Testing Of D.C. Machines - MCQs with answers

Testing Of D.C. Machines - MCQs with answers

Q1. Out of different methods available for testing of d.c. motors, Swinburne’s test and Hopkinson’s test are commonly used in practice on

A. Shunt generators
B. Series motors
C. Shunt motors
D. All of these

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Q2. Swinburne’s test and brake tests

A. Both are direct method of testing
B. Direct method of testing, indirect method of testing
C. Indirect method of testing, direct method of testing
D. Both are indirect method of testing

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Q3. Swinburne’s test can be performed at

A. Any load
B. Only no load
C. Only full load
D. Only half load

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Q4. While performing Swinburne’s test, the iron losses are assumed to be

A. Constant
B. Absent
C. Variable
D. None of these

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Q5. The speed in d.c. machine can be measured by using

A. Anemometer
B. Tachometer
C. Voltmeter
D. Ammeter

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Q6. While carrying out brake tests if the belt snaps, then the motor will

A. Rotate at reduced speed but in forward direction
B. Rotate at increased speed but in forward direction
C. Rotate at reduced speed but in backward direction
D. Rotate at increased speed but in backward direction

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Q7. While performing retardation tests, the machine whose test is to be taken is run at a speed which is

A. Slightly less than its rated speed
B. Equal to its rated speed
C. Slightly greater than its rated speed
D. All of these

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Q8. The rotational or stray losses includes

A. Iron losses only
B. Iron losses, friction and windage losses
C. Iron losses, copper losses, friction and windage losses
D. None of these

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Q9. The rotational losses in d.c. machines is equal to the

A. Kinetic energy of armature
B. Half of the kinetic energy of armature
C. Square of the kinetic energy of armature
D. Rate of change of kinetic energy

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Q10. In regenerative test, the supply is given to the motor

A. To account for losses
B. To drive generator
C. Both (a) and (b)
D. None of these

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Q11. The back to back test is best suited for

A. Small machines
B. Medium size machines
C. Large machines
D. All of these

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Q12. For performing Hopkinson’s test two identical machines are required which are mechanically coupled. The iron losses in the two machines

A. Can be obtained separately
B. Cannot be separated
C. Both (a) and (b)
D. None of these

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Q13. The test which can be performed on the d.c. series motor is

A. Brake test
B. Hokinson’s test
C. Swinburne’s test
D. Field test

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Q14. To perform field test on d.c. machines two motors are required. The motors used are

A. Series motors
B. One will be series motor and other will be shunt motors
C. Shunt motors
D. None of these

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Q15. The difference between field test and regenerative test is that

A. Field test requires two identical machines while regenerative test requires only one machine
B. In field test iron losses can be separated while in regenerative test it cannot
C. In field test generator output is not fed back to the motor while in regenerative test generator output is fed back to the motor
D. All of these

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Q16. The most common method used to check for shorted windings is to perform

A. Field test
B. Drop test
C. Regenerative test
D. Brake test

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