# Transformer MCQs Part 13

## The efficiency of a transformer will be maximum if

The efficiency of a transformer will be maximum if

1. Copper losses = hysteresis losses
2. Copper losses = iron losses
3. Eddy current losses = copper losses
4. Hysteresis losses = eddy current losses

Correct answer: 2. Copper losses = iron losses

## The efficiency of two identical transformers under load conditions can be determined using which test

The efficiency of two identical transformers under load conditions can be determined using which test

1. Back-to-back test
2. Open circuit test
3. Short-circuit test
4. Any of above

Correct answer: 1. Back-to-back test

## The primary coil of a transformer is connected to an ac source of 60 V. The secondary coil is connected to a 330 Ω load. The turns ratio of transformer are 3:1. The secondary voltage is

The primary coil of a transformer is connected to an ac source of 60 V. The secondary coil is connected to a 330 Ω load. The turns ratio of transformer are 3:1. The secondary voltage is

1. 18 V
2. 180 V
3. 2 V
4. 20 V

Correct answer: 4. 20 V

## Efficiency of a transformer, under heavy loads, is somewhat low since

Efficiency of a transformer, under heavy loads, is somewhat low since

1. Copper loss becomes high in proportion to the output
2. Iron loss is increased considerably
3. Secondary output is much less as compared to primary input
4. Voltage drop both in primary and secondary becomes large

Correct answer: 1. Copper loss becomes high in proportion to the output

## The dielectric strength of transformer oil is expected to be

The dielectric strength of transformer oil is expected to be

1. 10 kV
2. 100 kV
3. 33 kV
4. 330 kV

Correct answer: 3. 33 kV