EWRB Theory Exam Prep QUESTIONS & ANSWERS(RATED A)
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Course
EWRB
Institution
EWRB
ANSWERS(RATED A)
When carrying out testing on a low voltage electric
What is the minimum value of the permitted test result for the insulation resistance test of a three-phase, 400V, mains cable? - ANSWER 1MΩ
al installation, which document details the tests and checks required to be carried ...
EWRB Theory Exam Prep QUESTIONS &
ANSWERS(RATED A)
What is the minimum value of the permitted test result for the insulation resistance test of a three-
phase, 400V, mains cable? - ANSWER 1MΩ
When carrying out testing on a low voltage electrical installation, which document details the tests and
checks required to be carried out? - ANSWER AS/NZS 3000
What is the minimum or maximum test result value you would consider acceptable for an Earth
Continuity test? - ANSWER 1Ω or less
State TWO types of electrical protection provided by a RCBO. - ANSWER ANY TWO:
- Earth Leakage
- Overload
- Short Circuit
If the voltage and current are known, what TWO other factors are required to calculate the power
consumed by a three-phase motor? - ANSWER √3 & Power Factor
What type of single-phase motor can be reversed by reversing the connections to the run winding? -
ANSWER ANY ONE:
- Split-Phase Motor
- Capacitor Start Motor
- Cap-Start, Cap-Run Motor
What type of single-phase motor can be reversed by reversing the connections to the armature brushes?
- ANSWER ANY ONE:
- Universal Motor
, - Series Motor
State ONE reason why the metal frame of a Class 1 electrical appliance is earthed. - ANSWER ANY ONE:
- To ensure the operation of a protective device under fault conditions.
- To keep the frame of the appliance at earth potential under fault conditions.
Calculate the fault current if a short circuit occurs on a 230V final subcircuit with an earth loop
impedance test result of 0.32Ω. - ANSWER 718.75A
MEN switchboards have characteristics that are NOT FOUND on a distribution board. Name TWO of
those characteristics. - ANSWER ANY TWO:
A MEN switchboard:
- Has a MEN link between the neutral and earth busbars.
- Has a connection to earth via an earthing lead to an earth electrode.
- Is electrically closest to the point of supply.
- Can supply to another MEN switchboard.
Why do three-phase induction motors run smoother and quieter than single-phase induction motors? -
ANSWER They have a constant rotating magnetic field.
State TWO reasons for using reduced voltage starting for a three-phase induction motor. - ANSWER ANY
TWO:
- Reduced starting current.
- Reducing voltage fluctuation/surges.
- Limiting mechanical shock.
What is the permitted protective earthing conductor test result for a test between the earth pin of an
appliance supply plug and the earth led accessible metal? - ANSWER 1Ω Max
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