energy engg_meralco literature-01

8/14/2019 Energy Engg_meralco Literature-01

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Electricity. Its something we use everyday, and is part of our daily lives. Just what is it?

Electricity is a form of energy, just like heat, light or mechanical energy. Electricity can be fou

not just in your sockets, wires and batteries.

Atoms, basic building blocks of matter consist of positively charged protons, uncharged parti

and surrounding this are negatively charged particles called electrons. In its stable form, all atamount of protons and electrons, but if this balance is upset by an outside force, the atom

charge, depending on whether a proton or an electron was lost or added. In an instance when athis free flowing charge becomes an electric current.

The study of electricity has been around since the time of the Greeks. In fact The word "electricGreek Word "electron", meaning amber (a fossilized resin). When rubbed with wool cloth

observed that it attracted bits of materials such as pieces of straw and leaves.

Modern studies on electricity began with Benjamin Franklins experiment with a kite, a key an

inventor, Thomas Edison, changed everyones life when he invented the electric light bulb. Nikthe pioneer of the use, generation and transmission of alternating current (AC) electricity. His

the backbone for modern use of electricity.

Measuring electricity can be tricky, because its something you dont really see. We use the term

James Watt, the inventor of the steam engine as the basic unit of power. One watt is a minute afact, it takes about 750 watts to equal one horsepower. Using the metric standard, one kilowa

watts. A kilowatt-hour (kWh) is equivalent to the energy of 1,000 watts working for one hour. Tunit of measurement for the amount of power generated by a power plant, and how much a h

period of time. Computing kWhs are easy. Take the wattage of an appliance and multiply ihours used, and divide it by 1000. (i.e. 50-watt light bulb 5 hours a day = 200watts or 0.2kWh.

Below are some common terms used when we talk about electricity:

Definitions

ElectricityThe energy used to run household appliances and industrial machinery; can produce light, so

serve numerous other uses.

Current


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Is the flow of electricity through a circuit, either AC or DC.

Alternating Current

Is an electric current reversing its direction of flow at regular intervals. For example, it wouldevery second in 60-cycle system. This type of current is commonly found in homes.

Direct CurrentIs an electric current flowing in one direction. This type of current is commonly found in industri

AmpereUnit used in measuring intensity of flow of electricity. Symbol for it is "I".

VoltUnit used for measuring electrical pressure or force, known as electromotive force. Symbol for it

ResistanceRestricts the flow of current; unit of resistance is Ohm. The more resistance, the less current flo

WattUnit of electric power, Volts x Amperes = Watts

CircuitFlow of electricity through 2 or more wires from the supply source to one or more outlets and ba

ConductorAny substance capable of carrying an electric current. In the home, copper wire is usually used.

WiresConductors carrying the electric current or power to the load.

InsulatorMaterial that will not permit the passage of electricity.

CircuitSafety device used to break the flow of electricity by opening the circuit automatically in the ev

or used to open or close it manually.

Fuse

Safety device that cuts off electricity when the current flowing through the fuse exceeds its rate

Ground

To connect with the earth as to ground an electric wire directly to the earth or indirectly tconductor. Usually a green-colored wire is used for grounding the whole electrical system to the

is usually used to ground individual or electrical components of the whole system.

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Did you know that electric generators havebeen around for quite some time?

Michael Faraday (1791-1867)was the first scientist who discoveredthat electromagnetic induction can convertmechanical energy to electrical energy, and this was way back

in 1831

The concept is very simple:

if an electric conductor, like a copper wire is

moved thru a magnetic field, electric currentwill flow. The mechanical energy of the moving

wire is converted into an electric energy via thecurrent that flows in the wire.

Take a look at this diagram:

We have 2 magnets, creating the magneticfield.

A tightly wound copper wire coil.

Wires which harness the electricity produced by

the movement of the copper wire coil,

And a hand crank to turn the copper wire coil.

Presently, there are many ways of "turning

the crank.

Some applications include:

Hydroelectric Plants - that use the flow ofwater stored in the dam to turn the turbines.

Geothermal Plants - that harness the natural

steam coming from the earth.


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Nuclear Power Plants - that uses nuclearchain reaction to heat water to produce steam

that will turn the turbines.

And Coal Fired Power Plants - that burns coalto boil water and create steam to turn theturbine.

In the Philippines, we are currently usingall of these, with the exception of the nuclear

power plant.

