Question 1

The main disadvantage of the Ward-Leonard control method is

Accepted Answer

A) high initial cost 
B) high maintenance cost 
C) low efficiency at Hght loads 
D) all of the above 
A) high initial cost 
B) high maintenance cost 
C) low efficiency at Hght loads 
D) all of the above D

Question 2

If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking

Accepted Answer

A) regenerative 
B) plugging 
C) dynamic braking 
D) none of the above 
A) regenerative 
B) plugging 
C) dynamic braking 
D) none of the above B

Question 3

Which of the following motors is most suitable for signalling devices and many kinds of timers ?

Accepted Answer

A) D.C. shunt motor 
B) D.C. series motor 
C) Induction motor 
D) Reluctance motor 
A) D.C. shunt motor 
B) D.C. series motor 
C) Induction motor 
D) Reluctance motor D

Question 4

Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator ?

Accepted Answer

A) Providing laminations in armature core 
B) Providing laminations in stator 
C) Using non-magnetic material for frame 
D) Using material of low hysteresis co-efficient for armature core material 
A) Providing laminations in armature core 
B) Providing laminations in stator 
C) Using non-magnetic material for frame 
D) Using material of low hysteresis co-efficient for armature core material

Question 5

The losses occurring in a D.C. generator are given below. Which loss is likely to have highest proportion at rated load of the generator ?

Accepted Answer

A) hysteresis loss 
B) field copper loss 
C) armature copper loss 
D) eddy current loss 
A) hysteresis loss 
B) field copper loss 
C) armature copper loss 
D) eddy current loss

Question 6

For constant torque drive which speed control method is preferred ?

Accepted Answer

A) Field control 
B) Armature voltage control 
C) Shunt armature control 
D) Mechanical loading system 
A) Field control 
B) Armature voltage control 
C) Shunt armature control 
D) Mechanical loading system

Question 7

Which of the following loss in a D.C. generator varies significantly with the load current ?

Accepted Answer

A) Field copper loss 
B) Windage loss 
C) Armature copper loss 
D) None of the above 
A) Field copper loss 
B) Windage loss 
C) Armature copper loss 
D) None of the above

Question 8

If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will

Accepted Answer

A) increase 
B) decrease 
C) remain same 
D) become zero 
A) increase 
B) decrease 
C) remain same 
D) become zero

Question 9

Which motor should not be started on no-load ?

Accepted Answer

A) Series motor 
B) Shunt motor 
C) Cumulatively compounded motor 
D) Differentially compounded motor. 
A) Series motor 
B) Shunt motor 
C) Cumulatively compounded motor 
D) Differentially compounded motor.

Question 10

The total losses in a well designed D.C. generator of 10 kW will be nearly

Accepted Answer

A) 100 W 
B) 500 W 
C) 1000 W 
D) 1500 W 
A) 100 W 
B) 500 W 
C) 1000 W 
D) 1500 W

Question 11

The hysteresis loss in a D.C. machine least depends on

Accepted Answer

A) Frequency of magnetic reversals 
B) Maximum value of flux density 
C) Volume and grade of iron 
D) Rate of flow of ventilating air 
A) Frequency of magnetic reversals 
B) Maximum value of flux density 
C) Volume and grade of iron 
D) Rate of flow of ventilating air

Question 12

The armature voltage control of D.C. motor provides

Accepted Answer

A) constant voltage drive 
B) constant current drive 
C) constant torque drive 
D) none of the above 
A) constant voltage drive 
B) constant current drive 
C) constant torque drive 
D) none of the above

Question 13

Which of the following loss in a D.C. generator is dissipated in the form of heat?

Accepted Answer

A) Mechanical loss 
B) Core loss 
C) Copper loss 
D) All of the above 
A) Mechanical loss 
B) Core loss 
C) Copper loss 
D) All of the above

Question 14

In Ward-Leonard control the lower limit of speed is imposed by

Accepted Answer

A) residual magnetism of the generator 
B) core losses of motor 
C) mechanical losses of motor and gen¬erator together 
D) all of the above 
A) residual magnetism of the generator 
B) core losses of motor 
C) mechanical losses of motor and gen¬erator together 
D) all of the above

Question 15

The plugging gives the

Accepted Answer

A) zero torque braking 
B) smallest torque braking 
C) highest torque braking 
D) none of the above 
A) zero torque braking 
B) smallest torque braking 
C) highest torque braking 
D) none of the above

Question 16

Which of the following motors one will choose to drive the rotary compressor ?

