Top 350+ Solved Electrical Machine 1 MCQ Questions Answer

From 196 to 210 of 365

Q. Distribution transformers are generally designed for maximum efficiency around

a. 90% load

b. zero load

c. 25% load

d. 50% load

  • d. 50% load

Q. Which of the following property is not necessarily desirable in the material fortransformer core ?

a. Mechanical strength

b. Low hysteresis loss

c. High thermal conductivity

d. High permeability

  • c. High thermal conductivity

Q. Star/star transformers work satisfactorily when

a. load is unbalanced only

b. load is balanced only

c. on balanced as well as unbalanced loads

d. none of the above

  • b. load is balanced only

Q. Delta/star transformer works satisfactorily when

a. load is balanced only

b. load is unbalanced only

c. on balanced as well as unbalanced loads

d. none of the above

  • c. on balanced as well as unbalanced loads

Q. Buchholz's relay gives warning and protection against

a. electrical fault inside the transformer itself

b. electrical fault outside the transformer in outgoing feeder

c. for both outside and inside faults

d. none of the above

  • a. electrical fault inside the transformer itself

Q. The magnetising current of a transformer is usually small because it has

a. small air gap

b. large leakage flux

c. laminated silicon steel core

d. fewer rotating parts

  • a. small air gap

Q. Which of the following does not change in an ordinary transformer ?

a. Frequency

b. Voltage

c. Current

d. Any of the above

  • a. Frequency

Q. Which of the following properties is not necessarily desirable for the material fortransformer core ?

a. Low hysteresis loss

b. High permeability

c. High thermal conductivity

d. Adequate mechanicalstrength

  • c. High thermal conductivity

Q. The leakage flux in a transformer depends upon

a. load current

b. load current and voltage

c. load current, voltage and frequency

d. load current, voltage, frequency and powerfactor

  • a. load current

Q. The path of the magnetic flux in transformer should have

a. high reluctance

b. low reactance

c. high resistance

d. low resistance

  • b. low reactance

Q. Noise level test in a transformer is a

a. special test

b. routine test

c. type test

d. none of the above

  • c. type test

Q. Which of the foJIowing is not a routine test on transformers ?

a. Core insulation voltage test

b. Impedance test

c. Radio interference test

d. Polarity test

  • c. Radio interference test

Q. A transformer can have zero voltage regulation at

a. leading power factor

b. lagging powerfactor

c. unity power factor

d. zero power factor

  • a. leading power factor

Q. Helical coils can be used on

a. low voltage side of high kVA trans¬formers

b. high frequency transformers

c. high voltage side of small capacity transformers

d. high voltage side of high kVA rating tr

  • a. low voltage side of high kVA trans¬formers

Q. Harmonics in transformer result in

a. increased core losses

b. increased I2R losses

c. magnetic interference with communication circuits

d. all of the above

  • d. all of the above
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