An amazing invention back in 1831 and still isan amazing machine.

This is what powers up our daily lives.

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THE POWER DISTRIBUTION GRID.

The power distribution grid is the complexsystem that brings electricity from the power

plants to factories, offices, homes and otherplaces.

THE POWER PLANT

This is where it all starts. Electricity is producedin power plants through large power generators

A generator is a machine composed of wires

and magnets that converts mechanical energyto electric energy.

Electricity is produced by the generator as itspins. This may be done by wind mill, water

turbine (in hydroelectric plant),
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gas turbine, steam turbine (in thermal plant)and diesel engines.

TRANSMISSION SUBSTATION

From generators to consumers, electricity musttravel long distances. To travel efficiently, its

voltage is increased to very high levels through

step-up power transformer in the transmissionsubstation.

Why do you need high voltages?

Voltage can be likened to a water pressure. In avery long water hose, you will need a very high

water pressure in order to push water to theend. Similarly, you need high voltages to push

electricity to the other end. If low voltage isused, what used to be 220 volts from the

source can be 10 volts on the other end. Or onecan use very large wires to maintain the voltage

up to the other end, but that wont beeconomical.

TRANSMISSION LINES

From the transmission substation, electricity is

brought to different towns and cities throughhigh voltage transmission lines. A typical

transmission distance is around 300 kilometers.Typical voltages for long distance transmissionranges from 230kv and 500kv.

High-voltage transmission lines are quiterecognizable. They are normally made of huge

steel towers like this:

THE DISTRIBUTION SUBSTATIONS

At the end of the high-voltage transmission linein town or city, bulk power or delivery pointsubstation is connected. The power transformer

in this substation lowers the voltage tosubtransmission level, usually at 115,000volts

When electricity comes closer to where it is

used, its voltage is further reduced todistribution level (34,500 volts or less).


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Inside the distribution substation are otherelectrical devices such as breakers and switches

which function similarly to a houses protectiveelectrical system.

DISTRIBUTION LINES

From the distribution substation, severaldistribution lines go out to the streets to carry

the electricity to different places where theconsumers are located. Majority of the

distribution lines are installed overhead or on

poles and a few are built underground.

DISTRIBUTION TRANSFORMER

Since the voltage at the distribution line is still

high (34,500 volts), it must be reduced to auseable level, normally 220 volts, before it

reaches the consumer.

The voltage reduction is done through thedistribution transformer attached to a pole. This

transformer is the drum-shaped equipmentinstalled near the top of the pole. Connected to

this transformer are secondary lines that finally

bring the electricity to homes, offices, factoriesand other users.

What an unbelievable story!

It took all of that equipment to get power from

the Power Plant to the light in your bedroom.

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Fluorescent lamps can be found everywhere.

Let's find out how it works.
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The fluorescent lamp is basically a Sealed GlassTube, which contains some mercury and an

inert gas (like argon or neon).

The tube is also coated from the inside byphosphor powder.

On both ends of the tube are two electrodes,which are connected to an electrical circuit,

which is connected to an AC power supply.

When you turn the switch on, electricity fromthe two opposing electrodes changes some ofthe mercury from liquid to gas. As this is

happening, the excited mercury atoms bumpinto each other, releasing energy and light.

This Ultra Violet light released from the

excited mercury atoms can not be seen

by the naked eye, so you need the phosphorsto convert them to visible light.

This process takes less energy, and so makesthe fluorescent lamp more efficient, up to six

times more than yourregular light bulb.

There many new forms of fluorescent lamps and

one of the more popular ones is called theCompact Fluorescent Lamp or CFL's. It comes

in many shapes sometimes they even look likeregular light bulbs.

All that science inside a plain white tube.A pretty amazing Filipino invention


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The air conditioner is one appliance whichwe rely on during hot summer months. Think of

it as a refrigerating system for your room.

It uses the evaporation cycle process to lowertemperatures.

A pipe located at the back of the aircon containsa gas called refrigerant.

The compressor compresses the refrigerant andturns it into a warmer liquid. This liquid passesthru an expansion valve.

As the liquid refrigerant passes thru the

expansion valve, the liquid evaporates,

changing its state back to gas, lowering thetemperature.

This cold refrigerant, runs through a set of coilson the inner part of the aircon.

With the help of a blower fan, warm air frominside your room is sucked in, and cooled by the

coils. The cooled air is then blown out into yourroom.

