Losses In D.C. Machines - MCQs with answers

Losses In D.C. Machines - MCQs with answers

Q1. Iron losses are considered to be the constant losses. It depends on
A. Voltage
B. Frequency
C. Both (a) and (b)
D. None of these

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Q2. Copper losses in a rotating machine is

A. Variable losses
B. Constant losses
C. Either (a) or (b)
D. None of these

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Q3. Stray losses are the losses which vary with the load but their relationship with load current cannot be identified. Stay losses is maximum in

A. Synchronous machines
B. D.C. machines
C. Induction machines
D. Equal in all types of machines

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Q4. The brush contact losses in a d.c. machine is

A. Inversely proportional to the square of current
B. Directly proportional to the square of current
C. Inversely proportional to the current
D. Directly proportional to the current

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Q5. Electrical power output in a d.c. generator is equal to

A. Electrical power developed in armature – copper losses
B. Mechanical power input – iron and friction losses
C. Electrical power developed in armature – iron and copper losses
D. Mechanical power input – iron and friction losses – copper losses

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Q6. Mechanical power developed in armature of a d.c. motor is given by

A. Electrical power input to motor – copper losses
B. Motor output + iron and friction losses
C. Both (a) & (b)
D. None of these

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Q7. Out of electrical, mechanical and magnetic losses, the losses which is minimum is

A. All are equal
B. Electrical losses
C. Magnetic losses
D. Mechanical losses

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Q8. The hysteresis motor are mainly used in tape recorders because

A. Of its extremely steady torque
B. Constant speed
C. Reduced initial current
D. None of these

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