bab 8 generation of electricity

8/13/2019 Bab 8 Generation of Electricity

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CHAPTER 8: GENERATION OF ELECTRICITY

Electrical energy for home and commercial use isproduced by machines called generators.

Generators convert mechanical energy to electricalenergy.

A generator consists of copper coils surrounded bymagnets.

Turbines are usually connected to the copper coil of thegenerator by a shaft.

When the turbines are turned, the spinning shaft willcause the copper coil to spin and electrical energy isproduced.


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3

Electricity is produced in

generators Generators require other

sources of energy

Conversion of mechanical

energy into electrical energy

Electromagnetic Induction

Turbine turns coils of wire

in a magnetic field toproduce a current


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Thermal Generator - nr• There are various type of

generator – Thermal generator

In a thermal power station, fossilfuels such as petroleum, coal and

natural gas are used to heat

water in a boiler to produce

steam under high pressure.


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Hydroelectric Generator - r

• The steam is used to turn

the turbines of a thermalgenerator.

• In a hydroelectric powerstation, water flowing at

high speed and pressureform the dam forces theturbines to rotate thegenerator to produceelectrical energy.


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Diesel Generator -nr

• In a diesel powerstation, a diesel motor is used toturn the coppercoil of a dieselgenerator. Dieselgenerators areusually used toproduce smallsupplies ofelectrical energy tosmall villages


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Alternative Sources of Energy

• Except for hydroelectric power stations, other

types of power stations use non-renewablesources of energy.

• 2. Two alternative sources of energy are:

• i. Biomass

• ii. Sun

• 3. Biomass refers to the mass of living things

in an area. The decomposition of the• remains and waste of living things by bacteria

produces a gas called methane. Methane

• can be used as a fuel.

• There are two ways to tap solar energy toproduce electrical energy.

• Solar cells/solar panel convert energy from thesun into electrical energy.


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Transformer

• A transformer is a devices used for raising orlowering the voltage of alternating current.

• A simple transformer consists of a soft ironcore with two coils of wire on each side ofthe core as shown below.

• There are two type of transformer; – A. the step-up transformer and

– B. the step-down transformer.

• A step-up transformer has more turns ofwire on the secondary coil than the primarycoil.

• A step-down transformer has less turns ofwire on the secondary coil than the primarycoil as shown below.

• The number of turns of wire in the primary

and secondary coils determines the outputvoltage.

• A step-up transformer has more turns ofwire on the secondary coil and so producesa higher voltage in the secondary coil.

• A step-down transformer has less turns ofwire on the secondary coil and so producesa lower voltage in the secondary coil.


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b. Step-Down transformer


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C t i th El t i l P


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Components in the Electrical Power

Transmission and Distribution System.

•

The components in the electricalpower transmission anddistribution system include:

– National Grid Network

– Transformer Stations

– Switch Zones

– Main Substation


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The Functions of the Components in the Electrical

Power Transmission and Distribution System.

• Each component in the electrical powertransmission and distribution system has itsspecific function.

• The Transformer Station has transformers tostep up or step down the voltage of electricalenergy.

• The Switch Zone allows the electrical energy tobe transmitted through the National Grid

Network.• The National Grid Network connects power

stations at different places together andtransmits electrical power to various placesthroughout the country. – Advantages

• Electrical energy can generated according to the timeneeded. Some power station can be shut down at

periods when energy need is low and reconnectedwhen energy need increases, this can save costs.

• If one of the power stations breaks down, its functioncan be taken over by another station in the networkwhile waiting for the damaged station to be repaired.This avoids the cessation of electricity supply.

Tryer 10

• The Main Substation has transformers that step

down the voltage of electrical power tosuitable value to be distributed to its branches.


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Plan Grid Facilities

Reliability

Load Growth

Interconnections

Operate

904 Substations (16 manned)890 Transmission Circuits

4,166 Distribution Circuits

Protect & Test

Automate

Construct & Maintain

16,945 Circuit Breakers

4,459 Transformers13,585 Circuit Miles

42,000 Relays

15 UPS Sites

4,000 Miles Communication

CircuitsAdministrative Contracts

Over 300 Grid Contracts

Construct & Maintain

43,776 Switches

670,496 Transformers1,448,794 Poles

94,854 Circuit Miles

317,820 Underground Structures

1,300,000 Trees

11,873 Cap Banks

760,000 Street Lights

Distribution

Plan Distribution Facilities

Reliability

Load Growth

Automation

Transmission/Substation


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Wiring system at home


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Wiring system at home


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Test


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Electrical Power Supply at Home

• The mains voltage channelled to homesfrom the substation is 240 V.