Now here's an interesting fact. There are

actually 2 motors running your aircon. Thecompressor which consumes a lot of electricity

and the blower. The compressor is running 80%of the time, while the blower runs 100% of the

time.


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The refrigerator - it's more than just a boxwhich keeps your food

cold and fresh.

It is composed of 3 basic parts.

The compressor...

Heat exchanging pipes that can be found at theback part of the body...

And heat-exchanging pipes inside the insulated

box.

The Expansion Valve.

Just how do they work together?

First, the Compressor pressurizes the

Refrigerant gas and raises pressure andconsequently its temperature.


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Then, the compressed and hot Refrigerantflows through the back pipe, releasing heat.

This is the reason why the back part of yourrefrigerator is warm.

The gas continues to flow through the

Expansion Valve. When it flows through theexpansion valve, the liquid refrigerant is moved

from a high-pressure zone to a low-pressurezone, so it expands and evaporates.

The refrigerant then becomes cold.

The coils inside the refrigerator allow therefrigerant to absorb heat, making the inside

of the refrigerator cold, keeping your foodfresher for longer time.

The cycle repeats itself to maintain the cooltemperature inside the box.

Pretty amazing technology for such a commonappliance, right?

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A washing machine is made up of 3 parts:

First is a heavy motor that spins laundry.

The second part is a balancing system to keep it

in place, which is composed of a metal framethat holds the motor and concrete weight to

balance the washing machines movements...As well as three pulleys that counter balance

each other so that the machine does not shake.

Towards the bottom of the washing machine,

there is a damping system that are attached tothe washing machine frame via springs. This

system squeezes two pads against the blackmetal frame to absorb some of the force from

the vibrations.And the third and main part, which does all the

washing are two steel tubs composed of ...
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An outer tub, which seals in all the waterand is bolted to the body of the washer and ...

An inner tub, which holds the clothesand is perforated at the sides so thatwater can leave.

This inner tub is attached to the gearbox,which is attached to the motor. In the middle of

the inner tub is the agitator that keeps theclothes moving, to make it clean.

It is mainly this movement that makes yourclothes clean.

Simple yet efficient. Thats how your

mechanical lavandera works.

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A TV is made out of a vacuum tube...

...with heated filament cathode.

And coated with Phospor.

The majority of televisions today are

powered by a Cathode Ray Tube (CRT).The cathode ray tube is polar.

The positive end is called the "anode"

and the negative end is the "cathode".
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The cathode is a heated filament similar to alight bulb and the ray a stream of electrons that

naturally pour off a heated cathode into thevacuum.

The anode then attracts the electrons pouringoff the cathode through a tight, high-speedbeam.

This beam then hits the screen which is coatedwith phosphors that glow when struck by

the beam.

The beam is controlled by steering coils usingdifferent voltages, thus allowing the beam tohit any point on the screen.

In color TV's, there are 3 beams in red, green,

and blue which when mixed, can create

256-color images.

White color is produced by mixing all the 3beams in perfect proportion.

Black is produce simply by turning off all thebeam at the particular point or spot.

Sounds complicated? Not quite. It's simple, yet

entertaining

Electrical Injuries


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Electrical shocks due to the use of electrical equipment occur without warning andare usually serious. The average individual thinks of the hazards of electric shock in

terms of high voltage and does not always realize that it is primarily the current thatkills and not the voltage. Consequently, persons who work around low-voltage

equipment do not always have the same respect for it than they do for high voltageone. They do not realize that the governing factor is the relationship between the

voltage one is in contact with and the resistance of the circuit of which his body is apart. If this resistance is low, the voltage may be low and still be sufficient to kill.

Deaths from the ordinary 110-volt lighting circuit are frequent.

A person receives an electric shock whenever any part of his body becomes part of

an electric current. In such case, he/she is subject to injury in two (2) ways:1. From nerve shock, which, if great enough, will cause the stoppage of the lungs or

heart or both.2. From the heating effect of the current which may cause severe burns chiefly where

the current enters or leaves the body.The severity of electric shock is determined by:

1. The amount of current that flows through the body2. The path the current takes through the body

3. The length of time (duration) the victim is in the circuit

4. The type of electric energy involved5. The physical condition of the victim

The amount of current that flows through a person's body depends upon the

following:1. The voltage of the circuit with which a person is in contact

2. The insulating qualities of the place in which a person is located at that instant3. The resistance of his/her skin or clothing or both

4. The area of contact with the live conductor5. The pressure of contact with the live conductor

Causes of injuries from low voltages:1. Touching live (energized) parts, direct contact

2. Short circuit

3. Accidental ground, inadequate grounding4. Overload

Reaction of the body to electric shock1. Fatal shock

Fifty (50) to one hundred (100) milliamperes has been known to cause death,especially if the path of the current is through the heart.

