1.
A transformer transforms
a) Voltage
b) Current
c) Power
d) Frequency
2. Which of the following does not change in a transformer?
a) Current
b) Voltage
c) Frequency
d) All of the Above
3. 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 voltage or high voltage winding
d) None of the above
4. 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
5. Which winding in a transformer has more number of turns?
a) Low voltage winding
b) High voltage winding
c) Primary winding
d) Secondary winding
6. A common method of cooling power transformer is
a) Natural air cooling
b) Air blast cooling
c) Oil cooling
d) None of above
7. The power transformer is a constant
a) Voltage device
b) Current device
c) Power device
d) Main flux device
8. In a transformer the tapping are generally provided on
a) Primary side
b) Secondary side
c) Low voltage side
d) High voltage side
9. The transformer rating are usually expressed in terms of
a) Volts
b) Amperes
c) kW
d) kVA
10. Material used for construction of transformer core is usually
a) Wood
b) Copper
c) Aluminum
d) Silicon steel
11. The thickness of laminations used in a transformer is usually
a) 0.4 mm to 0.5 mm
b) 4 mm to 5 mm
c) 14 mm to 15 mm
d) 25 mm to 40 mm
12. In a transformer the resistance between its primary and secondary is
a) Zero
b) 1 ohm
c) 1000 ohms
d) Infinite
13. Transformer oil must be free from
a) Sludge
b) Odour
c) Gases
d) Moisture
14. 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
15. Delta / star transformer works satisfactorily when
a) Load is balanced only
b) Load is unbalanced only
c) On balanced as well as unbalanced only
d) None of the above
16. Which of the following does not change in an ordinary transformer?
a) Frequency
b) Voltage
c) Current
d) None of the above
17. A step up transformer increase
a) Voltage
b) Current
c) Power
d) Frequency
18. Silicon steel used in lamination mainly reduces
a) Hysteresis loss
b) Eddy current losses
c) Copper losses
d) All of the above
19. An ideal transformer is one which has
a) No losses and magnetic leakage
b) Interleaved primary and secondary windings
c) A common core for its primary and secondary windings
d) Core of stainless steel and winding of pure copper metal
20. An ideal transformer will have maximum efficiency at a load such that
a) Copper loss= Iron loss
b) Copper loss<Iron loss
c) Copper loss> Iron loss
d) None of the above
21. If the supply frequency to the transformer is increased the iron loss will
a) Not increase
b) Decrease
c) Increase
d) None of the above
22. Iron loss a transformer can be measure by
a) Low power factor wattmeter
b) Unity power factor wattmeter
c) Frequency meter
d) None of the above
23. During open circuit test of a transformer
a) Primary is supplied rated voltage
b) Primary is supplied full load current
c) Primary is supplied current at reduced voltage
d) Primary is supplied rated kVA
24. Open circuit test on transformer is conducted to determine
a) Hysteresis losses
b) Copper losses
c) Core losses
d) Eddy current losses
25. Short circuit test on transformer is conducted to determine
a) Hysteresis losses
b) Copper losses
c) Core losses
d) Eddy current losses
26. The noise produced by a transformer is termed as
a) Zoom
b) Hum
c) Ringing
d) Buzz
27. Which of the following loss in a transformer is zero even at full load?
a) Core loss
b) Friction loss
c) Hysteresis losses
d) Eddy current losses
28. The all-day efficiency of a transformer depends primarily on
a) Its copper loss
b) The amount of load
c) The duration of load
d) Both (b) & (c)
29. Transformer are rated in kVA instead of KW because
a) Load power factor is often not known
b) KVA is fixed whereas KW depends on load power factor
c) Total transformer loss depends on volt-ampere
d) It has become customary
30. Which of the following is not the basic element of transformer?
a) Core
b) Primary winding
c) Secondary wining
d) Mutual flux
31. The degree of mechanical vibrations produced by the laminations of a transformer depends on
a) Tightness of clamping
b) Gauge of lamination
c) Size of lamination
d) All of the above
32. No-load on a transformer is carried out to determine
a) Copper loss
b) Magnetizing current
c) Magnetizing current and loss
d) Efficiency of the transformer
33. The dielectric strength of transformer oil is expected to be
a) 1kV
b) 33kV
c) 100kV
d) 330kV
34. Sumpner’s test is conducted on transformer to determine
a) Temperature
b) Stray losses
c) All- day efficiency
d) None of the above
35. No- load current in a transformer
a) Lags behind the voltage by about 750
b) Leads the voltage by about 750
c) Lags behind the voltage by about 150
d) Leads the voltage by about 150
36. The purpose of providing an iron core in a transformer is to
a) Provide support to winding
b) Reduce hysteresis loss
c) Decrease the reluctance of the magnetic path
d) Reduce eddy current losses
37. Transformer breaths in when
a) Load on it increases
b) Load on it decrease
c) Load remain constant
d) None of the above
38. No- load current of a transformer has
a) High magnitude and low power factor
b) High magnitude and high power factor
c) Small magnitude and high power
d) Small magnitude and low power factor
39. Spacers are provided between adjacent coils to
a) Provide free passage to the cooling oil
b) Insulate the coils from each other
c) Both (a) & (b)
