Arc Phenomenon in Circuit Breakers - MCQs with answersQ1. When a fault occurs in a high voltage transmission line, what happens first?
a. Circuit breaker operates then the relay.
b. Relay operates and then the circuit breaker.
c. Relay operates, then successively the isolator and the circuit breaker.
d. Isolator operates, then successively the relay and the circuit breaker.View Answer / Hide Answer
Q2. Which part of the circuit breaker is helpful in breaking the current?
ANSWER: b. Relay operates and then the circuit breaker.
a. Trip coil.
d. Handle.View Answer / Hide AnswerQ3. Which type of tripping is generally preferred for the circuit breaker?
c. Depending on the voltage level
d. None of the aboveView Answer / Hide AnswerQ4. The arc resistance depends on which among the following factors?
a. Cross section of the arc.
b. Length of the arc.
c. Degree of ionisation
d. All of the above.View Answer / Hide Answer
Q5. How is the initiation of electric arc at the instant of contact separation caused?
ANSWER: d. All of the above.
a. Thermionic emission of electrons.
b. Field emission of electrons.
c. Both (a) and (b)
d. None of these.View Answer / Hide Answer
Q6. Arcing voltage will be the least in case of
ANSWER: c. Both (a) and (b)
d. TungstenView Answer / Hide AnswerQ7. What is the arc voltage in a circuit breaker?
a. In phase with the arc current.
b. Lagging the arc current by 90°
c. Leading the arc current by 90°
d. Lagging the arcing current by 180°View Answer / Hide Answer
Q8. What happens in the arc extinction using high resistance method?
ANSWER: a. In phase with the arc current.
a. Arc resistance is decreased with time.
b. Arc resistance is increased with time.
c. No change it remains same.
d. Arc resistance is kept zero.View Answer / Hide Answer
Q9. When using low resistance method for arc extension what is the value of arc resistance?
ANSWER: b. Arc resistance is increased with time.
a. Arc resistance is zero.
b. Arc resistance is high
c. Arc resistance is low
d. Arc resistance is very highView Answer / Hide Answer
Q10. The resistance of an electric arc can be increased by
ANSWER: c. Arc resistance is low
a. Increasing the concentration of ionised particles.
b. Reducing the arc length.
c. Splitting the arc.
d. Increasing the arc cross section.View Answer / Hide Answer
ANSWER: c. Splitting the arc.