Which of the following parts of a transformer is from outside ?

A. Bushings
B. Core
C. Primary winding
D. Secondary winding

Which of the following insulating materials can withstand the highest temperature safely ?

A. Cellulose
B. Asbestos
C. Mica
D. Glass fibre

The efficiency of two identical transformers under load conditions can be determined by_______________?

A. Short-circuit test
B. Back-to-back test
C. Open circuit test
D. Any of the above

Which of the following acts as a protection against high voltage surges due to lightning and switching ?

A. Horn gaps
B. Thermal overload relays
C. Breather
D. Conservator

A good voltage regulation of a transformer means________________?

A. Output voltage fluctuation from no load to full load is least
B. Output voltage fluctuation with power factor is least
C. Difference between primary and secondary voltage is least
D. Difference between primary and secondary voltage is maximum

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

A. Overfluxing protection
B. Buchholz relay
C. Overcurrent protection
D. All of the above

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

A. 0.8 leading power factor
B. 0.8 lagging power factor
C. Zero power factor
D. Unity power factor

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

A. Zero
B. 10 q
C. 1000 q
D. Infinity

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

A. Avoids core saturation and high voltage induction
B. Is safe to human beings
C. Protects the primary circuit
D. None of the above

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

A. Less than 15 a
B. More than 15 a
C. 15 a
D. None of the above