Transformers

1. If a transformer is switched on to a voltage more than the rated voltage

its power factor will deteriorate
its power factor will increase
its power factor will remain unaffected
its power factor will be zero

Detailed SolutionIf a transformer is switched on to a voltage more than the rated voltage

2. A transformer can have regulation closer to zero

on full-load
on overload
on leading power factor
on zero power factor

Detailed SolutionA transformer can have regulation closer to zero

3. No-load on a transformer is carried out to determine

copper loss
magnetising current
magnetising current and loss
efficiency of the transformer

Detailed SolutionNo-load on a transformer is carried out to determine

4. The maximum load that a power transformer can carry is limited by its

temperature rise
dielectric strength of oil
voltage ratio
copper loss

Detailed SolutionThe maximum load that a power transformer can carry is limited by its

5. Hysteresis loss in a transformer varies as (Bmax = maximum flux density)

$${{ ext{B}}_{max }}$$
$${{ ext{B}}_{max }}^{1.6}$$
$${{ ext{B}}_{max }}^{1.85}$$
$${{ ext{B}}_{max }}^{2.4}$$

Detailed SolutionHysteresis loss in a transformer varies as (Bmax = maximum flux density)

6. Which type of winding is used in 3phase shell-type transformer?

Circular type
Sandwich type
Cylindrical type
Rectangular type

Detailed SolutionWhich type of winding is used in 3phase shell-type transformer?

7. Insertion of resistance in the rotcir of an induction motor to develop a given torque

decreases the rotor current
increases the rotor current
rotor current becomes zero
rotor current rernains same

Detailed SolutionInsertion of resistance in the rotcir of an induction motor to develop a given torque

8. For given applied voltage, with the increase in frequency of the applied voltage

eddy current loss will decrease
eddy current loss will increase
eddy current loss will remain unchanged
none of the above

Detailed SolutionFor given applied voltage, with the increase in frequency of the applied voltage

9. Which of the following protection is normally not provided on small distribution transformers?

Overfluxing protection
Buchholz relay
Overcurrent protection
All of the above

Detailed SolutionWhich of the following protection is normally not provided on small distribution transformers?

10. A transformer core is laminated to

reduce hysteresis loss
reduce eddy current losses
reduce copper losses
reduce all above losses

Detailed SolutionA transformer core is laminated to

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