Electrical Engineering Mcqs Practice Test

Question 1

For a transformer, operating at constant load current, maximum efficiency will occur at______________?

Accepted Answer

D. unity power factor

Question 2

A Transformer transforms____________?

Accepted Answer

D. power

Question 3

A transformer can have regulation closer to zero___________?

Accepted Answer

C. on leading power factor

Question 4

In a transformer the resistance between its primary and secondary should be_____________?

Accepted Answer

D. infinity

Question 5

The secondary of a current transformer is always short-circuited under operating conditions because it____________________?

Accepted Answer

A. avoids core saturation and high voltage induction

Question 6

A shell-type transformer has_________?

Accepted Answer

B. reduced magnetic leakage

Question 7

N atural air coo ling is generally restricted for transformers up to__________?

Accepted Answer

A. 1.5 MVA

Question 8

The size of a transformer core will depend on__________?

Accepted Answer

D. A. and B. both

Question 9

The secondary winding of which of the following transformers is always kept closed?

Accepted Answer

D. Current transformer

Question 10

The function of breather in a transformer is___________?

Accepted Answer

D. to arrest flow of moisture when outside air enters the transformer

Question 11

The efficiencies of transformers compared with that of electric motors of the same power are____________?

Accepted Answer

C. much higher

Question 12

The transformer oil should have _______ volatility and _______ viscosity?

Accepted Answer

A. low,low

Question 13

In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of_________________?

Accepted Answer

A. less than 15 A

Question 14

For the parallel operation of single phase transformers it is necessary that they should have___________?

Accepted Answer

B. same polarity

Question 15

Minimum voltage regulation occurs when the power factor of the load is_____________?

Accepted Answer

C. leading

Question 16

Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is_________________?

Accepted Answer

A. approximately equal to one

Question 17

Short circuit test on transformers is conducted to determine____________?

Accepted Answer

B. copper losses

Question 18

If a transformer is switched on to a voltage more than the rated voltage______________?

Accepted Answer

A. its power factor will deteriorate

Question 19

Open circuit test on transformers is conducted to determine____________?

Accepted Answer

C. core losses

Question 20

Part of the transformer which is most subject to damage from overheating is_____________?

Accepted Answer

C. winding insulation