Explore topic-wise MCQs in Electrical Engineering Questions.

This section includes 133 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.

1.

In a given transformer for given applied voltage, losses which remain constant irrespective of load changes are______________?
A. friction and windage losses
B. copper losses
C. hysteresis and eddy current losses
D. none of the above
Answer» D. none of the above
Discussion
2.

Which of the following loss in a transformer is zero even at full load ____________?
A. Core loss
B. Friction loss
C. Eddy current loss
D. Hysteresis loss
Answer» C. Eddy current loss
Discussion
3.

Helical coils can be used on___________________?
A. low voltage side of high kVA transformers
B. high frequency transformers
C. high voltage side of small capacity transformers
D. high voltage side of high kVA rating transformers
Answer» B. high frequency transformers
Discussion
4.

Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is_________________?
A. approximately equal to one
B. less than one
C. great than one
D. none of the above
Answer» B. less than one
Discussion
5.

A no-load test is performed on a transformer to determine_______________?
A. core loss
B. copper loss
C. efficiency
D. magnetising current
E. magnetising current and loss
Answer» F.
Discussion
6.

Losses which occur in rotating electric machines and do not occur in transformers are___________?
A. friction and windage losses
B. magnetic losses
C. hysteresis and eddy current losses
D. copper losses
Answer» B. magnetic losses
Discussion
7.

In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are__________?
A. hysteresis and eddy current losses
B. friction and windage losses
C. copper losses
D. none of the above
Answer» B. friction and windage losses
Discussion
8.

A common method of cooling a power transformer is_______________?
A. natural air cooling
B. air blast cooling
C. oil cooling
D. any of the above
Answer» D. any of the above
Discussion
9.

N atural air coo ling is generally restricted for transformers up to__________?
A. 1.5 MVA
B. 5 MVA
C. 15 MVA
D. 50 MVA
Answer» B. 5 MVA
Discussion
10.

For given applied voltage, with the increase in frequency of the applied voltage?
A. eddy current loss will decrease
B. eddy current loss will increase
C. eddy current loss will remain unchanged
D. none of the above
Answer» D. none of the above
Discussion
11.

Which of the following protection is normally not provided on small distribution transformers ?
A. Overfluxing protection
B. Buchholz relay
C. Overcurrent protection
D. All of the above
Answer» C. Overcurrent protection
Discussion
12.

Which of the following acts as a protection against high voltage surges due to lightning and switching ?
A. Horn gaps
B. Thermal overload relays
C. Breather
D. Conservator
Answer» B. Thermal overload relays
Discussion
13.

A good voltage regulation of a transformer means________________?
A. output voltage fluctuation from no load to full load is least
B. output voltage fluctuation with power factor is least
C. difference between primary and secondary voltage is least
D. difference between primary and secondary voltage is maximum
Answer» B. output voltage fluctuation with power factor is least
Discussion
14.

For a transformer, operating at constant load current, maximum efficiency will occur at______________?
A. 0.8 leading power factor
B. 0.8 lagging power factor
C. zero power factor
D. unity power factor
Answer» E.
Discussion
15.

A Transformer transforms____________?
A. voltage
B. current
C. current and voltage
D. power
Answer» E.
Discussion
16.

A transformer can have regulation closer to zero___________?
A. on full-load
B. on overload
C. on leading power factor
D. on zero power factor
Answer» D. on zero power factor
Discussion
17.

The secondary of a current transformer is always short-circuited under operating conditions because it____________________?
A. avoids core saturation and high voltage induction
B. is safe to human beings
C. protects the primary circuit
D. none of the above
Answer» B. is safe to human beings
Discussion
18.

In a transformer the resistance between its primary and secondary should be_____________?
A. zero
B. 10 Q
C. 1000 Q
D. infinity
Answer» E.
Discussion
19.

A shell-type transformer has_________?
A. high eddy current losses
B. reduced magnetic leakage
C. negligibly hysteresis losses
D. none of the above
Answer» C. negligibly hysteresis losses
Discussion
20.

Which of the following insulating materials can withstand the highest temperature safely ?
A. Cellulose
B. Asbestos
C. Mica
D. Glass fibre
Answer» D. Glass fibre
Discussion
21.

The efficiency of two identical transformers under load conditions can be determined by_______________?
A. short-circuit test
B. back-to-back test
C. open circuit test
D. any of the above
Answer» C. open circuit test
Discussion
22.

In a power or distribution transformer about 10 per cent end turns are heavily insulated__________?
A. to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns
B. to absorb the line surge voltage and save the winding of transformer from damage
C. to reflect the line surge and save the winding of a transformer from damage
D. none of the above
Answer» B. to absorb the line surge voltage and save the winding of transformer from damage
Discussion
23.

Reduction in core losses and increase in permeability are obtained with transformer employing__________?
A. core built-up of laminations of cold rolled grain oriented steel
B. core built-up of laminations of hot rolled sheet
C. either of the above
D. none of the above
Answer» B. core built-up of laminations of hot rolled sheet
Discussion
24.

Which of the following parts of a transformer is visible from outside ?
A. Bushings
B. Core
C. Primary winding
D. Secondary winding
Answer» B. Core
Discussion
25.

