switchgear and protection MCQs – Page 5

Practise focused switchgear and protection questions with marked answers for exam preparation and subject revision.

switchgear and protection Mcqs
81. The information to the circuit breaker under fault conditions is provided by____________?
comments icon0

A. all of the above

B. relay

C. rewirable fuse

D. H.R.C. only

82. The delay fuses are used for the protection of ___________?
comments icon0

A. fluorescent lamps

B. motors

C. light circuits

D. power outlet circuits

83. A fuse in a motor circuit provides protection against__________?
comments icon0

A. overload

B. open circuit, short-circuit and overload

C. none of the above

D. short-circuit and overload
84. Over voltage protection is recommended for______________?
comments icon0

A. none of the above

B. all of the above

C. gas turbine generators

D. steam turbine generators

E. hydro-electric generators

85. Air blast circuit breaker is used for_____________?
comments icon0

A. over currents

B. short duty

C. intermittant duty

D. repeated duty
86. The fuse rating is expressed in terms of_____________?
comments icon0

A. voltage

B. kVA

C. VAR

D. current
87. relay is preferred for phase fault on short transmission line?
comments icon0
A. Reactance

B. None of the above

C. Induction type

D. Impedance

88. relays are used for phase faults on long line?
comments icon0

A. Reactance

B. Impedance

C. None of the above

D. Either of the above

89. A balanced 3-phase system consists of_______________?
comments icon0

A. zero, negative and positive sequence currents

B. zero sequence currents only

C. positive sequence currents only

D. negative and zero sequence currents

90. Overfluxing protection is recommended for_____________?
comments icon0
A. generator transformer of the power plant

B. station transformer of the power plant

C. distribution transformer

D. auto-transformer of the power plant

91. A fuse is never inserted in____________?
comments icon0

A. phase dine

B. neutral wire

C. positive of D.C. circuit

D. negative of D.C. circuit

92. Interruption of large currents by relay requires______________?
comments icon0

A. wide separation of the opened contacts

B. all of the above

C. high speed opening of contacts

D. arc suppressing blow out coils

93. The relay with inverse time characteristic will operate within____________?
comments icon0

A. none of the above

B. 5 to 20 sec

C. 5 to 10 sec

D. 1.5 sec

E. 20 to 30 sec

94. transmission line has reflection coefficient as one?
comments icon0
A. Open circuit

B. None of the above

C. Long

D. Short-circuit

95. Overheating of relay contacts or contact born out is due to_______________?
comments icon0
A. all of the above

B. foreign matter on the contact surface

C. slow making and breaking of load circuit contacts

D. too low contact pressure

96. The voltage appearing across the contacts after opening of the circuit breaker is called__________voltage
comments icon0
A. recovery

B. none of the above

C. surge

D. arc

E. operating

97. Magnetic circuit breaker has ___________ trip action
comments icon0

A. delayed

B. instantaneous

C. both of the above

D. none of the above

98. The fuse wire, in D.C. circuits, is inserted in____________?
comments icon0

A. negative circuit only

B. positive circuit only

C. both (A) and (B)

D. either (A) or (B)

99. Large internal faults are protected by_______________?
comments icon0

A. earth fault and positive sequence relays

B. horn gaps and temperature relays

C. mho and ohm relays

D. merz price percentage differential protection
100. The material used for fuse must have_____________?
comments icon0

A. low melting point and any specific resistance

B. low melting point and -low specific resistance

C. low melting point and high specific resistance

D. high melting point and low specific resistance