Electrical Engineering MCQs on Transformer
When a given transformer runs at its rated voltage but reduced frequency, its
When a given transformer runs at its rated voltage but reduced frequency, its
- Core flux density is increased
- Core flux density is reduced
- Flux density remains unaffected
- Iron losses are reduced
Correct answer: 1. Core flux density is increased
The efficiencies of transformers compared with that of electric motors having same power are
The efficiencies of transformers compared with that of electric motors having same power are
- About the same
- Much higher
- Much smaller
- Somewhat smaller
Correct answer: 2. Much higher
The starting torque of a squirrel-cage induction motor is
The starting torque of a squirrel-cage induction motor is
- Low
- Negligible
- Same as full-load torque
- Slightly more than full-load torque
Correct answer: 1. Low
The power factor of an induction motor under no-load conditions will be around
The power factor of an induction motor under no-load conditions will be around
- 0.2 lagging
- 0.2 leading
- 0.5 leading
- Unity
Correct answer: 1. 0.2 lagging
If percentage impedances of the two transformers that are working in parallel are different, then
If percentage impedances of the two transformers that are working in parallel are different, then
- Parallel operation will be not possible
- Parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the common load
- Power factors of both the transformers will be same
- Transformers will be overheated
Correct answer: 2. Parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the common load