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ELECTRICAL THEORY EWRB EXAM (2024) QUESTIONS WITH COMPLETE ANSWERS!!
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ELECTRICAL THEORY EWRB EXAM (2024) QUESTIONS WITH COMPLETE ANSWERS!!
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ELECTRICAL THEORYEWRB EXAM (2024)
QUESTIONS WITH
COMPLETE ANSWERS!!
EWRB
Evatee 10/5/24 EWRB
,ELECTRICAL THEORY EWRB EXAM (2024)
QUESTIONS WITH COMPLETE ANSWERS!!
State the permissible test result for an insulation resistance test for the
electrical installation with ALL the permanently-connected electrical equipment
DISCONNECTED Answer - 1 Mega Ohm
State the permissible test result for an insulation resistance test for the
electrical installation with ALL the permanently-connected electrical equipment
CONNECTED Answer - 0.01 Mega Ohms
A three-phase induction motor normally runs on full-load. State ONE reason
why this motor should not be run LIGHTLY LOADED when it runs on full load.
Answer - - The power factor of the motor will be poor
- The motor will be less efficient
- running costs rise
A three-phase induction motor has been OPERATING NORMALLY ON FULL-
LOAD. The motor starts to over-heat even though it is drawing the normal full
load current.
State ONE reason why this situation would occur Answer - - The motor
ventilation is restricted in some manner
- The cooling fan has become detached from the motor shaft
A clip-on ammeter is being used to test the integrity of the insulation of a
repaired Class I electrical appliance, while the appliance is live. Where on the
appliance would the clip-on ammeter be used? Also state the maximum test
, result that would allow the appliance to return to service. Answer - Clamped
around the protective earthing conductor and 5mA
Explain what is meant by the term INVERSE TIME-CURRENT CHARACTERISTIC in
relation to protective devices Answer - as current through the protective
device increases, the time taken to operate decreases
State TWO components that are typically used to smooth the d.c output of a
rectifier Answer - - Capacitors
- Inductors
- Resistors
The output circuit of an autotransformer MUST BE insulated for the highest
input or output voltage of the autotransformer. State ONE reason for this
requirement Answer - An auto transformer can fail in such a way so the
primary voltage appears across the secondary
An isolator for 230V electrical equipment has been replaced. During the work
the phase (active) and neutral were accidentally transposed at the supply side
of the isolating switch.
What potential danger would this transposition create? Answer - The internal
circuitry of the electrical equipment would be live when the isolating switch is
in the OFF position.
What to the initials BJT mean when applied to semiconductors Answer - A bi-
polar junction transistor
State the function of a transducer Answer - A device that changes energy from
one form to another
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