Objective Type Questions

1. Energy transfer from primary side of a transformer to its secondary side is done
2. a) Through air
3. b) By the flux
4. c) Though cooling coil
5. d) None of the above
6. In a transformer, which of this one does not change?
7. a) Frequency
8. b) Voltage
9. c) Current
10. d) All of the above
11. Between a rotating machine and a transformer, name the loss that is uncommon
12. a) Hysteresis loss
13. b) Copper loss
14. c) Eddy current loss
15. d) Windage loss
16. Lamination of a transformer core is to
17. a) Reduce copper losses
18. b) Reduce hysteresis loss
19. c) Reduce eddy current losses

d)Reduce all the above losses

5. What is the percentage of full load current when the transformer draws no load current?
6. a) 12 to 15 percent
7. b) 0.2 to 0.5 percent
8. c) 20 to 30 percent
9. d) 2 to 5 percent
10. A transformer’s lamination produces certain degree of mechanical vibrations. What does it depend upon?
11. a) Size of laminations
12. b) Gauge of laminations
13. c) Tightness of clamping

d)all of the above

7. A transformer’s path of magnetic flux should definitely have
8. a) Low resistance
9. b) Low reluctance
10. c) High resistance

d)High reluctance

8. The likely chance when a transformer’s lamination has burrs on its edges
9. a) Noise
10. b) Vibrations
11. c) Higher hysteresis loss

d)Higher eddy current loss

9. In case of transformer oil, its dielectric strength is
10. a) 100 kV
11. b) 330 kV
12. c) 1 kV

d)33 kV

10. Utilization of no load test which is performed on a transformer is to find out
11. a) Magnetizingloss and current
12. b) Efficiency of the transformer
13. c) Magnetizing current
14. d) Copper loss
15. If the consideration is about cold rolled grain oriental steel, its permissible flux density will be
16. a) 1.7 Wb/m2
17. b) 2.7 Wb/m2
18. c) 3.7 Wb/m2
19. d) 4.7 Wb/m2
20. On a transformer, Sumpner’s test is done to find out
21. a) Stray losses
22. b) All day efficiency
23. c) Temperature
24. d) None of the above
25. A transformer’s efficaciousness will be the highest in
26. a) Copper losses = Eddy current losses
27. b) Iron losses = Copper losses
28. c) Hysteresis losses= Copper losses
29. d) Eddy current= losses Hysteresis losses
30. In a certain test performed on a transformer, say short circuit test, it was seen that there was a sudden hike in frequency. It was seen that the hike was from 50 HZ to 200 Hz. What will be the hike by factor (increase) of copper loss?
31. a) 4
32. b) 16
33. c) 1/4
34. d) 4
35. Iron core provision in a transformer is for the purpose
36. a) Decrease the reluctance of the magnetic path
37. b) Reduce eddy current losses
38. c) Provide support to windings
39. d) Reduce hysteresis loss
40. In transformer, no load current means
41. a) Lags behind voltage by nearly15°
42. b) Leads voltage by nearly 15°
43. c) Lags behind voltage by nearly 75°

d)Leads voltage by nearly 75°

17. On which side of a transformer is short circuited test performed
18. a) Primary side
19. b) Secondary side
20. c) High voltage side
21. d) Low voltage side
22. while installing a transformer, which of this is not the part
23. Exciter
24. Buchholz relay
25. Breather
26. Conservator
27. Higher flux density utilization in transformer design
28. Reduces copper losses
29. Reduces iron losses
30. Increases part load efficiency
31. Reduces weight per kVA
32. The toppings in any transformer is provided on

Low voltage side

Primary side

High voltage side

Secondary side

21. In a breather the utilized chemical is
22. Silica gel
23. Sodium chloride
24. Silica sand
25. Asbestos fibre
26. The quality breather chemical which is utilized in a transformer should definitely comprise of
27. Cleansing the transformer oil
28. Cooling the transformer oil
29. Absorbing moisture
30. Ionizing air
31. In case of ideal transformer, its secondary and primary inductances has unlimited value.

Yes

No

24. If supply voltage of a pump motor is 1 and 2/3rd of its voltage is what it requires to run, it will
25. Continue to run at less speed
26. Burn
27. Continue to deliver exact power
28. Stall
29. Due to the magnetic force creating vibrations of laminations a noise is produced. It is called
30. Zoom
31. Magnetostriction
32. Hum
33. Boo
34. Ratingsof an ideal transformer can be stated by
35. KVA
36. Volts
37. KW
38. Amperes
39. Transformer core is constructed withcertain materials. The common material is

aluminium

copper

silicon steel

wood

Answers

1. b
2. a
3. c
4. c
5. d
6. d
7. b
8. d
9. d
10. a
11. a
12. c
13. b
14. b
15. a
16. d
17. d
18. a
19. d
20. a
21. a
22. c
23. b
24. d
25. c
26. a
27. b

Links of Previous Main Topic:-

• Current Electricity Basic Concepts
• Introduction to Alternating Current
• Introduction Three Phase A C Circuits
• Magnetic Field
• General Aspects
• Basic Definitions Transformers

Links of Next Electrical Engineering Topics:-

• Theoretical Questions Transformers
• Elementary Theory of Ideal Transformer
• General Aspects Polyphase Induction Motors
• Single Phase Motors
• Characteristics of D C Generators
• Measuring Instruments
• Power Supply System