TRANSFORMER part-1

1.The BDV of transformer oil should be

 (a) 20 kV (b) 30 kV

 (c) 40 kV (d) 50 kV 

b-Answer

2. The open circuit test of transformer determines

(a) Iron loss

(b) Copper loss at full load

(c) Copper loss at half load

(d) Total losses. 

a-Answer

3.Transformers placed in a room enclosed from all the four sides, the minimum spacing between the walls and the transformer should be

 (a) 0.5 m (b) 0.75 m

(c) 1 m (d) 1.25 m 

d-Answer

4.The path of a magnetic flux in a transformer should have

a. high resistance b. high reluctance

c. low resistance d. low reluctance

d-Answer 

5.At an atmospheric temperature of 45 deg C and keeping in view the working condition, the winding temperature of the transformer should not exceed

 (a) 80 deg C (b) 95 deg C

(c) 110 deg C (d) 130 deg C 

b-Answer

6.Primary winding of a transformer

a. is always a low voltage winding 

b. is always a high voltage winding

c. could either be a low or high voltage winding

d. none of the above 

c-Answer

7.Efficiency of a power transformer is of the order of

a. 100 percent b. 98 percent

c. 50 percent d. 25 percent

b-Answer

8.The maximum efficiency of a distribution transformer is

a. at no load b. at 50% full load

c. at 80% full load d. at full load 

b-Answer

9.A transformer transforms

a. voltage b. current

c. power d. frequency 

c-Answer

10.Transformer breaths in when

a. load on it increases b. load on it decreases

c. load remains constant d. none of the above 

b-Answer