1. IDMT relays are used to protect the power transformers against
(a) external short-circuits.
(b) overloads.
(c) internal short-circuits.
(d) external short-circuits and overloads. Answer
2. Which of the following relay is used to detect and protect internal fault of a transformer?
(a) Differential relay.
(b) Bucholoz relay.
(c) IDMT relay.
(d) Directional relay. Answer
3. Which of the following relay is used for the generator phase to phase winding protection?
(a) Differential relay.
(b) Mho relay.
(c) Distance relay.
(d) Voltage balance relay. Answer
4. Which of the following relay is used for anti-motoring Protection Scheme?
(a) Reactance relay.
(b) Reverse power relay.
(c) Differential relay.
(d) Offset mho relay. Answer
5. Resistance switching in normally employed in
(a) bulk oil breakers.
(b) minimum oil breakers.
(c) air blast circuit breaker.
(d) SF6 circuit breaker Answer
6. In overhead system, the relay used for feeder protection is
(a) under-voltage relay.
(b) IDMT relay.
(c) Translay relay.
(d) thermal relay. Answer
7. The arc voltage in a circuit breaker is
(a) in the phase with arc current..
(b) lagging the arc current by 90°.
(c) leading the arc current by 90°.
(d) lagging the arc current by 180°. Answer
8. What is the reactive power in AC operation?
(a) Real power × sinφ.
(b) Apparent power × sinφ.
(c) Real power × cosφ.
(d) Apparent power × cosφ. Answer
9. The purpose of using series capacitor in a transmission lines is to
(a) reduce inductance.
(b) reduce line losses.
(c) compensate voltage drop.
(d) improve power factor. Answer
10. Which of the following circuit breaker is design for the least operating voltage?
(a) Vacuum circuit breaker.
(b) Air circuit breaker.
(c) SF6 circuit breaker.
(d) Oil circuit breaker. Answer
11. Which of the following circuit breaker is design for the highest operating voltage?
(a) Vacuum circuit breaker.
(b) Air blast circuit breaker.
(c) SF6 circuit breaker.
(d) Oil circuit breaker. Answer
12. Which circuit breaker has high reliability and negligible maintenance?
(a) Air blast circuit breaker.
(b) Oil circuit breaker.
(c) SF6 circuit breaker.
(d) Vacuum circuit breaker. Answer
13. The rating of a circuit breaker is usually determine on the basis of
(a) symmetrical fault.
(b) unsymmetrical fault.
(c) line to line fault.
(d) internal fault. Answer
14. Chimney effect occurs in air blast circuit breaker
(a) air blast circuit breaker.
(b) SF6 circuit breaker.
(c) vacuum circuit breaker.
(d) oil circuit breaker. Answer
15. The arc voltage in an AC circuit breaker is
(a) in phase opposition with the arc current.
(b) in phase with the arc current.
(c) lag arc current by 90°.
(d) lead arc current by 90°. Answer