panel Current (per

phase) MCCB (3-

ph) Riser CSA (3ph+n+e)

Mall Current (per phase)

MCCB (3ph)

Mall Feeder

ER's 1 PB 270.65 320A (3x240+120+120)mm2

1032.239333 1600A 4x(3x300+150)

ER's 2 PB 180.99 200A (3x120+70+70)mm2

SMDB-R 547.7593333 630A (3x300+150)mm2

E-Panel 32.84 80A (3x25+16)mm2

SPARE 320 (3x240+120+120)mm2


217


218

9.7 Detailed Single Line Diagram of Each Panel Board_


219

9.7.1 Electrical Rooms 1 Panel Boards_


220

9.7.2 Electrical Rooms 2 Panel Boards_


221

9.7.3 Emergency Panel Boards_


222

9.8 Emergency Operation_

In case of a black out or a fault ,safety must be provided for both customers and mall

personnel so we built our emergency operation scheme on basis of immediate

evacuation of the mall during black out, so we provided emergency illumination for

hallways and stairs ,also an emergency cable was provided to the cinema in order to

insure the safe evacuation of cinema viewers in case of occurrence of a blackout .The

emergency hallways' illumination is 75 lux which is very sufficient for evacuation

keeping in mind that stores' emergency plan is left to their decision in this matter, so

as a worst case scenario that store owners don’t equip their stores with a back up

electrical plan ,we provided sufficient illumination in the hallways ,which is 50% of

normal hallway illumination.

9.8.1 ATS specifications_

The used ATS in the Mall is of the brand "ZTE Automatic Transfer Switches". The

chosen standard is "Standard Open Transition" which is characterized by double

throw, solenoid operated, Break-before-Make mechanism. The chosen ATS rating is

100A which can transfer 66KVA which is very sufficient for our emergency loads

which are 21.67 KVA. This margin is chosen in order to accommodate any future

loadings on the emergency scheme.

The automatic transfer switch continually monitors the incoming utility power. Any

anomalies such as voltage sags, brownouts, spikes, or surges will cause the internal

circuitry to command a generator to start and will then transfer to the generator when

additional switch circuitry determines the generator has the proper voltage and

frequency. When utility power returns or no anomalies have occurred for a set time,

the transfer switch will then transfer back to utility power and command the generator

to turn off, after another specified amount of "cool down" time with no load on the

generator.

9.8.2 Emergency Generator_

The Chosen generator rating is 50 KVA which is more than double the current

emergency load in order to accommodate any future loading on the emergency

scheme.

http://en.wikipedia.org/wiki/Power_outage

chapters 1 to 9

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