Question 1

In a biased differential relay the bias is defined as a ratio of

Accepted Answer

A) Number of turns of restraining and operating coil 
B) Operating coil current and restraining coil current 
C) Fault current and operating coil current 
D) Fault current and restraining coil current 
A) Number of turns of restraining and operating coil 
B) Operating coil current and restraining coil current 
C) Fault current and operating coil current 
D) Fault current and restraining coil current B

Question 2

A reactance relay is

Accepted Answer

A) Voltage restrained overcurrent relay 
B) Voltage restrained directional relay 
C) Directional restrained overcurrent relay 
D) Directional restrained over voltage relay 
A) Voltage restrained overcurrent relay 
B) Voltage restrained directional relay 
C) Directional restrained overcurrent relay 
D) Directional restrained over voltage relay C

Question 3

Reactance relays are used for phase fault in.......line

Accepted Answer

A) Short 
B) Medium 
C) Long 
D) All of the above 
A) Short 
B) Medium 
C) Long 
D) All of the above A

Question 4

Impedance relay may use

Accepted Answer

A) Balance beam structure 
B) Induction cup structure 
C) Shaded pole structure 
D) Either A or B 
A) Balance beam structure 
B) Induction cup structure 
C) Shaded pole structure 
D) Either A or B

Question 5

A differential relay response to

Accepted Answer

A) Algebraic difference of two or more similar electrical quantities 
B) Phasor difference of two or more similar electrical quantities 
C) Algebraic difference between two currents 
D) Algebraic difference between two voltages 
A) Algebraic difference of two or more similar electrical quantities 
B) Phasor difference of two or more similar electrical quantities 
C) Algebraic difference between two currents 
D) Algebraic difference between two voltages

Question 6

In an inverse definite minimum time, electromagnetic type over current relay, the minimum time feature is achieved because of

Accepted Answer

A) Saturation of the magnetic circuit 
B) Proper mechanical design 
C) Appropriate time delay element 
D) Electromagnetic damping 
A) Saturation of the magnetic circuit 
B) Proper mechanical design 
C) Appropriate time delay element 
D) Electromagnetic damping

Question 7

Both voltage and current signals are required for

Accepted Answer

A) A plain over current relay 
B) A differential relay 
C) A directional relay 
D) A biased directional relay 
A) A plain over current relay 
B) A differential relay 
C) A directional relay 
D) A biased directional relay

Question 8

The domains of power system where directional over current relay is indispensable are

Accepted Answer

A) In case of parallel feeder protection 
B) In case of ring main feeder protection 
C) Both A and B 
D) None of the above 
A) In case of parallel feeder protection 
B) In case of ring main feeder protection 
C) Both A and B 
D) None of the above

Question 9

Reactance relay is normally used for protection against

Accepted Answer

A) Earth fault only 
B) Phase fault only 
C) Both earth and phase faults 
D) None of the above 
A) Earth fault only 
B) Phase fault only 
C) Both earth and phase faults 
D) None of the above

Question 10

The structure used in reactance relay is

Accepted Answer

A) Induction cup 
B) Double induction loop 
C) Single induction loop 
D) Either A or B 
A) Induction cup 
B) Double induction loop 
C) Single induction loop 
D) Either A or B

Question 11

Threshold characteristics of a plain impedance relay in a complex Z plane is a

Accepted Answer

A) Circle passing through origin 
B) Circle with the centre at the origin 
C) Straight line passing through origin 
D) Straight line offset from the origin 
A) Circle passing through origin 
B) Circle with the centre at the origin 
C) Straight line passing through origin 
D) Straight line offset from the origin

Question 12

Impedance relay can be used for

Accepted Answer

A) Phase faults only 
B) Earth faults only 
C) Both earth and phase faults 
D) None of the above 
A) Phase faults only 
B) Earth faults only 
C) Both earth and phase faults 
D) None of the above

Question 13

On transient fault OC and impedance relay

Accepted Answer

A) Under reaches 
B) Over reaches 
C) Reach unaffected 
D) None of the above 
A) Under reaches 
B) Over reaches 
C) Reach unaffected 
D) None of the above

Question 14

Differential relays are used for protection of equipments against

Accepted Answer

A) Internal faults 
B) Over current 
C) Reverse current 
D) Reverse power 
A) Internal faults 
B) Over current 
C) Reverse current 
D) Reverse power

Question 15

The operating characteristics of the reactance relay in the complex impedance plane is a

Accepted Answer

A) Circle with its origin at the centre of the R-X plane 
B) Circle passing through the origin 
C) Straight line passing through the origin 
D) Straight line parallel to the X axis 
A) Circle with its origin at the centre of the R-X plane 
B) Circle passing through the origin 
C) Straight line passing through the origin 
D) Straight line parallel to the X axis

Question 16

Differential relays are used for protection of

Accepted Answer

A) Feeders 
B) Alternators 
C) Transformers 
D) All of the above 
A) Feeders 
B) Alternators 
C) Transformers 
D) All of the above

Question 17

An impedance is relay is a

Accepted Answer

A) Voltage restrained over current relay 
B) Voltage restrained directional relay 
C) Directional restrained over current relay 
D) Directional restrained over voltage relay 
A) Voltage restrained over current relay 
B) Voltage restrained directional relay 
C) Directional restrained over current relay 
D) Directional restrained over voltage relay

In a biased differential relay the bias is defined as a ratio of

A reactance relay is

Reactance relays are used for phase fault in.......line

Impedance relay may use

A differential relay response to

In an inverse definite minimum time, electromagnetic type over current relay, the minimum time feature is achieved because of

Both voltage and current signals are required for

The domains of power system where directional over current relay is indispensable are

Reactance relay is normally used for protection against

The structure used in reactance relay is

Threshold characteristics of a plain impedance relay in a complex Z plane is a

Impedance relay can be used for

On transient fault OC and impedance relay

Differential relays are used for protection of equipments against

The operating characteristics of the reactance relay in the complex impedance plane is a

Differential relays are used for protection of

An impedance is relay is a

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Power System Protection and Equipment

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Electrical Protection and Safety: Part B

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Exam 12: Understanding Relays for Power System Protection

In a biased differential relay the bias is defined as a ratio of

A reactance relay is

Reactance relays are used for phase fault in.......line

Impedance relay may use

A differential relay response to

In an inverse definite minimum time, electromagnetic type over current relay, the minimum time feature is achieved because of

Both voltage and current signals are required for

The domains of power system where directional over current relay is indispensable are

Reactance relay is normally used for protection against

The structure used in reactance relay is

Threshold characteristics of a plain impedance relay in a complex Z plane is a

Impedance relay can be used for

On transient fault OC and impedance relay

Differential relays are used for protection of equipments against

The operating characteristics of the reactance relay in the complex impedance plane is a

Differential relays are used for protection of

An impedance is relay is a

Electrical Protection and Circuit Breakers

Electrical Protection and Transmission Line Characteristics

Power System Protection and Equipment

Electrical Protection and Safety: Part A

Electrical Protection and Safety: Part B

Protective Relays and Circuit Breakers for Electrical Systems

Circuit Breakers and Fuses

Electric Arc and Circuit Breaker Protection

Electrical Components and Circuit Breakers

Electrical Protection and Switchgear

Relaying Schemes and Techniques for Electrical Equipment Protection

Filters