Electric transformer - multi choice questions (mcq) - Electrical input

## Sunday, August 12, 2018

Electric Transformer mcq

1. A transformer core is laminated to following which :----
(a) reduce copper losses
(b) reduce hysteresis loss
(c) reduce eddy current losses
(d) none of above
Ans: c

2. Which of the following does not change in a transformer----
(a) Voltage
(b) Frequency
(c) Current
(d) All of the above
Ans:- b

3. The path of a magnetic flux in a transformer  -------
(a)  low reluctance
(b)  high resistance
(c)   low reluctance
(d)    low reactance
Ans:- c

4. Sumpner’s test is conducted on trans-formers determine which of following---
(a) all-day efficiency
(b) stray losses
(c) temperature
(d) none of the above
Ans:- c

5. No-load current in a transformer
(a) leads the voltage by about 15°
(b) lags behind the voltage by about 75°
(c) leads the voltage by about 75°
(d) lags behind the voltage by about 75°
Ans:- d

6. A transformer transforms
(a) current
(b) voltage
(c) frequency
(d) power
Ans:- d

7. Efficiency of a power transformer --------
(a) 50 %
(b) 80 %
(c) 98 %
(d) 100 %
Ans:- c

8. A common method of cooling a power transformer is
(a) oil cooling
(b) air blast cooling
(c) natural air cooling
(d) None of the above
Ans:- a

9. In a transformer routine efficiency depends upon
(a) frequency
(c) power factor of load
(d) both (b) and (c)
Ans:- write answer in comment box

10.  Natural oil cooling is used for transformers up to a rating of
(a)250 kVA
(b) 500 kVA
(c) 1500 kVA
(d) 3000 kVA
Ans:- d

11. The maximum etticiency ot a distnbution transtormer is
(a) at 50% full load
(b) at 80% full load
(c) at full load
(d) at no load
Ans:- a

12.  The power transformer is a constant
(a) main flux device
(b) power device
(c) voltage device
(d)current device
Ans:- a

13. The chemical used in breather-------
(a) silica gel
(b) sodium chloride
(c)  fiber
(d) silica sand
Ans:- a

14. The kind noise occure in the transformer --------
(a) zoom
(b) hum
(c) too
(d) ooo

Ans:- b
15. The highest voltage for transmitting electrical power in India is
(a) 400 kV
(6) 132 kV
(c) 33 kV
(d)  66 kV
Ans:- a

16. A Buchholz relay can be installed on
(a) oil cooled transformers
(b) air-cooled transformers
(c) sf6 transformer
(d) welding transformers
Ans:- a

17. Star/star transformers work satisfactorily when
(a) on balanced as well as unbalanced loads
(b) load is balanced only
(c) load is unbalanced only
(d) none of the above
Ans:- b

18. Noise level test in a transformer is a
(a) type test
(b) routine test
(c)  special test
(d) none of the above
Ans:- a

19. The core used in high frequency transformer is usually
(a) mild steel core
(b) air core
(c) cost iron core
(d) copper core

Ans:- b

20. The value of flux involved m the e.m.f. equation of a transformer is
(a)  instantaneous value
(b)  instantaneous value
(c) r.m.s. value
(d) maximum value
Ans:- d