Deck 1 Flashcards
Name the basic unit of electrical current.
Amp.
What is the instrument used to measure an electrical resistance?
Ohmmeter
What is used to measure electrical current?
Ammeter.
Name the pressure that forces electrons to flow through a circuit.
Voltage.
Voltage of a standard car battery.
12.6 Volts
What is the voltage at a domestic socket outlet?
230 Volts
What is the basic unit of resistance?
Ohms.
Name the two electrical conductors used in cables.
- Copper
2. Aluminium
Out of Copper and Aluminium, which has the greater current carrying capacity?
Copper.
What is the minimum amount of amps required to be fatal from an electric shock?
30 milliamperes (mA)
Name the electrical insulators used within PILC cables.
Belt Papers
Impregnated Papers
Name the electrical insulators in modern cables.
PVC Insulation
Xple Insulation
What does an electrical insulators do?
Protection from live metal work and conductors.
What is the national standard for phasing on LV?
1 2 3
Red Yellow Blue
Brown Black Gray
What do you use to check and confirm the LV network phasing at a substation?
Phase Rotation Meter.
What is the phasing for HV networks? 11kv & 20kv.
11kv = 1 2 3
20kv = 3 2 1
What does PME mean?
Protective Multiple Earth.
Can a neutral in an electrical system carry current?
Yes.
Why is the neutral in a three-phase cable the same size or smaller than the phase?
Because it doesn’t carry the same amount of load that the phases do.
Scenario:
PILC cable with no phase numbers and only faded colours, how do you determine the neutral core?
Phase check with the test lamps, searching for the core that gives no light when connected to the lead earth.
When making a new cable live what tests do you carry out beforehand?
- continuity test
- insulation resistance test
What is the most important item in a cable pot end and what does it do?
The earth.
Provides a return path for a fault current.
What is a PME system?
A earthing system that is combined with a neutral and uses multiple earth electrodes.
What is a neutral?
The return path for the current, goes back to the star point of the transformer LV board. Exists to complete the circuit allowing the current to flow.
