voltage stabliser

8/1/2019 Voltage Stabliser

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INTRODUCTION

In future there is a possibility of voltage drop in electrical supply so as to avoid such situation

a project on VOLTAGE STABILIZER is being made.Its main function is to use the electrical supply

in a more safer way on the electrical instrument in a automatic and manual way By using this

voltage stabilizer accurate output supply i.e.230 volt is being received in the out put.lf input

voltage is less then 170 volts then also we vill receive 230 voit But if we receive more 230

volts then in this condition this stabilizer will switch all/the electrical and electronics

equipments. The moment it receives 230 volts it automatically again restart the electrical

equipments. In future it is a very useful, trustful and very small but a very durable

project.


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RESISTORS

INTRODUCTION:

Resistor is a component, used to limit the amount of current or divide the voltage in an

electronic circuit, The ability of resistor to oppose the current is called resistance. The unit

resistance R is ohm for which the symbol is [the Greek capital letter omega].The schematic

symbol of R is shown in figure-

o------^^^^^-------o

TYPES OF RESISTORS:

Each resistor has two main characteristics i.e. its resistance [R] in oluns of its power rating in

watts [w] The resistor having wide range of resistance [from a friction of an ohm to many mega

ohms]are available. The power rating may be as lower 1/10w to as high as several hundred

watts. The value of R is selected to obtain a desired current I or voltage dropper in the circuit.

At the same time wattage of the resistor is selected so that it can dissipate the heat losseswithout over heating it self. Too much heat may burn the resistor. From the operating condition

point of view, the resistor may be classified as fix resistor and variable resistor.[A] Fixed

Resistor: The resistor which have fix value of resistance are called fixed resistors. These

resistors may be carbon composition resistor or wire wound resistor.


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Carbon composition resistor: Most common in electronic circuits are carbon resistors with a

low power rating [2w or less].This type of resistor is made of mixture of carbon as graphite anddry.

The two materials are mixed in the proportions needed for the desired value of r.The resistor

element is enclosed in a plastic case for insulation and mechanical strength. The leads made

of tined copper are joined to the two ends of carbon resistance element.

This type of resistors are readily available in values ranging. from 1 ohm to 22 ohm, having a

tolerance range of 5 to 20 percent. The power rating is generally 1/4, 1/2 , 1 or 2w. The relative

size of resistors with higher wattage increase since they are to carry more current and

dissipate higher losses [heat losses].The relative size of carbon composition resistor fordifferent wattage rating. These resistors are quite cheap in cost. A resistor may cost as 50 paisa

even less than this.

The other variety of carbon composition resistors is film type resistors. The basic structure of

this type of resistor is shown in figure. A homogeneous film of pure carbon [or some metallic]

deposited over a ceramic or other insulating core. Only approximate value of resistance is

obtained by this method. To obtain the desired value either the layer is trimmed off or a helical

grove of suitable pitch along its length is cut. Thus very accurate value [with an accuracy of+1%]

of resistance can be obtained, therefore these resistors [film type resistors] are sometimes

called precision type resistors.


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As the shaft of the control is turned, the variable arm moves the wiper to make contract at

different paints on the resistor element which changes the value of resistance interested in thecircuit. The carbon composition variable are available with 1000 ohms to 5 m ohm approx

having power rating o usually to 2 w. A carbon control [resistor] is often combined eighth

power off switch.

Wire wound variable resistors: A wire wound variable resistors and its symbol is shown in. In

this case, a resistance wire is wounded over a dough shaped core of backlight or ceramic. The

two ends of the resistance wire are joined to the external soldering lug tensional 1 and 3.The

middle tensional is connected to the variable arm that contracts the resistors elementals the

Shaft of control is turned, the variable arm moves the wiper to make contract at differentpoints on the resistor element shish changes the value of resistances.

Adjustable wire wounded resistors are also available in which the resistance may be

varied with an adjustable slider moved along exposed portion of the winding. The variable

resistors can be either linear or non linear.


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CAPACITORS

INTRODUCTION:

The two conducting plates separated by an insulating materials [called dielectric]

forms a capacitor. The basic purpose of a capacitor is to store the charge. The capacity

of a capacitor to store change per unit potential difference is called its capacitance. The

unit of capacitance is farads[F]However, the unit farad being too large the capacitors

are specified practically in micro farads {uf} or Pico farads [pf].

