Multiple Choice Question (MCQ) of Protective Relays
Multiple Choice Question (MCQ) of Protective Relays
Manisha tyagi
1
3915
1. A single phasing relay can be used with
1ɸ motor
2 ɸ motor
3 ɸ motor
All of these
Correct Answer
Wrong Answer
2. A relay is used to
Break the fault current
Sense the fault
Sense the fault and direct to trip the circuit breaker
All of these
Correct Answer
Wrong Answer
3. In impedance relay, current element torque should be
Equal to voltage element torque
Greater than voltage element torque
Less than voltage element torque
None of these
Correct Answer
Wrong Answer
4. Over current fault is most likely in
Transformer
Overhead line equipment
Alternator
Motors
Correct Answer
Wrong Answer
5. Distance relays are generally
Impedance type
MHO type
Reactance type
All of these
Correct Answer
Wrong Answer
6. Instantaneous relay should operate within
0.0001 sec
0.001 sec
0.01 sec
0.1 sec
Correct Answer
Wrong Answer
7. In an impedance relay, fault current is maximum if fault occurs near the
Relay
Center of the line
Transformer
None of these
Correct Answer
Wrong Answer
8. Relays for transmission line protection are
In three zones
In two zones
Independent of zone
None of these
Correct Answer
Wrong Answer
9. Time classification of relays includes
Instantaneous relays
Definite time lag
Inverse time lag
All of these
Correct Answer
Wrong Answer
10. Directional relays responds to
Power
Voltage
Current
Reactance
Correct Answer
Wrong Answer
11. For phase fault on long line, which relay is used?
MHO relays
Reactance relays
Impedance relays
All of these
Correct Answer
Wrong Answer
12. Under voltage relays are used for
Motors
Alternators
Bus bars
All of these
Correct Answer
Wrong Answer
13. An impedance relay is used for
Earth faults
Interphase faults
Both (a) and (b)
None of these
Correct Answer
Wrong Answer
14. Over voltage may be due to
Lightning impulse waveform
50 Hz a.c.
Peak value of 50 Hz a.c.
All of these
Correct Answer
Wrong Answer
15. In oil circuit breakers, dielectric strength of oil should be
High
Low
Medium
None of these
Correct Answer
Wrong Answer
16. Negative Phase sequence relay is used to protect ……. from phase to phase faults
Bus bar
Transformer
Generator
Electric Heater
Correct Answer
Wrong Answer
17. Distance relay operates on ………………….
Magnitude of voltage
Magnitude of current
Ratio of voltage and current
Magnitude of reactive power
Correct Answer
Wrong Answer
18. A protective relay …………..
detects the fault location
interrupts the fault current
eparates the electrical circuit in case of faul
operates same as electrical fuse
Correct Answer
Wrong Answer
19. Buchholz relays are used to protect ………………
Electrical Transformer
Electrical Generator
Electrical Bus Bar
Electrical Motor
Correct Answer
Wrong Answer
20. Earth fault protection is provided by employing an Over current relay between phase and earth:
True
False
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