d) None of the above
a) Voltage
b) Current
c) Power
d) Frequency
2. Which of the following does not change in a transformer?
a) Current
b) Voltage
c) Frequency
d) All of the Above
3. 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 voltage or high voltage winding
d) None of the above
4. 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
5. Which winding in a transformer has more number of turns?
a) Low voltage winding
b) High voltage winding
c) Primary winding
d) Secondary winding
6. A common method of cooling power transformer is
a) Natural air cooling
b) Air blast cooling
c) Oil cooling
d) None of above
7. The power transformer is a constant
a) Voltage device
b) Current device
c) Power device
d) Main flux device
8. In a transformer the tapping are generally provided on
a) Primary side
b) Secondary side
c) Low voltage side
d) High voltage side
9. The transformer rating are usually expressed in terms of
a) Volts
b) Amperes
c) kW
d) kVA
10. Material used for construction of transformer core is usually
a) Wood
b) Copper
c) Aluminum
d) Silicon steel
11. The thickness of laminations used in a transformer is usually
a) 0.4 mm to 0.5 mm
b) 4 mm to 5 mm
c) 14 mm to 15 mm
d) 25 mm to 40 mm
12. In a transformer the resistance between its primary and secondary is
a) Zero
b) 1 ohm
c) 1000 ohms
d) Infinite
13. Transformer oil must be free from
a) Sludge
b) Odour
c) Gases
d) Moisture
14. 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
15. Delta / star transformer works satisfactorily when
a) Load is balanced only
b) Load is unbalanced only
c) On balanced as well as unbalanced only
d) None of the above
16. Which of the following does not change in an ordinary transformer?
a) Frequency
b) Voltage
c) Current
d) None of the above
17. A step up transformer increase
a) Voltage
b) Current
c) Power
d) Frequency
18. Silicon steel used in lamination mainly reduces
a) Hysteresis loss
b) Eddy current losses
c) Copper losses
d) All of the above
19. An ideal transformer is one which has
a) No losses and magnetic leakage
b) Interleaved primary and secondary windings
c) A common core for its primary and secondary windings
d) Core of stainless steel and winding of pure copper metal
20. An ideal transformer will have maximum efficiency at a load such that
a) Copper loss= Iron loss
b) Copper loss<Iron loss
c) Copper loss> Iron loss
d) None of the above
21. If the supply frequency to the transformer is increased the iron loss will
a) Not increase
b) Decrease
c) Increase
d) None of the above
22. Iron loss a transformer can be measure by
a) Low power factor wattmeter
b) Unity power factor wattmeter
c) Frequency meter
d) None of the above
23. During open circuit test of a transformer
a) Primary is supplied rated voltage
b) Primary is supplied full load current
c) Primary is supplied current at reduced voltage
d) Primary is supplied rated kVA
24. Open circuit test on transformer is conducted to determine
a) Hysteresis losses
b) Copper losses
c) Core losses
d) Eddy current losses
25. Short circuit test on transformer is conducted to determine
a) Hysteresis losses
b) Copper losses
c) Core losses
d) Eddy current losses
26. The noise produced by a transformer is termed as
a) Zoom
b) Hum
c) Ringing
d) Buzz
27. Which of the following loss in a transformer is zero even at full load?
a) Core loss
b) Friction loss
c) Hysteresis losses
d) Eddy current losses
28. The all-day efficiency of a transformer depends primarily on
a) Its copper loss
b) The amount of load
c) The duration of load
d) Both (b) & (c)
29. Transformer are rated in kVA instead of KW because
a) Load power factor is often not known
b) KVA is fixed whereas KW depends on load power factor
c) Total transformer loss depends on volt-ampere
d) It has become customary
30. Which of the following is not the basic element of transformer?
a) Core
b) Primary winding
c) Secondary wining
d) Mutual flux
31. The degree of mechanical vibrations produced by the laminations of a transformer depends on
a) Tightness of clamping
b) Gauge of lamination
c) Size of lamination
d) All of the above
32. No-load on a transformer is carried out to determine
a) Copper loss
b) Magnetizing current
c) Magnetizing current and loss
d) Efficiency of the transformer
33. The dielectric strength of transformer oil is expected to be
a) 1kV
b) 33kV
c) 100kV
d) 330kV
34. Sumpner’s test is conducted on transformer to determine
a) Temperature
b) Stray losses
c) All- day efficiency
d) None of the above
35. No- load current in a transformer
a) Lags behind the voltage by about 750
b) Leads the voltage by about 750
c) Lags behind the voltage by about 150
d) Leads the voltage by about 150
36. The purpose of providing an iron core in a transformer is to
a) Provide support to winding
b) Reduce hysteresis loss
c) Decrease the reluctance of the magnetic path
d) Reduce eddy current losses
37. Transformer breaths in when
a) Load on it increases
b) Load on it decrease
c) Load remain constant
d) None of the above
38. No- load current of a transformer has
a) High magnitude and low power factor
b) High magnitude and high power factor
c) Small magnitude and high power
d) Small magnitude and low power factor
39. Spacers are provided between adjacent coils to
a) Provide free passage to the cooling oil
b) Insulate the coils from each other
c) Both (a) & (b)
d) None of the above
Tags:
electrical-eng-quiz