Multiple Choice Question (MCQ) of Protective Relays page-1

1.A single phasing relay can be used with

a) 1ɸ motor
b) 2^r ɸ motor
c) 3 ɸ motor
d) All of these

Ans: (c)

2. A relay is used to

a) Break the fault current
b) Sense the fault
c) Sense the fault and direct to trip the circuit breaker
d) All of these

Ans: (c)

3. In impedance relay, current element torque should be

a) Equal to voltage element torque
b) Greater than voltage element torque
c) Less than voltage element torque
d) None of these

Ans: (a)

4. Over current fault is most likely in

a) Transformer
b) Overhead line equipment
c) Alternator
d) Motors

Ans: (b)

5. Plug setting of a relay can be changed by changing

a) Air gap
b) Back up stop
c) Number of ampere turns
d) All of these

Ans: (c)

6. Distance relays are generally

a) Impedance type
b) MHO type
c) Reactance type
d) All of these

Ans: (b)

7. Buchholz relay is used to protect against

a) Inter-turn fault
b) External faults
c) Rotor faults
d) Every internal faults

Ans: (d)

8. Instantaneous relay should operate within

a) 0.0001 sec
b) 0.001 sec
c) 0.01 sec
d) 0.1 sec

Ans: (c)

9. MHO relay is inherently a

a) Directional type
b) Non-directional type
c) Unidirectional type
d) None of these

Ans: (a)

10. Basic relay connection requirement is that the relay must operate for

a) Load
b) Internal faults
c) Both (a) and (b)
d) None of these

Ans: (b)

Index