Power System Protection MCQs Part 21

Contents

- 1 The normal current in power line is 120 A. If short circuit fault occurs on the line, the one can expect the short-circuit current to be
- 2 The fusing current I for a round wire having diameter d is given mathematically by
- 3 Which of the following CB is generally used in railway applications
- 4 A fuse is always connected in
- 5 Arc interruption takes place in oil circuit breaker when

## The normal current in power line is 120 A. If short circuit fault occurs on the line, the one can expect the short-circuit current to be

The normal current in power line is 120 A. If short circuit fault occurs on the line, the one can expect the short-circuit current to be:

- 120 A
- 200 A
- 500 A
- More than 1000 A

Correct answer: 4. More than 1000 A

Explanation: The short circuit current is generally more than 10 times of the normal current. Therefore, one can expect the short-circuit current to be more than 1000 A.

## The fusing current I for a round wire having diameter d is given mathematically by

The fusing current I for a round wire having diameter d is given mathematically by:

- I ∝ d
- I ∝ d^2
- I ∝ d^3/2
- None of these

Correct answer: 3. I ∝ d^3/2

## Which of the following CB is generally used in railway applications

Which of the following CB is generally used in railway applications:

- Air break CB
- Bulk oil CB
- Low oil CB
- SF6 CB

Correct answer: 1. Air break CB

## A fuse is always connected in

A fuse is always connected in:

- Series with circuit
- Parallel with circuit
- Series-parallel configuration with circuit
- None of these

Correct answer: 1. Series with circuit

## Arc interruption takes place in oil circuit breaker when

Arc interruption takes place in oil circuit breaker when:

- Voltage goes through zero
- Current goes through zero
- Contacts move apparat
- None of these

Correct answer: 2. Current goes through zero

See complete list of Power System Protection MCQs here