• Two types of electric currents, namelyDirect Current (DC) & Alternating Current(AC). DC is current that flows only onedirection (battery).

• Electrical current (Alternating Current) ischannelled to homes through cables. These

cables consist of two types of wires, whichare:

• a. The Live wire - this type ofwire carries current from the substation

• to home.

• b. The neutral wire - this type of

wire returns current from homes to the• substation.

Rumah kita biasanya AC


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Transmission Lines

Transmission lines:

500 kv to 161 kV

Subtransmission lines:

55 kV to 138 kV

Distribution lines:

33 kV down


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The wiring system in homes includes the:

1. Fuse Box

- Contains fuses that melt and break the flow of current

to protect Electrical circuits from overloading or fromshort circuit.

2. Mains switch

– Controls the electrical supply to all circuit in a home.

3. Circuit Breaker

- A circuit is broken in specific situations for example

when lightnings strike.

4. Live Wire – brown/BLACK

– this type of wire carries electrical current to a home.

5. Neutral Wire - blue

– this type of wire returns current to the substation. PMR2010

6. Earth Wire – green + yellow

–this type of wire carries leaked current to the Earth.

7. Electric Meter

- Measure the total amount of electrical energy used

in a home.


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Electrical Wiring System

• Generally, the electrical

wiring at our home is thesingle-phase wiring.

• The three-phase wiring isusually used in placeswhere the electrical energy

consumption is higher.• The electrical wiring system

at home consists of a fusebox, electric meter, mainswitch, circuit breaker, main

electrical panel, live wire,neutral wire and earth wire.

http://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phase_electric_power


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Generally, the electrical

wiring at our home is the

single-phase wiring.

The three-phase wiring is

usually used in places where

the electrical energy

consumption is higher.

http://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phase_electric_powerhttp://en.wikipedia.org/wiki/Three-phase_electric_power


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MCB


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ELCB

http://www.peopleelectric.com/AB.pdf


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3-pin Plug PMR 2010

• The colour of the live wire is brown, the

neutral wire is blue and the earth wire isyellow with green stripes.


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PERAK 12


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THE COST OF ELECTRICAL ENERGY USAGE


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Calculating the Amount of Current Flowing Through an

Electrical Appliance.

P

V I


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P

V I

E

P T

E (j) = P (kW) x T (h)

= 45/1000 x 5

= 0.225 kWh

= 0.225 kWh x RM0.20

= RM0.045


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Test


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THE FUNCTIONS OF FUSE AND EARTH WIRE.

• A fuse is a device used toprotect an electric circuit

against excessive current.• It consists of a wire that will

melt at a certain temperature.

• The wire is usually made of analloy of tin and lead.

• There are two main types offuses. – In a replaceable wire fuse, a

length of wire is attached tothe terminals

– The cartridge fuse, consists of awire enclosed in a cylindricaltube made of an insulatingmaterial as shown below.

•

• The rating of a fuse is the

maximum amount of currentthat can flow through the fusewithout the wire of the fusemelting.

• The rating of a fuse is alwaysindicated on the fuse.

• Common fuse ratings are 1 A, 2A, 3 A, 5 A, 10 A and 15 A.


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The Function of Fuses PMR 2010

• When a short circuitoccurs, there is lowresistance and a largeamount of currentflowing in the circuit.

• This may cause a fire anddamage to electrical

appliance. To preventthis, fuses are used.

• During a short circuit willcause the wire of thefuse to heat up and melt.The circuit then becomes

incomplete and currentstops flowing in thecircuit.

Determining the Suitable Rating of a


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Determining the Suitable Rating of aFuse for an Electrical Appliance.

• The rating of a fuse is the value of themaximum current that is allowed toflow through the fuse without causingthe wire of the fuse to melt.

• Fuses to be used in electricalappliances should have a rating of justslightly more than the current whichthe electrical appliances will useunder normal working condition.

• For example, a fuse of 3 A may beused for an electrical appliance thatoperates on a current of 2.5 A.

•


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Perak 2011


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Perak 2011


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PMR 2011


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PMR 2011


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PMR 2011


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Penutup

2. Tasbih Kifarah.

1. Baca Surah Al-`Ashr

bab 8 generation of electricity

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