One hundred (100) to two hundred (200) milliamperes, depending on length of time

(duration of exposure of the victim), causes certain death (due to ventricularfibrillation).

High currents of short duration do not always affect the heart seriously. After freeingthe person from electrical contact, start artificial respiration at once if breathing

stopped.2. "Freezing to the line"

Fifteen (15) to twenty (20) milliamperes will cause a painful shock and the control ofthe adjacent muscles is lost; the person cannot turn loose from the wire or

conductor.

Death will occur if the person is left in contact too long because the heart willcollapse or breathing will stop.

3. Sensation of shockOne (1) to eight (8) milliamperes is not painful and the person can free himself from

contact with the live wire or conductor of electricity.


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Eight (8) to fifteen (15) milliamperes is painful, but the person can free himself fromcontact with the energized wire or conductor. However, the hazard in this situation is

that the person may be injured by jumping or falling from heights, moving machinesor traffic.

What are microwaves?

Microwaves are a form of electromagnetic radiation. Microwaves fall into the radiofrequency band of electromagnetic radiation and should not be confused with x-rays,

which are far more powerful.What are the properties of microwaves?

Microwaves have three characteristics that make them suitable for cooking:they are reflected by metal

they pass through glass, paper, plastic, and similar materialsthey are absorbed by foods

How does a microwave oven work?Microwaves are produced inside the oven by electron tube called magnetron. The

microwaves bounce back and forth within the metal interior until they are absorbedby food. Microwaves cause the water molecules in food to vibrate, producing heat

that cooks the food.

ON SAFETYA microwave oven is actually one of the safest devices in your kitchen when used

correctly, according to Louis Bloomfield, physics professor of the University ofVirginia.

Myth: Radiation injuries can be incurred from microwave ovens.

Fact: According to the U.S. Food and Drug Administration (FDA), the known injuriesare those that could have happened with any oven or cooking appliance and not

radiation injuries. People might have been burned by the hot food, splatteringgrease, or steam from food cooked in a microwave oven.

Myth: Radiation from microwave ovens can harm people.

Fact: The safety standard enforced by the U.S. FDA for microwave ovens is set at 5milliwatts of microwave radiation per square centimeter or 2 inches from the oven

surface. This is far below the level known to harm people.

Myth: Microwave ovens are not safe to use since radiation may leak from them.Fact: The U.S. FDAs standard also ensures that microwave ovens meet the radiation

safety standard. This requires manufacturers to ensure interlock systems that stopmicrowave production in the oven the moment the latch is released or the door is

opened.ON NUTRITION
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Myth: Microwave cooking drastically reduces the nutritional value of food.Fact: Microwaved foods retain more vitamins and minerals than foods cooked by

other methods because they can cook more quickly and without adding wateraccording to FDA. The nutritional value of foods is only reduced when foods are

overheated in a microwave oven.ON HEALTH

Myth: Microwave energy can make food radioactive or contaminated.Fact: Microwave energy is changed into heat as soon as it is absorbed by food thus it

can not make food radioactive or contaminated.

Myth: Microwave radiation can cause burns, cataracts and temporary sterility.

Fact: Such injuries can only be caused by exposure to large amounts of microwaveradiation. The amount of radiation that causes such injuries is far greater than the

radiation caused by a leak from a microwave oven, according to the U.S. FDA.Myth: Electromagnetic emissions from microwave ovens could interfere with heart

pacemakers.Fact: Modern pacemakers are shielded against such interference as confirmed by the

Michigan State University Extension.ON ELECTRIC CONSUMPTION

Myth: Microwave cooking is expensive in terms of electric consumption.

Fact: According to FDA, microwave cooking can be more energy efficient thanconventional cooking because foods cook faster and the energy heats only the food,

not the oven compartment.

Remember, successful microwave cooking depends on understanding the capabilitiesas well as its benefits. If used correctly, microwave ovens offer a fast, cheap,

convenient and safe method of food preparation.

energy engg_meralco literature-01

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