Top 250+ Solved Testing and Commissioning of Electrical Equipment’s MCQ Questions Answer
Q. Reactance relay is normally used for protection against
a. Earth fault only
b. Phase fault only
c. Both earth and phase faults
d. None of the above
Q. The operating characteristics of the reactance relay in the complex impedanceplane is a
a. Circle with its origin at the centre of the R-X plane
b. Circle passing through the origin
c. Straight line passing through the origin
d. Straight line parallel to the X axis
Q. A reactance relay is
a. Voltage restrained overcurrent relay
b. Voltage restrained directional relay
c. Directional restrained overcurrent relay
d. Directional restrained over voltage relay
Q. Reactance relays are used for phase fault in.......line
a. Short
b. Medium
c. Long
d. All of the above
Q. A differential relay response to
a. Algebraic difference of two or more similar electrical quantities
b. Phasor difference of two or more similar electrical quantities
c. Algebraic difference between two currents
d. Algebraic difference between two voltages
Q. Differential relays are used for protection of
a. Feeders
b. Alternators
c. Transformers
d. All of the above
Q. Differential relays are used for protection of equipments against
a. Internal faults
b. Over current
c. Reverse current
d. Reverse power
Q. In a biased differential relay the bias is defined as a ratio of
a. Number of turns of restraining and operating coil
b. Operating coil current and restraining coil current
c. Fault current and operating coil current
d. Fault current and restraining coil current
Q. Both voltage and current signals are required for
a. A plain over current relay
b. A differential relay
c. A directional relay
d. A biased directional relay
Q. When a transmission line is energized, the wave that propagates on it is
a. current wave only
b. voltage wave only
c. both (A) and (B)
d. power factor wave only
Q. Protective relays are devices that detect abnormal conditions in electrical circuits by measuring
a. current during abnormal condition
b. voltage during abnormal condition
c. constantly the electrical quantities which differ during normal and abnormal conditions
d. none of the above
Q. The voltage appearing across the contacts after opening of the circuit breaker iscalled______voltage.
a. recovery
b. surge
c. operating
d. arc
Q. Ionization in circuit breaker is facilitated by
a. high temperature
b. increase of mean free path
c. increasing field strength
d. all of the above
Q. In a circuit breaker the basic problem is to
a. maintain the arc
b. extinguish the arc
c. transmit large power
d. emit the ionizing electrons
Q. Overheating of relay contacts or contact born out is due to
a. slow making and breaking of load circuit contacts
b. foreign matter on the contact surface
c. too low contact pressure
d. all of the above