# Transformer MCQs

1. While conducting short-circuit test on a transformer the following side is short circuited

(a) High voltage side
(b) Low voltage side

(c) Primary side
(d) Secondary side

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

(a) Conservator
(b) Breather
(c) Buchholz relay
(d) Exciter

3. The purpose of providing an iron core in a transformer is to

(a) provide support to windings
(b) reduce hysteresis loss
(c) decrease the reluctance of the magnetic path
(d) reduce eddy current losses

4. No-load current in a transformer

(a) lags behind the voltage by about 75°
(b) leads the voltage by about 75°
(c) lags behind the voltage by about 15°
(d) leads the voltage by about 15°

5. The efficiency of a transformer will be maximum when

(a) copper losses = hysteresis losses
(b) hysteresis losses = eddy current losses
(c) eddy current losses = copper losses
(d) copper losses = iron losses

6. The permissible flux density in case of cold rolled grain oriented steel is around

(a) 1.7 Wb/m2
(b) 2.7 Wb/m2
(c) 3.7 Wb/m2
(d) 4.7 Wb/m2

7. Sumpner’s test is conducted on transformers to determine

(a) temperature
(b) stray losses
(c) all-day efficiency
(d) none of the above

8. The dielectric strength of transformer oil is expected to be

(a) 1 kV
(b) 33 kV
(c) 100 kV
(d) 330 kV

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

(a) copper loss
(b) magnetising current
(c) magnetising current and loss
(d) efficiency of the transformer

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

(a) high resistance
(b) high reluctance
(c) low resistance
(d) low reluctance

11. The no-load current drawn by the transformer is usually what per cent of the full-load current?

(a) 0.2 to 0.5 per cent
(b) 2 to 5 per cent
(c) 12 to 15 per cent
(d) 20 to 30 per cent

12. The degree of mechanical vibrations produced by the laminations of a transformer depends on

(a) tightness of clamping
(b) gauge of laminations
(c) size of laminations
(d) all of the above

13. A transformer core is laminated to

(a) reduce hysteresis loss
(b) reduce eddy current losses
(c) reduce copper losses
(d) reduce all above losses

14. 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

15. Which of the following does not change in a transformer?

(a) Current
(b) Voltage
(c) Frequency
(d) All of the above