Switchgear Protections MCQ Questions & Answers

31

The torque produced in induction type relay (shaded pole structure) is

A) inversely proportional to the current B) inversely proportional to the square of the current C) proportional to the current D) proportional to square of the current

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Answer & Solution

Answer: Option B

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32

What will be the reflection co-efficient of the wave of load connected to transmission line if surge impedance of the line is equal to load ?

A) Zero B) Unity C) Infinity D) None of the above

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Answer & Solution

Answer: Option A

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33

Burden of a protective relay is the power

A) required to operate the circuit breaker B) absorbed by the circuit of relay C) developed by the relay circuit D) none of the above

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Answer & Solution

Answer: Option B

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34

The line insulation is the insulation level of the station equipment.

A) less than B) same as C) more than D) proportional to E) not directly related with

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Answer & Solution

Answer: Option E

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35

A balanced 3-phase system consists of

A) zero sequence currents only B) positive sequence currents only C) negative and zero sequence currents D) zero, negative and positive sequence currents

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Answer & Solution

Answer: Option B

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36

The delay fuses are used for the protection of ________ .

A) motors B) power outlet circuits C) fluorescent lamps D) light circuits

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Answer & Solution

Answer: Option A

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37

Ungrounded neutral transmission system is not recommended because of system

A) insulation being overstressed due to over voltages B) insulation overstress may lead to failure and subsequent phase to phase faults C) being inadequately protected against ground fault D) all of the above

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Answer & Solution

Answer: Option D

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38

Induction cup relay is operated due to changes in

A) current B) voltage C) impedance D) all of the above

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Answer & Solution

Answer: Option D

Solution:

The induction cup relay operates based on the principle of electromagnetic induction, which produces torque in the relay mechanism.

Current: Changes in current generate a magnetic field, influencing the operation of the relay.

Voltage: Variations in voltage also affect the electromagnetic field and contribute to the relay's operation.

Impedance: As impedance changes, it alters the relationship between current and voltage, impacting the electromagnetic torque and thus the relay's activation.

Since the relay responds to changes in current, voltage, and impedance, all of the above factors contribute to its operation.

Therefore, Option D is the correct answer.

39

Which of the following parameter can be neglected for a short line?

A) Inductance B) Capacitance C) Resistance D) Reactance

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Answer & Solution

Answer: Option B

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40

Shunt capacitance is neglected while considering

A) short transmission line B) medium transmission line C) long transmission line D) medium and long transmission lines

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Answer & Solution

Answer: Option A

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Switchgear Protections MCQ Questions & Answers | Electrical Engineering