Accepted Answer

A) D.C. shunt motor 
B) D.C. series motor 
C) Universal motor 
D) Synchronous motor 
A) D.C. shunt motor 
B) D.C. series motor 
C) Universal motor 
D) Synchronous motor

Question 17

Torque developed by a D.C. motor depends upon

Accepted Answer

A) magnetic field 
B) active length of the conductor 
C) current flow through the conductors 
D) all above factors 
A) magnetic field 
B) active length of the conductor 
C) current flow through the conductors 
D) all above factors

Question 18

Which of the following losses are significantly reduced by laminating the core of a D.C. generator ?

Accepted Answer

A) Hysteresis losses 
B) Eddy current losses 
C) Copper losses 
D) Windage losses 
A) Hysteresis losses 
B) Eddy current losses 
C) Copper losses 
D) Windage losses

Question 19

Regenerative method of braking is based on that

Accepted Answer

A) back e.m.f. is less than the applied voltage 
B) back e.m.f. is equal to the applied voltage 
C) back e.m.f. of rotor is more than the applied voltage 
D) none of the above 
A) back e.m.f. is less than the applied voltage 
B) back e.m.f. is equal to the applied voltage 
C) back e.m.f. of rotor is more than the applied voltage 
D) none of the above

Question 20

Which of the following motors is usually used in house-hold refrigerators ?

Accepted Answer

A) D.C. shunt motor 
B) D.C. series motor 
C) Single phase induction motor (split phase start or induction run motor) 
D) Reluctance motor 
A) D.C. shunt motor 
B) D.C. series motor 
C) Single phase induction motor (split phase start or induction run motor) 
D) Reluctance motor

The main disadvantage of the Ward-Leonard control method is

If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking

Which of the following motors is most suitable for signalling devices and many kinds of timers ?

Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator ?

The losses occurring in a D.C. generator are given below. Which loss is likely to have highest proportion at rated load of the generator ?

For constant torque drive which speed control method is preferred ?

Which of the following loss in a D.C. generator varies significantly with the load current ?

If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will

Which motor should not be started on no-load ?

The total losses in a well designed D.C. generator of 10 kW will be nearly

The hysteresis loss in a D.C. machine least depends on

The armature voltage control of D.C. motor provides

Which of the following loss in a D.C. generator is dissipated in the form of heat?

In Ward-Leonard control the lower limit of speed is imposed by

The plugging gives the

Which of the following motors one will choose to drive the rotary compressor ?

Torque developed by a D.C. motor depends upon

Which of the following losses are significantly reduced by laminating the core of a D.C. generator ?

Regenerative method of braking is based on that

Which of the following motors is usually used in house-hold refrigerators ?

D.C. Motors and Their Applications

D.C. Motors

D.C. Motors and Speed Control

D.C. Generator and Motor Efficiency, Testing and Braking Techniques

Filters

Exam 4: D.C. Motors and Generators

The main disadvantage of the Ward-Leonard control method is

If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking

Which of the following motors is most suitable for signalling devices and many kinds of timers ?

Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator ?

The losses occurring in a D.C. generator are given below. Which loss is likely to have highest proportion at rated load of the generator ?

For constant torque drive which speed control method is preferred ?

Which of the following loss in a D.C. generator varies significantly with the load current ?

If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will

Which motor should not be started on no-load ?

The total losses in a well designed D.C. generator of 10 kW will be nearly

The hysteresis loss in a D.C. machine least depends on

The armature voltage control of D.C. motor provides

Which of the following loss in a D.C. generator is dissipated in the form of heat?

In Ward-Leonard control the lower limit of speed is imposed by

The plugging gives the

Which of the following motors one will choose to drive the rotary compressor ?

Torque developed by a D.C. motor depends upon

Which of the following losses are significantly reduced by laminating the core of a D.C. generator ?

Regenerative method of braking is based on that

Which of the following motors is usually used in house-hold refrigerators ?

D.C. Motors and Their Applications

D.C. Motors

D.C. Motors and Speed Control

D.C. Generator and Motor Efficiency, Testing and Braking Techniques

Filters