Transformer. Part – 3

21. In a transformer the energy is conveyed from primary to secondary

A. Through cooling coil

B. Through air

C. By the flux

D. None of the above

22. Which of the following is not a part of transformer installation?

A. Conservator

B. Breather

C. Buchholz relay

D. Exciter           

23. Harmonics in transformer result in

A. Increased core losses

B. Increased I²R losses

C. Magnetic interference with communication circuits

D. All of the above

24. The no-load current drawn by transformer is usually what percent of the full-load current?

A. 0.2 to 0.5 percent

B. 2 to 5 percent

C. 12 to 15 percent

D. 20 to 30 percent

25. Which of the following parts of a transformer is visible from outside?

A. Bushings

B. Core

C. Primary winding

D. Secondary winding

26. The magnetizing current of a transformer is usually small because it has

A. Small air gap

B. Large leakage flux

C. Laminated silicon steel core

D. Fewer rotating parts 

27. The core flux in transformer depends on

A. Supply voltage

B. Supply voltage and frequency

C. Supply voltage frequency and load

D. Supply voltage and load

28.  In a transformer

A. both OC and SC tests are conducted on LV side

B. OC test is conducted on LV side and SC test is conducted on HV side

C. OC test is conducted on HV side and SC test is conducted on LV side

D. both OC and SC tests are conducted on HV side

29. The use of higher flux density in the transformer design

A. Reduces the weigh per KVA

B. Increases the weigh per KVA

C. Has no relation with the weight of transformer

D. None of the above

30. Conservator tank is used in transformer due to

A. To act as an oil storage

B. For better cooling of transformer

C. None of the above

D. To take up the expansion of oil due to temperature rise