EWRB THEORY EXAM PREP STUDY GUIDE 100% PASS QUESTIONS WITH DETAILED ANSWERS
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Course
EWRB
Institution
EWRB
State the permissible test result for an insulation resistance test for the electrical installation with ALL the permanently-connected electrical equipment DISCONNECTED - ANS 1 Mega Ohm
State the permissible test result for an insulation resistance test for the electrical installation with AL...
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PASS QUESTIONS WITH
DETAILED ANSWERS | A+
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, State the permissible test result for an insulation resistance test for the electrical installation with
ALL the permanently-connected electrical equipment DISCONNECTED - ANS 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 - ANS 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. - ANS - The power factor of the
motor will be poor
- The motor will be less efficient
- running costs rise
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A three-phase induction motor has been OPERATING NORMALLY ON FULL-LOAD. The motor
starts to overheat even though it is drawing the normal full load current.
State ONE reason why this situation would occur - ANS - The motor ventilation is restricted in
some manner
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- 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
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to service. - ANS Clamped around the protective earthing conductor and 5mA
Explain what is meant by the term INVERSE TIME-CURRENT CHARACTERISTIC in relation to
protective devices - ANS as current through the protective device increases, the time taken to
operate decreases
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State TWO components that are typically used to smooth the d.c output of a rectifier - ANS -
Capacitors
- Inductors
- Resistors
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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 - ANS 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? - ANS 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 - ANS A bi-polar junction
transistor
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