Electrical Engineering MCQs on Transformer

## The efficiency of a transformer will be maximum if

The efficiency of a transformer will be maximum if

- Copper losses = hysteresis losses
- Copper losses = iron losses
- Eddy current losses = copper losses
- 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

- Back-to-back test
- Open circuit test
- Short-circuit test
- 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

- 18 V
- 180 V
- 2 V
- 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

- Copper loss becomes high in proportion to the output
- Iron loss is increased considerably
- Secondary output is much less as compared to primary input
- 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

- 10 kV
- 100 kV
- 33 kV
- 330 kV

Correct answer: 3. 33 kV