Power system MCQ #9

Power system MCQ 133 to 136:

133) the primary function of fuse is

      (a) protect the line

      (b) prevent excessive currents from flow through the circuit

      (c) open the circuit

      (d) protect the appliances

134) A circuit breaker normally operates

      (a) when the power is to be supplied

      (b) when the switch is to be put on

      (c) when the line is to be tested

      (d) whenever fault occurs in the line

135) Arcing voltage is least in case of

      (a) copper

      (b) carbon

      (c) tungsten

      (d) silver

136) which of the following circuit breaker has lowest operating voltage?

      (a) air-blast

      (b) air-break

      (c) sf6 gas

      (d) minimum oil

ANSWER: | 133-b | 134-d | 135-d | 136-b |

Power system MCQ 137 to 140:

137) the restriking voltage is measured in

      (a) RMS value

      (b) instantaneous value

      (c) peak value

      (d) average value

138) In a circuit breaker the current that exist at the instant of contact separation is called _________

      (a) restriking current

      (b) arc current

      (c) breaking current

      (d) recovery current

139) which of the following circuit breaker is generally used in railway electrification?

      (a) air-blast circuit breaker

      (b) bulk oil circuit breaker

      (c) minimum oil circuit breaker

      (d) sff6 circuit breaker

140) which of the following circuit breaker has high reliability and negligible maintenance?

      (a) air blast

      (b) oil

      (c) sf6

      (d) vacuum

ANSWER: | 137-c | 138-d | 138-a | 140-c |

Power system MCQ 141 to 144:

141) Inverse time over current relay is used for the protection of

      (a) transformer

      (b) feeder

      (c) alternator

      (d) both a and b

142) An isolator is installed

      (a) usually on both sides of a circuit breaker

      (b) to isolate one portion of the circuit from another

      (c) as a substitute for a circuit breaker

      (d) both a and b

143) Protective relays are designed to respond to

      (a) resistance, reactance and impedance

      (b) temperature

      (c) light intensity

      (d) all of the above

144) The actuating quantity for the relay may be

      (a) frequency

      (b) magnitude

      (c) phase angle

      (d) any of above

ANSWER: | 141-d | 142-d | 143-d | 144-d |