# Switchgear and Protection MCQ Questions Part 2

Swithcgear and Protection MCQ Questions Part 2

## The fuse element is usually made of

The fuse element is usually made of:

1. Silver
2. Steel
3. Brass
4. Iron

## Most of relays in Electrical Power Systems are

Most of relays in Electrical Power Systems are:

1. Thermal relays
2. Electronic relays
3. Electromechanical relays
4. Microprocessor relays

## A circuit breaker on its own performs the function of

A circuit breaker on its own performs the function of:

1. Circuit interruption only
2. Detection only
3. Both detection and circuit interruption
4. None or above

Correct answer: 1. Circuit interruption only

## A circuit breaker is able to open under

A circuit breaker is able to open under:

3. Fault conditions
4. All of these

Correct answer: 4. All of these

## As compared to circuit breaker the fuse is

As compared to circuit breaker the fuse is

1. Is costlier
2. Of same cost
3. Is cheaper
4. None of these

## Current chopping mainly occurs in

Current chopping mainly occurs in:

1. Vacuum circuit breaker
2. Oil circuit breaker
3. Sf6 circuit breaker
4. Air-blast circuit breaker

Correct answer: 4. Air-blast circuit breaker

## Two fuse having wires of same material have fusing currents of 10 A and 15 A. The 10 A fuse has

Two fuse having wires of same material have fusing currents of 10 A and 15 A. The 10 A fuse has:

1. Smaller diameter
2. Larger diameter
3. Both will have same
4. None of these

Explanation: Fusing current is directly proportional to current by formula:

I ∝ d^3/2

## Which of following is an advantage of a low oil circuit breaker over the bulk oil circuit breaker

Which of following is an advantage of a low oil circuit breaker over the bulk oil circuit breaker:

1. It requires less space
2. It reduces risk of fire
3. It requires comparatively less oil
4. All of these

Correct answer: 4. All of these

## Rate of rise of restriking voltage depends on

Rate of rise of restriking voltage depends on:

1. Capacitance of system
2. Inductance of system
3. Type of circuit breaker
4. Inductance and Capacitance of system

Correct answer: 4. Inductance and Capacitance of system

## The making capacity of a circuit breaker is expressed mathematically as

The making capacity of a circuit breaker is expressed mathematically as:

1. 2.55 x Symmetrical breaking capacity
2. √2 x Symmetrical breaking capacity
3. √3 x Symmetrical breaking capacity
4. √4 x Symmetrical breaking capacity

Correct answer: 1. 2.55 x symmetrical breaking capacity