Top 250+ Solved Testing and Commissioning of Electrical Equipment’s MCQ Questions Answer
Q. When using air blast circuit breaker, current chopping is a phenomenon observedwhen
a. A long overhead line is switched off.
b. A bank of capacitors is switched off.
c. A transformer on no load is switched off.
d. A heavy load is switched off.
Q. Which type of air is used in air blast circuit breaker?
a. Ionised air
b. Air free from moisture
c. Air should have least CO2
d. Air must have oil mist.
Q. What is fusing factor?
a. The ratio of current rating of the fuse to the minimum fusing current
b. The ratio of minimum fusing current to the current rating of the fuse
c. The ratio of maximum fusing current to the current rating of the fuse
d. The ratio of minimum fusing current to the voltage rating of the fuse
Q. For a current upto 10A which material is used as the fusing element?
a. Copper
b. Silver
c. Alloy of lead and tin
d. Zinc
Q. Which among these is the least expensive protection for over current in lowvoltage system?
a. Rewirable fuse.
b. Isolator.
c. Circuit breaker.
d. Air breaker switch.
Q. Which among the following statement is true related to fuse?
a. Greater the current smaller is the time taken by the fuse to blow out.
b. Greater the current greater is the time taken by the fuse to blow out.
c. The current is directly proportion to the blow out time of fuse.
d. Is dependent on the temperature and atmospheric conditions.
Q. How is the restriking voltage measured?
a. RMS value
b. Peak value
c. Instantaneous value
d. Average value
Q. What is the interrupting medium in the contactor?
a. Air at atmospheric pressure.
b. SF6 gas
c. Oil
d. All of the above.
Q. Recovery voltage is the value of rms voltage that reappears across the poles of acircuit breaker before_______________
a. Restriking voltage
b. Final arc extinction
c. Rise of voltage
d. All of the above
Q. Why is it difficult to interrupt a capacitive circuit?
a. The current has a leading power factor.
b. The restriking voltage can be high.
c. Current magnitude is very small.
d. Stored energy in the capacitor is very high.
Q. Rate of rise of restriking voltage depend on_____________?
a. Type of circuit breaker.
b. Capacitance of the system.
c. Inductance of the system.
d. Both (b) and (c)
Q. On what factor does the rate of rise of restriking voltage (RRRV) depend?
a. System voltage.
b. Circuit power factor only
c. Switching conditions
d. Both (b) and (c).
Q. In a circuit breaker, the active recovery voltage depends upon which amongthese?
a. Circuit conditions.
b. Power factor.
c. Both (a) and (b)
d. None of the above
Q. What is restriking voltage?
a. The transient voltage that appears across the circuit breaker contacts at the instant of arc extinction.
b. The transient voltage that appears across the circuit breaker contacts at the end of arc extinction.
c. Both (a) and (b)
d. None of the above