Explore topic-wise MCQs in Electrical Machines.

This section includes 20 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Machines knowledge and support exam preparation. Choose a topic below to get started.

1.

The efficiency of a transformer can be calculated accurately from ___________

A. Open circuit test, Short circuit test
B. Open circuit test, Short circuit test, Sumpner’s test
C. Sumpner’s test
D. load test
Answer» B. Open circuit test, Short circuit test, Sumpner’s test
Discussion
2.

From the above graph of the core losses per cycle is, the eddy losses per phase for a transformer at a operating frequency of 40 Hz is?

A. 15 W
B. 20W
C. 35W
D. 32W
Answer» B. 20W
Discussion
3.

From the above graph of the core losses per cycle is, the hysteresis losses per phase for a transformer at a operating frequency of 40 Hz is?

A. 20W
B. 30W
C. 80W
D. 32W
Answer» B. 30W
Discussion
4.

The full load voltage drop in a 1-phase transformer is 2% and 4% respectively due to resistance and leakage reactance. Then the voltage drop is zero at __________

A. 0.45 lagging
B. 0.45 leading
C. 0.9 lagging
D. 0.9 leading
Answer» D. 0.9 leading
Discussion
5.

The full load voltage drop in a 1-phase transformer is 2% and 4% respectively due to resistance and leakage reactance. Then the voltage drop is maximum at __________

A. 0.45 lagging
B. 0.45 leading
C. 0.9 lagging
D. 0.9 leading
Answer» B. 0.45 leading
Discussion
6.

The load current at which maximum efficiency occurs is independent of the load power factor.

A. True
B. False
Answer» C.
Discussion
7.

The efficiency of a 20 KVA, 2000/200 V, single phase transformer at unity pf is 98%. The given total losses at full load is 200 W. The pu resistance is?

A. 0.01
B. 0.1
C. 1.0
D. 0.0196
Answer» B. 0.1
Discussion
8.

The efficiency of a 20 KVA, 2000/200 V, single phase transformer at unity pf is 98%. The total losses at this condition is?

A. 408W
B. 4.08kW
C. 204W
D. 2.04kW
Answer» B. 4.08kW
Discussion
9.

It is possible to attain maximum efficiency in a transformer when the ______

A. core losses are equal to rated full load copper losses
B. core losses are more than rated full load copper losses
C. core losses and full load copper losses are constant
D. copper loss also becomes constant
Answer» B. core losses are more than rated full load copper losses
Discussion
10.

Which of the following mentioned losses occur in a transformer?

A. Hysteresis losses; Eddy current losses; Dielectric losses; Stray load losses
B. Hysteresis losses; Eddy current losses;
C. Dielectric losses; Stray load losses
D. Hysteresis losses; Eddy current losses; Stray load losses
Answer» B. Hysteresis losses; Eddy current losses;
Discussion
11.

Which of the statements made here are incorrect regarding the transformer?

A. I,III
B. II,IV
C. 1,III
D. I,IV,IIIView Answer
Answer» B. II,IV
Discussion
12.

Which of the statements made here are correct regarding the transformer?

A. I, III
B. II, IV
C. 1, III
D. I, IV, IIIView Answer
Answer» C. 1, III
Discussion
13.

THE_EFFICIENCY_OF_A_20_KVA,_2000/200_V,_SINGLE_PHASE_TRANSFORMER_AT_UNITY_PF_IS_98%._THE_GIVEN_TOTAL_LOSSES_AT_FULL_LOAD_IS_200_W._THE_PU_RESISTANCE_IS?$

A. 0.01
B. 0.1
C. 1.0
D. 0.0196
Answer» B. 0.1
Discussion
14.

The load current at which maximum efficiency occurs is independent of the load power factor.$

A. True
B. False
Answer» C.
Discussion
15.

The efficiency of a transformer can be calculated accurately from

A. Open circuit test, Short circuit test
B. Open circuit test, Short circuit test, Sumpner’s test
C. Sumpner’s test
D. load test
Answer» B. Open circuit test, Short circuit test, Sumpner‚Äö√Ñ√∂‚àö√ë‚àö¬•s test
Discussion
16.

The full load voltage drop in a 1-phase transformer is 2% and 4% respectively due to resistance and leakage reactance. Then the voltage drop is zero at

A. 0.45 lagging
B. 0.45 leading
C. 0.9 lagging
D. 0.9 leading
Answer» D. 0.9 leading
Discussion
17.

The efficiency of a 20 KVA, 2000/200 V, single phase transformer at unity pf is 98%. The the total losses at this condition i?

A. 408W
B. 4.08kW
C. 204W
D. 2.04kW
Answer» B. 4.08kW
Discussion
18.

It is possible to attain maximum efficiency in a transformer when the

A. core losses are equal to rated full load copper losses
B. core losses are more than rated full load copper losses
C. core losses and full load copper losses are constant
D. copper loss also becomes constant
Answer» B. core losses are more than rated full load copper losses
Discussion
19.

Mutual flux ______ at the lagging loading and it _____ at the leading power factor.

A. decreases, increases
B. increases,increases
C. decreases, decreases
D. increases, decreases
Answer» B. increases,increases
Discussion
20.

Which of the below mentioned losses occur in a transformer?

A. Hysteresis losses ;Eddy current losses; Dielectric losses; Stray load losses
B. Hysteresis losses ;Eddy current losses;
C. Dielectric losses; Stray load losses
D. Hysteresis losses ;Eddy current losses; Stray load losses
Answer» B. Hysteresis losses ;Eddy current losses;
Discussion