MCQs on Switchgear and Protection

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1. which of the following fault result in symmetrical fault
(a) single phase to earth.
(b) all phase to earth.
(c) Phase to Phase.
(d) two Phase to earth. 

2. Electrical Switchgear is consider as low voltage Switchgear if it is rated upto
(a) 400 V.
(b) 1 kV.
(c) 11 kV.
(d) 33kV. 

3. Under normal condition, the voltage across a lighting arrestor is
(a) zero.
(b) very small.
(c) equal to phase voltage.
(d) equal to line voltage. 

4. The most dangerous fault in an alternator is failure of
(a) prime mover.
(b) failure of field.
(c) stator winding fault.
(d) unbalanced loading.   

5. Generally, the circuit breakers are rated  term of
(a) volt-ampere.
(b) current.
(c) voltage.
(d) VAR. 

6. Which device is used to protect the power system against traveling waves?
(a) capacitor.
(b) earth wire.
(c) surge diverter.
(d) earthing screen. 

7. In the electric system, Resonance may result in
(a) zero voltage.
(b) high voltage.
(c) low voltage.
(d) high current.   

8. A device which is used to protect an electric circuit from damage caused by over load or short circuit is
(a) Wave trapper.
(b) CVT.
(c) circuit breaker.
(d) lighting arrester.   

9. Main purpose of oil in oil circuit breaker is to
(a) provide insulation.
(b) provide cooling of contacts.
(c) quenching arc.
(d) none of the above.   

10. A thermal protection switch provides protection against
(a) overload.
(b) temperature.
(c) short circuit.
(d) over-voltage. 

11. Which of the following relay is preferred for grounding fault?
(a) Differential relay.
(b) Impedance relay.
(c) IDMT relay.
(d) reactance relay. 

12. The best location for use a booster transformer in a transmission line is
(a) at the sending end.
(b) at the receiving end.
(c) at the intermediate point.
(d) anywhere in the line.   

13. In overhead system, the transmission voltage can be controlled by
(a) excitation control.
(b) using induction regulator.
(c) reactive VAR injection method.
(d) Any of the above. 

14. Arcing voltage will be the least in case of
(a) carbon.
(b) silver.
(c) copper.
(d) tungsten. 

15. An lighting arrester behave like a
(a) non-linear resistance.
(b) linear resistance.
(c) variable resistance.
(d) none of the above. 

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