A capacitor is a component which offers low impedance to a.c. but very high

impedance [resistance] to d.c. In most of the electronic circuits a capacitor has d.c.

voltage applied, confined with a niche smaller a.c. signal voltage. This usual function of

the capacitor is to block the d.c. voltage but pass the c signal voltage, by means of

charging and discharging. These applications include coupling by passing and filtering

for a.c. signal. The schematic symbol of fixed and variable capacitor [c].


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DIAGRAM OF CAPCITER


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All the capacitors have two main characteristics i.e. their capacitance [c] in

farads [or f or pf] and their operating voltage. The commercial capacitors aregenerally classified according to the dielectric. Some of the most commonly used

capacitors are purer, mica, ceramic, electrolytic and air. Like resistors capacitors

can also either be fixed or variable type. The variable capacitor are mostly air gang

capacitors. There is no required polarity is since either side can be made positive

plate, except for electrolytic capacitors. In electrolytic capacitors, polarity is

marked which indicates the side which must be considered as positive. It

maintains the internal electrolytic action that prodigies the dielectric [a thin oxide

film] required to form the. capacitance.

[A] Paper capacitors: Perhaps paper capacitors are the most common of all

capacitors. For the construction of all the capacitors two metal [aluminum or tin]

foils separated by paper impregnated with a dielectric material such aswax.Plastic

or oil are rolled into a compact cylinder is generally placed in a card board

container coated aith wax encased in plastic. A tabular type paper capacitor: A

tabular type paper capacitor. A typical[430p1]Encapsulated type paper capacitor.

Paper capacitors are available in wide range of capacitance values and voltageratings. Typical capacitance values ranging from 0.0001 uf to 1.0 uf having

tolerance of +10% usually with voltages ratings ranging from 200 to 10000 volts

and more. There leakage resistance is of the order of 100m ohms.The.physical

size for [f is typically]2.5 cm long with 1 cm diameter.


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These capacitor should not be used in radio frequency tuned circuit because

they are not electrically stable enough.

A black kind at one end of paper capacitor the lead connected to the outside

foil. This lead should be used for the ground or low potential side of the circuit to

take advantage of shielding by the outside foil however, there is no required

polarity, since the capacitance is the same no matter which side is grounded.

[B] Mica capacitor:

These capacitors consist of all alternate thin sheets of metal [aluminum or tin]foils

separated by thin mica sheets.Alternate metal sheets are connected together and

brought out as one terminal for one set of plates, while the opposite terminal

connects to the other set of plates. The entire unit is generally encased in the

plastic housing or mounded inbakelight case. In silver-mica capacitors, the

opposite faces of the mica sheets are silver coated [which acts as the conducting

material].

Mica capacitor are often used for small capacitance values ringing 50 to 500 pf

having tolerance of +2 to +20% usually, with voltage ratings ranging from 200 to

1000v. The leakage resistance of mica capacitors is of the order of 1000 mega-

ohms that is why their, leakage current is very small.


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These capacitors are very small in size having 10mm length and 3mm

tl1ickness.Typical mica capacitor. These capacitors Are used extensively in

rf tuned circuits, since they are considerably more stable electrically thanfoil type capacitors and are used in high stability frequency determining

circuits. Silver mica capacitors

Are available in tolerances ranging from +5% to +1% or better.

[C] Ceramic capacitors: The ceramic is a dielectric material made from earth

fired extreme heat: Titanium oxide or several other types of silicates are used

to obtain very high value of dielectric of ceramic material. The ceramic

capacitors may be of disc types or tabular type these capacitor are alsoavailable in other shapes.

In the disc type, a ceramic disc coated on two sides with a metal [silver or

copper] Tinned copper wire leads are attached to each coating which act a

electrodes or plates and then the entire unit is en capsulates in a protective

coating [plastic] and marked with its capacitance value, either using

numerals or a color code. The coding is similar to that used for resistances.


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COLOUR SIGNIFICANT

DIGIT

MULTIPLIER TOLERANCE

Black 0 100=1 -Brown 1 101=10 -

Red 2 102=100 -

Orange 3 103=1000 -

Yellow 4 104=10000 -

Green 5 105=100000 -

Blue 6 106=1000000 -

Violet 7 107=10000000 -

Gray 8 108=100000000 -

White 9 109=1000000000 -Gold - 10-1=0.1 +_5%

Silver - 10-2=0.01 +_10%

No colour - - +_20%


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RELAY

INTRODUCTION :

Relays is a device means of which an electric circuit can be controlled(opened and

closed ) by the change in the same circuit or other circuit. An electro mechanical

relay, has one or more coils, movable elements, contact system, etc ....

