Protective Relay MCQ

1. Which of the following is not a kind of relay on the basis of constructional feature

  1. Moving iron type
  2. Static
  3. Induction
  4. Current

Answer. d

2. Restoring force in an electromagnetic relay is produced by

  1. Magnet
  2. Spring
  3. Actuator
  4. Beam

Answer. b

3. An impedance relay is a ______

  1. Directional restrained over current relay
  2. Voltage restrained over current relay
  3. Directional restrained over voltage relay
  4. Voltage restrained directional relay

Answer. b

4. Programmable logical controllers are the devices that were invented basically to replace

  1. Switches
  2. Circuit breakers
  3. Relays
  4. None of the above

Answer. c

5. Pilot relaying schemes are used for the protection of

  1. Bus bars
  2. Transformer
  3. Instrument transformer
  4. Transmission line

Answer. d

6. Mho relay is

  1. Current restrained current relay
  2. Voltage restrained directional relay
  3. Current retrained directional relay
  4. Voltage restrained current relay

Answer. b

7. By burden on the relay, we generally mean

  1. Current rating of relay
  2. Voltage rating of relay
  3. Volt-ampere rating of relay
  4. Watt rating of relay

Answer. c

8. Earth fault relays are

  1. Directional relays
  2. Non-directional relays
  3. Short operate time relays
  4. Long operate time relays
Answer. b

9. A relay performs the function of

  1. Fault isolation
  2. Fault detection
  3. Fault prevention
  4. All the above
Answer. b

10. Buchholz’s relays are

  1. Installed inside the breaker
  2. Located on top of conservator pump
  3. Connected in pipe connecting transformer and conservator
  4. Part of circuit breaker installed near transformer
Answer. b

11. The following statements associated with buchholtz relays is not true

  1. It is a gas actuated device
  2. It is a current operative device
  3. It is placed between the transformer tank and the conservator
  4. It causes alarm for minor fault and tripping for major fault
Answer. b

12. Differential relays are used to protect the equipment

  1. Internal faults
  2. Reverse current
  3. Over current
  4. Over voltage
Answer. a

13. In earth breaker circuit uses

  1. Polarized relay
  2. Reed relay
  3. Latching relay
  4. Machine tool relay
Answer. c

14. A relay is

  1. A mechanical switch
  2. An electronic switch
  3. An electomechanical switch
  4. None of these
Answer. c

15. Which relay is used for protection of feeders?

  1. MHO relay
  2. Translay relay
  3. Merz price protection
  4. Buchhloz relay
Answer. b

16. Impedance relay can be used for

  1. Earth fault only
  2. Phase fault only
  3. Both earth and phase fault
  4. None of these
Answer. c

17. A relay with inherent directional characteristic

  1. Mho relay
  2. Impedance relay
  3. Reactance relay
  4. Differential relay
Answer. a

18. How many relays are used to detect the interphase fault of three-phase systems?

  1. One
  2. Two
  3. Three
  4. Six
Answer. c

19. Relay using induction disk principle operate

  1. Only on D.C.
  2. Only on A.C.
  3. Either D.C. and A.C.
  4. None of these
Answer. b

20. Buchholz relay is

  1. Gas actuated
  2. Current actuated
  3. Water actuated
  4. Voltage actuated
Answer. a

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