Switchgear Protection Objective Questions and Answers - ObjectiveBooks

Switchgear Protection Objective Questions and Answers

Practice Test: Question Set - 15


1. Thermal circuit breaker has
    (A) Delayed trip action
    (B) Instantaneous trip action
    (C) Both of the above
    (D) None of the above

2. Magnetic circuit breaker has _________ trip action.
    (A) Delayed
    (B) Instantaneous
    (C) Both of the above
    (D) None of the above

3. The relay operating speed depends upon
    (A) The spring tension
    (B) The rate of flux built up
    (C) Armature core air gap
    (D) All of the above

4. Air blast circuit breaker is used for
    (A) Over currents
    (B) Short duty
    (C) Intermittent duty
    (D) Repeated duty

5. Directional relays are based on flow of
    (A) Power
    (B) Current
    (C) Voltage wave
    (D) All of the above

6. The voltage appearing across the contacts after opening of the circuit breaker is called _________voltage.
    (A) Recovery
    (B) Surge
    (C) Operating
    (D) Arc

7. The ground wire should not be smaller than No ________ copper.
    (A) 2
    (B) 4
    (C) 6
    (D) 10

8. The reflection coefficient at the open circuited end of a transmission line.
    (A) Zero
    (B) Infinity
    (C) Unity
    (D) None of the above

9. Discrimination between main and back up protection is provided by the use of relays which are
    (A) Fact
    (B) Sensitive
    (C) Slow
    (D) None of the above

10. Short-circuit currents are due to
    (A) Single phase to ground faults
    (B) Phase to phase faults
    (C) Two phase to ground faults
    (D) Any of these

11. Distance relays are generally
    (A) Split-phase relays
    (B) Reactance relays
    (C) Impedance relays
    (D) None of the above

12. Which of the following devices will receive voltage surge first travelling on the transmission line?
    (A) Lightning arresters
    (B) Relays
    (C) Step-down transformer
    (D) Switchgear

13. Arc in a circuit breaker is interrupted at
    (A) Zero current
    (B) Maximum current
    (C) Minimum voltage
    (D) Maximum voltage

14. If the fault occurs near the impedance relay, the VII ratio will be
    (A) Constant for all distances
    (B) Lower than that of if fault occurs away from the relay
    (C) Higher than that of if fault occurs away from the relay
    (D) None of the above

15. The power loss is an important factor for the design of
    (A) Transmission line
    (B) Motor
    (C) Generator
    (D) Feeder

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