Switchgear protections

11. ________ relay is preferred for phase fault on short transmission line.

Induction type
Reactance
Impedance
None of the above

Detailed Solution________ relay is preferred for phase fault on short transmission line.

12. The information to the circuit breaker under fault conditions is provided by

relay
rewirable fuse
H.R.'only
all of the above

Detailed SolutionThe information to the circuit breaker under fault conditions is provided by

13. A switchgear is device used for

Interrupting an electrical circuit
Switching an electrical circuit
Switching and controlling an electrical circuit
Switching, controlling and protecting the electrical circuit and equipment

Detailed SolutionA switchgear is device used for

14. For which of the following ratings of the transformer differential protection is recommended ?

above 30 kV
equal to and above 5 MVA
equal to and above 25 MVA
none of the above

Detailed SolutionFor which of the following ratings of the transformer differential protection is recommended ?

15. Which of the following is the least expensive protection for overcurrent is low voltage system ?

Rewireable fuse
Isolator
Oil circuit breaker
Air break circuit breaker E. None of the above

Detailed SolutionWhich of the following is the least expensive protection for overcurrent is low voltage system ?

16. The power loss is an important factor for the design of

transmission line
motor
generator
feeder

Detailed SolutionThe power loss is an important factor for the design of

17. The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to

lubricate the contacts
insulate the contacts from switch body
extinguish the arc
all of the above E. none of the above

Detailed SolutionThe contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to

18. Bus coupler is very essential in arrangement

single bus
double bus, double breaker
main and transfer bus
all of the above

Detailed SolutionBus coupler is very essential in arrangement

19. A fuse in a motor circuit provides protection against

overload
short-circuit and overload
open circuit, short-circuit and overload
none of the above

Detailed SolutionA fuse in a motor circuit provides protection against

20. To protect most of the electrical equipment handling low power, the types of relays used are

Thermocouple
Electronic and bimetallic
Both (A) and (B)
None of the above

Detailed SolutionTo protect most of the electrical equipment handling low power, the types of relays used are

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