Protective Relays MCQ Questions with Answers

The relay is an electrical protection device that detects fault and supplies information to a circuit breaker which in turn performs circuit interruption. Given below are protection relays MCQ questions with answers.

The function of a relay is to

The function of a relay is to:

1. Detect fault
2. Interrupt circuit
3. Detect and interrupt
4. Both of these

Correct answer: 1. Detect fault

Relays can be actuated by

Relays can be actuated by:

1. Frequency of waveform
2. Current level
3. Phase angle
4. All of these

Correct answer: 4. All of these

In IDMTL the time multiplier setting can be varied by

In IDMTL the time multiplier setting can be varied by:

1. Varying turns on upper electromagnet
2. Altering by torsion head
3. Using CCVT
4. None of these

Correct answer: 2. Altering by torsion head

Plug setting of an electromagnetic relay can be altered by

Plug setting of an electromagnetic relay can be altered by:

1. Using a CCVT
2. Varying number of ampere turns
3. Changing width of magnetic path air gap
4. None of these

Correct answer: 2. Varying number of ampere turns

Backup protection is provided so as to

Backup protection is provided so as to:

1. Increase sensitivity
2. Increase speed of protection system
3. To act in case of failure of primary protection
4. None of these

Correct answer: 3. To act in case of failure of primary protection

Induction relays are used with

Induction relays are used with:

1. AC
2. DC
3. Both of these
4. None of these

Correct answer: 1. AC

The pick-up current of a 100/5 transformer having a current setting of 300% will be

The pick-up current of a 100/5 transformer having a current setting of 300% will be:

1. 2.5 Amps
2. 5 Amps
3. 10 Amps
4. 15 Amps

Correct answer: 4. 15 Amps

Explanation: Pick-up current = Rated secondary current * Current setting

Pick up current = 5 * 3 = 15 A

Here is a Similar Example

Microprocessor relay is a type of

Microprocessor relay is a type of:

1. Electromechanical relay
2. Static analog relay
3. Static digital relay
4. All of these

Correct answer: 3. Static digital relay

A relay has pick-up value of 10 A and the fault current in the relay coil is 25 A. Its plug-setting multiplier

A relay has pick-up value of 10 A and the fault current in the relay coil is 25 A. Its plug-setting multiplier:

1. 2.5 A
2. 25 A
3. 35 A
4. 250 A

Correct answer: 2.5 A

P.S.M. = Fault current in relay coil/Pick-up current = 25 A/10 A = 2.5 A

Modern Microprocessor relays are loaded with the function of

Modern Microprocessor relays are loaded with the function of:

1. Memorized fault information
2. Status information
3. Accurate relay settings
4. All of these

Correct answer: 4. All of these

So that was all about Protective Relays MCQ Questions.

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