# Transformer MCQs Part 10

Transformer MCQs Part 10

## The temperature rise of transformer is directly proportional to

The temperature rise of transformer is directly proportional to:

1. Apparent power
2. Leakage reactance
3. Reactive power
4. All of these
5. None of these

Correct answer: 1. Apparent power

Explanation: Two types of losses occurring in a transformer are:

1. Iron losses: Depend upon voltage
2. Copper losses: Depend upon current

The losses create heat thus resulting in rise of temperature. Since iron losses depend upon voltage and copper losses depend upon current, the total temperature rise depends upon volt-ampere product only.

## When secondary of transformer is short-circuited, the primary inductance

When secondary of transformer is short-circuited, the primary inductance:

1. Is increased
2. Is decreased
3. Remains the same
4. None of these

Correct answer: 2. Is decreased

## The no load input of power transformer practically equals which of the following loss of transformer

The no load input of power transformer practically equals which of the following loss of transformer:

1. Copper
2. Iron
3. Eddy current
4. Sum of all of above

Correct answer: 2. Iron

## The transformer works on

The transformer works on:

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

Correct answer: 1. AC only

## A 3300/330, 50 kVA ideal transformer has 50 turns in secondary. The number of turns in primary side will be

A 3300/330, 50 kVA ideal transformer has 50 turns in secondary. The number of turns in primary side will be:

1. 200
2. 500
3. 750
4. 1050

Correct answer: 2. 500

Explanation

K = E2/E1 = 330/3300 = 0.1

N2/N1 = K

50/N1 = 0.1

N1 = 500