The noise produced by a transformer is termed as_______________________?
A. zoom
B. hum
C. ringing
D. buzz
Answer» C. ringing
Discussion
26.

Open circuit test on transformers is conducted to determine____________?
A. hysteresis losses
B. copper losses
C. core losses
D. eddy current losses
Answer» D. eddy current losses
Discussion
27.

The voltage transformation ratio of a transformer is equal to the ratio of_______________?
A. primary turns to secondary turns
B. secondary current to primary current
C. secondary induced e.m.f. to primary induced e.m.f
D. secondary terminal voltage to primary applied voltage
Answer» D. secondary terminal voltage to primary applied voltage
Discussion
28.

The no load current in a transformer lags behind the applied voltage by an angle of about_____________?
A. 180°
B. 120″
C. 90°
D. 75°
Answer» D. 75°
Discussion
29.

Efficiency of a power transformer is of the order of________________?
A. 100 per cent
B. 98 per cent
C. 50 per cent
D. 25 per cent
Answer» C. 50 per cent
Discussion
30.

Natural oil cooling is used for transformers up to a rating of____________?
A. 3000 kVA
B. 1000 kVA
C. 500 kVA
D. 250 kVA
Answer» B. 1000 kVA
Discussion
31.

The purpose of providing iron core in a step-up transformer is?
A. to provide coupling between primary and secondary
B. to increase the magnitude of mutual flux
C. to decrease the magnitude of mag-netizing current
D. to provide all above features
Answer» E.
Discussion
32.

Which winding in a transformer has more number of turns ?
A. Low voltage winding
B. High voltage winding
C. Primary winding
D. Secondary winding
Answer» C. Primary winding
Discussion
33.

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
Answer» D. none of the above
Discussion
34.

A transformer transforms__________________?
A. voltage
B. current
C. power
D. frequency
Answer» D. frequency
Discussion
35.

A transformer cannot raise or lower the voltage of a D.C. supply because_______________?
A. there is no need to change the D.C. voltage
B. a D.C. circuit has more losses
C. Faraday’s laws of electromagnetic induction are not valid since the rate of change of flux is zero
D. none of the above
Answer» D. none of the above
Discussion
36.

The chemical used in breather is_______________?
A. asbestos fiber
B. silica sand
C. sodium chloride
D. silica gel
Answer» E.
Discussion
37.

An ideal transformer has infinite values of primary and secondary inductances. The statement is______________?
A. true
B. false
Answer» C.
Discussion
38.

The chemical used in breather for transformer should have the quality of____________?
A. ionizing air
B. absorbing moisture
C. cleansing the transformer oil
D. cooling the transformer oil
Answer» C. cleansing the transformer oil
Discussion
39.

The use of higher flux density in the transformer design____________?
A. reduces weight per kVA
B. reduces iron losses
C. reduces copper losses
D. increases part load efficiency
Answer» B. reduces iron losses
Discussion
40.

In a transformer the tappings are generally provided on_____________?
A. primary side
B. secondary side
C. low voltage side
D. high voltage side
Answer» E.
Discussion
41.

What will happen if the transformers working in parallel are not connected with regard to polarity ?
A. The power factor of the two trans-formers will be different from the power factor of common load
B. Incorrect polarity will result in dead short circuit
C. The transformers will not share load in proportion to their kVA ratings
D. none of the above
Answer» C. The transformers will not share load in proportion to their kVA ratings
Discussion
42.

If R2 is the resistance of secondary winding of the transformer and K is the transformation ratio then the equivalent secondary resistance referred to primary will be___________?
A. R2/VK
B. R2IK2
C. R22
D. R22/K
Answer» C. R22
Discussion
43.

If the percentage impedances of the two transformers working in parallel are different, then______________________?
A. transformers will be overheated
B. power factors of both the transformers will be same
C. parallel operation will be not possible
D. parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the
Answer» E.
Discussion
44.

The power transformer is a constant______________?
A. voltage device
B. current device
C. power device
D. main flux device
Answer» E.
Discussion
45.

Two transformers operating in parallel will share the load depending upon their____________?
A. leakage reactance
B. per unit impedance
C. efficiencies
D. ratings
Answer» C. efficiencies
Discussion
46.

Greater the secondary leakage flux____________?
A. less will be the secondary induced e.m.f.
B. less will be the primary induced e.m.f.
C. less will be the primary terminal voltage
D. none of the above
Answer» B. less will be the primary induced e.m.f.
Discussion
47.

Spacers are provided between adjacent coils?
A. to provide free passage to the cooling oil
B. to insulate the coils from each other
C. both A. and (b)
D. none of the above
Answer» B. to insulate the coils from each other
Discussion
48.

No-load current of a transformer has_____________?
A. has high magnitude and low power factor
B. has high magnitude and high power factor
C. has small magnitude and high power factor
D. has small magnitude and low power factor
Answer» E.
Discussion
49.

Transformer breaths in when_______________?
A. load on it increases
B. load on it decreases
C. load remains constant
D. none of the above
Answer» C. load remains constant
Discussion
50.

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
Answer» C. at 80% full load
Discussion