PMR Science Chapter 8 Generation of Electricity

1. Generation of Electricity
CHAPTER 8

2. Generator
 Electrical energy is produced by using a
generator in the power station.
 Also called : Alternator or dynamo.
 Generators convert mechanical energy into
electrical energy.

3. Thermal Generator

4. National
Electrical
Fossil fuel Grid
Energy
Network
Heat
Generator Consumers
energy
Steam
Steam
turbine

5. Hydroelectric Power Plant

6. Supply Chain of Water
High
High
Water Potential Reservoir
Position
Energy
High Pass
Generator Rotation Kinetic through
Energy Turbines
National
Grid Consumers
Network

7. Hydroelectric Generator

8. Hydroelectric Generator

9. Hydroelectric Generator

10. Diesel Generator

11. Diesel Generator
Diesel Rotation Generator
Small Small
Town / Village Current

12. Diesel generator

13. Gas Turbine Generator

15. Gas turbine generator
Compressor
Air Gas chamber Mix with
• Filter Natural gas
• Compress
Gas expand CO2 + H2O Ignited by Combustion
produced Spark Plugs chamber
Rotation Generator Electrical National Grid
energy Network

16. Nuclear Power Plant

17. Nuclear Power Plant
Uranium Nuclear Nuclear
Heat energy
Plutonium reactor fission
Rotate
Generator Steam Boiler
turbines
Electrical National Grid
Consumers
energy Network

18. Nuclear Power Plant

19. Alternative energy

20. Wind Turbine Generator

21. Cogeneration of energy

22. Transformers
 Function: To increase or decrease the voltage
of an alternating current
 Alternating current flows in two direction
 From the source of electricity
 Back to the source of electricity
 Generated by generators

23. Transformers are used to change the voltage of
alternating current.
A basic transformer consists of two sets of
insulated coil windings on opposite sides of a soft
coil.
The core is constructed of many layers of thin
iron called laminations.

24. Structure of transformer
More coils – Higher voltage
- Brighter light bulb

25. b. The primary coil is the wire coil that
connected to the input voltage.
c. The secondary coil is the wire coil that
connected to the electrical load ( output
voltage).

26. The output voltage produced in the secondary
coil depends on
a. the input voltage
b. The number of turns of the primary coil and
secondary coil.

27. Step up Transformer

28. Step Up Transformer

29. Step down Transformer

30. Calculation

31. Electricity Transmission and
Distribution System

32. Electricity Transmission and
Distribution System
Power station Transformer Switch zone National Grid
station (132 000 V) Network
(11 000V) (132 000 V) (132 000 V)
(275 kV)
(500kV)
Substation
• City (416 V) Substation Main substation
• House (240 V) (11 000 V) (33 000 V)

33. Electricity Transmission and
Distribution System

34. Transmission over a long distance
 High voltage
 Low current
 Reduce power loss

35. Electricity Transmission and
Distribution System

36. Electricity Transmission and
Distribution System

37. Location of Transformer
 Step Up Transformer
 Nearby Power Station
 Before being distributed to National Grid Network
 Step down Transformer
 Main substation
 Branch substation
 Heavy industries – 33kV
 Small industries – 11 kV
 City & Commercial – 450V
 Residential area – 240V

38. Electricity Transmission and
Distribution System

39. Electrical Supply and Wiring
Systems at Home

40. Electrical Supply and Wiring
Systems at Home
Main fuse Electric meter Main Switch
Lighting and Circuit
Fuse box
power circuits breaker

41. Wiring System at Home
 Live Wire (Brown)
 Neutral Wire (Blue)
 240V
Live Wire
Electrical
Appliances
Neutral
Wire

42. Earth Wire
 Safety device
 Direct excess current
to an underground
copper plate

43. Electric Meter and Main Fuse
 Electric meter
measures the amount
of current supplied to
the house
 Main fuse – melt when
excessive current flows
through
 Break down circuit
 Safety device

44. Main Switch and Circuit Breaker
 Controls the electric  Cuts off the flow of
energy from the mains electric current under
supply to the abnormal condition
appliances.  Short circuit of leakages

45. Distribution Lines of Electricity
Single Phase Three phase
Residential Energy from
Low Voltage High Voltage Industrial Area
Area (240V) Substations

48. 3-pin Plug

50. 2-pin Plug

51. Electric power
 Measure of the amount
of electrical energy
used per unit time
 Unit: Watt
 1 Watt = 1 Joule per
second

52. Oven = 800 Watt
Voltage supplied = 240V
Current = ?

53. Cost of Electricity
Cost of Electricity = kW x Hour x Price per unit

54. Fuse and Earth Wire

55. Rating : 1A, 2A, 5A, 10A, 13A Fuse
Gets heated up and melts
When the current flowing
through it is higher than its rating

56. Determination of Fuse Rating
Voltage Power Current Fuse
Rating
240V 120W
240V 600W

57. Fuse
 Prevents current
exceeding its rating
from flowing through
the cable and wires in
the household
circuits.

58. Earth Wire
 Low resistance
 Connects the metal
casings of electrical
appliances
 Directly to the ground.