WorksheetsPower Distribution and Earthing Systems
Total questions: 1
Worksheet time: 7mins
What is the initial voltage of electricity generated at power stations before it is stepped up for transmission?
132,000 volts AC
25,000 volts AC
400 volts AC
11,000 volts AC
To what higher voltage is electricity stepped up for transmission on the National Grid network?
400,000 volts AC
11,000 volts AC
230 volts AC
400 volts AC
Why is electricity transmitted at high voltages?
To increase the current
To increase voltage drop
To reduce the conductor size and cost
To increase the weight of conductors
What is the voltage level when electricity is transformed down at local substations for domestic use?
230 volts AC
11,000 volts AC
132,000 volts AC
400,000 volts AC
What does TNS stand for in UK domestic electrical installations?
Terra Neutral Separate
Terra Neutral System
Terra Neutral Single
Terra Neutral Secure
What is the maximum earth fault loop impedance for a TNS system?
1 ohm
200 ohms
0.8 ohms
0.35 ohms
What does TT system rely on for earth protection?
The physical earth
The outer sheathing of the supply cable
A separate earth conductor
A combined earth and neutral conductor
What is the maximum earth fault loop impedance for a TNCS system?
1 ohm
200 ohms
0.8 ohms
0.35 ohms
What additional protection is always provided in a TT system?
Circuit breaker
RCD protection
Fuse protection
Surge protector
Which of the following is NOT a property of the supply authority?
The meter
The fuse
The consumer unit
The supply cable
