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Ewrb Theory Exam Prep Questions And Answers With Verified Solutions Already Passed!!!
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Ewrb Theory Exam Prep Questions And Answers With Verified Solutions Already Passed!!!
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Ewrb Theory Exam Prep Questions AndAnswers With Verified Solutions Already
Passed!!!
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.
State TWO factors that determine the severity of electric shock upon the human
body. - ANSWER✔✔ANY TWO:
- Voltage Applied
- Shock Current Level
- Contact Duration
- Skin Dryness
- Current Path
You have carried out a test on a low voltage final subcircuit in an electrical
installation, the result value was 20MΩ. What type of test has been carried out? -
ANSWER✔✔Insulation Resistance Test
State the main reason why interlocks are used in a star/delta starter. -
ANSWER✔✔To prevent the star and delta contractors closing simultaneously -
and causing a short circuit.
Calculate the power factor of a small three-phase printing factory with mainly
motor loading. Metering instruments have recorded the following:
Power = 30000W
Voltage = 406V
Current = 57A per phase - ANSWER✔✔0.748
pf = P/V×I×√3
Define the term CUT OFF TIME as it refers to HRC fuses. - ANSWER✔✔ANY
ONE:
- Pre-arcing Time: Time taken to melt the fuse elements.
- Arcing Time: The time taken between the initiation of the arc, and the arc
extinguishing.
- Cut Off Current: The fault current that will cause the fuse to blow.
- Total Clearing Time: The time it takes to interrupt the flow of current and
extinguish the flame.
State the purpose of the slip-rings on a wound rotor induction motor (or slip-ring
motor). - ANSWER✔✔To connect the external resistance to the wound motor.
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