The operation of such relay depends weather the opening torque/ force is

greater than the restraining torque/ force i.e.

The relay operates, if net force F in eq.1 blew is positive or net T in eq.2 below in

positive .

F = Fa- Fr .......................1

E = Net force

Fa = Operating force

Fr = Restraning force

T = Ta - Tr .......................2


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T =Net Torque

Ta = Operating Torque

Tr = Restraining torque

Relay operates when operating force > Restraining force

In electro mechanical relays, the operating torque is produced by electro

magnetic attraction / thermal effects of electric current. These restring torque is

given by springs .the various terms such a measuring relay, All or-nothing relay,

trip circuit, time lag relay , instantaneous relay , etc.....

The contact circuit of electromechanical

relays are quit complex .


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MEASUREMENT IN RELAYS

The discrimination involves measurement of actuating quantities (voltage and

current )which are present at the relaying point. the measurement in majority of

protective relays can be grounded as follows :

- Magnitude measurement such as over current, over voltage, under

current.

- Product measurement such as power (vl cos 0)

- Ratio measurement such as impedance (v/1)

- Comparison between similar electrical quantities such as vector

difference between currents 1,1 .


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TYPES OF RELAY UNITS

(b) Balanced beam(electromagnetic)relay.

(c) Induction dies (electromagnetic ) relay .

(d) Induction cup (electromagnetic) relay .

MOVING COIL A

(a) Attracted armature type (electromagnetic)relay

(c) nd moving iron (electromagnetic) relay .

(f) Gas operated (buchholz) relay ( gas pressure)

(g) Rectifierrelays (rectifier plus moving coil unit ) .

(h) Static relay (static electronic circuit for measurement).

The electro-magnetic relay operates when operating torque / force ex- ceeds

the restraining torque / force .


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VOLTMETER

O to 300 volts. This volt is manufactured on the principal of "inductance". The am

work of volt is to measure the output voltage of the stabilizer.

The volt meter consists of indicating needle, measurement scalr and they are

attached to inductor and load resistance .

All these parts constitute the voltmeter.


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TRANSISTORS

INTRODUCTION :-

it is a contraction of two words- transfer and resistor. It is so because

a transistor is basically a resister that amplifies electrical impulses as they are

transferred through its input to output terminals.

Basically it consists of two back N junctions give rise to three regions called

emitter, base and collector. The emitter , base and collector

are provided with terminals which are labeled as E,BLC. The two junctions are-

Emitter Base [E / B] junction and Collector Base [C/B] junction.

In a transistor for a normal operation collector and base have the.

same polarity with respect to emitter. Types of transistor

[A] A layer of N type materials sandwiched between two layers of P types

materials. It is described as PNP transistor

[B] A layer of P type material sandwiched between two layers of P types

materials . It is described as NPN transistor. The symbol employed for PNP

and NPN transistor .


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TRANSFORMER

Introduction :

Transformer is the main component of any voltage stabilizer. The main function

of transformer is either to "step up" or "step down" the input voltage. Normally

there are two separate wire coils in a transformer. In the process input supply is

given to one coil while output is taken from another.

The coil which is given input A.C. supply is called the primary coil and coil from

which output supply is taken is called the secondary coil.


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CIRCUIT DIGRAM OF TRANSFORMER


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WORKING OF TRANSFORMER

The output voltage received from the secondary coil is less as compared tothe input supply given to the primary coil of a step down transformer butsecondary coil can produce more current then the primary coil. For thisurposethe thickness of the wire of the secondary coil is kept more ascompared to primary.

Step up transformer is just opposite to adverse to the step downtransformer. This transformer gives more voltage to secondary coil ascompared to primary coil but its capacity to supply current is less. The valueof electricity transform from primary to secondary depends upon the corearea of the transformer. This power is recorded in "volt amperes".

The efficiency of a transformer is approximately 90%.Theremaining 10% of electrical energy is used up for heating thetransformer. Which might harm the transformer


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TRANSFORMER USED IN STABILIZER

In most of stabilizers autotransformer is used.lt consists of only one bindingwhere in separate tapings remain open for different voltages. Among these thereis one end for zero volts which is common to all and the remaining 8ends have the following voltages:

180 volts190 volts200 volts210 volts220 volts230 volts240 volts250 volts

These type of auto transformer are used in automatic stabilizers.

