Top 150+ Solved Switch Gear and Protection MCQ Questions Answer
Q. A balanced 3-phase system consists of
a. zero sequence currents only
b. positive sequence currents only
c. negative and zero sequence currents
d. zero, negative and positive sequence currents
Q. In a single bus-bar system there will be complete shut down when
a. fault occurs on the bus itself
b. fault occurs on neutral line
c. two or more faults occur simultaneously
d. fault occurs with respect to earthing
Q. Which device is used for protection of equipment from from damagecaused by overload or short circuit?
a. CVT
b. Circuit Breaker
c. Current Transformer
d. Lighting Arrester
Q. Isolator in substation is open under ------------- condition?
a. No load
b. Short Circuit
c. Full Load
d. Any of the above
Q. Earthling switch is used for
a. measuring of safety voltage
b. protection of equipment from ground faults
c. discharging residual energies
d. all of the above
Q. If the time of operating of a relay for unity TMS is 10secs., the time ofoperation for 0.5 TMS will be
a. 20 secs.
b. 5 secs.
c. 10 secs.
d. None of the above
Q. A fault is more severe from the view point of RRRV if is a
a. Short line fault.
b. Medium length line fault.
c. Long line fault.
d. None of these.
Q. A reactance relay is
a. Voltage restrained directional relay.
b. Directional restrained over-current relay.
c. Voltage restrained over-current relay.
d. None of the above.
Q. For measuring positive, negative and zero sequence voltages in asystem, the reference is taken as
a. Neutral of the system only.
b. Ground only.
c. For zero sequence neutral and for positive and negative the ground.
d. None of the above.
Q. Positive, negative and zero sequence impedances of a solidly grounded system under steady state condition always follow the relations
a. Z4>Z2>Z0
b. Z2>Z4>Z0
c. Z0>Z4>Z2
d. None of the above
Q. Phase comparators in case of static relays and electro-mechanical relaysnormally are
a. Sine and cosine comparators respectively
b. Cosine and sine comparators respectively.
c. Both are cosine comparators.
d. Both are sing comparators.
Q. For reducing tower footing resistance it is better to use
a. Chemical and ground rods only.
b. Chemical and counterpoise only.
c. Ground rod and counterpoise only.
d. Chemical, ground rods and counterpoise.
Q. Rate of rise of restriking voltage depends
a. Type of circuit breaker.
b. Inductance of the system only.
c. Capacitance of the system only.
d. Inductance and capacitance of the system
Q. What is the purpose of back up protection?
a. To increase the speed
b. To increase the reach
c. To leave no blind spot
d. To guard against failure of primary
Q. What is the actuating quantity for the relays?
a. Magnitude
b. Frequency
c. Phase angle
d. All of these