IDENTIFICATION OF AUTO TRANSFORMER :-

Ussualv auto transformer has 9 wire winding in it.lf we keep the millimeter in thecontinuity measuring range and fix one end to the common and other endbetween 180 volt to 250 volts. We get the continuity each time. So treadle of the

meter will point towards right side. When the transformer is required to beinstalled or requires a change then it becomes necessary to identify all the endsfailing which any wrong wiring may damage the transformer.


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TRANSFORMER

Introduction :

Transformer is the main component of any volt stabilizer. The mainfunction of transformer is either to "step up" or "step down" the inputvoltage.

Normally there are two separate wire coils in a transformer. In theprocess input supply is given to one coil while output is taken from another.

The coil which is given input A.C. supply is called the priinan coil and coil fromwhich output supply is taken is called the secondarv coil.

The transformer is a statics piece of apparatus by means of whichelectric power in one circuit is transformed in to electric power of the samefrequency in another circuit. It can raise or lower the voltage in a circuit but

with a corresponding decrease or increase in current.


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THE WORKING PROCESS OF AUTO TRANSFORMER:

Each type of transformer work on the principle of mutual inductance. When 220volt is supplied between common end and 220 volt it creates magnetic effect inthe core rest all the windings gives the noted voltage. At present the windingsbetween common end and 220 volt are working as primary winding. If the supplyis reduced by 10 volt that is from 220 volt to 210 volt then the supply betweeneach winding will also be reduced by 10 volt.

In this condition if the supply is given between conunon end and 210 volt end,again the noted voltage will be received on all the windings, similarly if 10 volt ofsupply is raised that is 220 volt to 230 volt then the noted voltage across eachwinding will be increased by 10 volts. If this 230 volt supply is given between 230volt end then again we will get the normal voltage.

The main demerit of this auto transformeris that it has no isolationbetween input and output supply. That is why such type of transformers 2

should only be used where "ELECTRICAL ISOLATION" is not at allnecessary.


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First of all, all the common end is indentified in an auto transformer. It shouldbe kept in mind that in auto transformer that thin wire winding is usedbetween common end and 180 volt. Where as relatively thick wire is usedbetween 180 volt to 250 volt. In this way it becomes very easy to locate thecommon end and the 180 volt end. Because in common end there is only onethin wire remains protruding where as in 180 volt end there remains twowires protruding one thin and one thick.

Apart from this there are two wires each remain there between the range of190volt to 240 voh and cach 01 wire between this range are relatively thickerthen the common wire. After this there is only one thick wire for 250 volt or thelast end.

These can also be identified by measuring the voltages on different tapings of theauto transformer. For this it is necessary to locate the common end and first endthat is 180 volt end. Now a supply of 180 volt is given between these two ends byany other transformer or stabilizer and the supply given is checked by the meter.

The other end which gets 10 volt more supply the 180volt end is cod number 2.Inthis way the increasing series helps to identify each end.


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Transformer works on the principle of "electromagnetic induction" by whichan e.m.f is induced in any coil which is linking with a changing flux. If onecoil is connected to a source of alternating voltage an alternating flux is setup in the laminated core, most of which is linked with the other coil in whichit produces mutually induced cmf (according to faraday's law ofelectromagnetic induction).

If the second coil circuit is closed a current flows in it and so electrical energy istransferred (entirely magnetically) from the first coil to the second coil .The first

coil in which electrical energy is fed from the u.c supply mains, is called primarywinding and the other from which energy is drawn out is called secondarywinding.

Constructionally the transformer are of two general types, distinguished fromeach other merely by the manner in which the primary and secondary coils areplaced around the laminated core. The two types areknown as:

(1) Core type.(2) Shell type.


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PREFACE

All tough the topic of the project prepared by us in not new. It put forth

many new ideas and reflect and theoretical as well as practical learned by usduring the course of education in the institution.Project in the diploma course generates confidence in working. An

important aspect of any project that it not only gives an ideas for designing andmanufacturing as it gives some new technical ideas and impressed technical tothem.

Being the students of final year electrical engineering we have selectedMANUAL AUTO CUT STABILIZER

voltage stabliser

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