Starters are used with D.C. motors because
Starters are used with D.C. motors because
In a D.C. generator, the iron losses mainly take place in
In a D.C. generator, the iron losses mainly take place in
Which of the following method of speed control of D.C. machine will offer minimum efficiency?
Which of the following method of speed control of D.C. machine will offer minimum efficiency?
The direction of rotation of a D.C. series motor can be changed by
The direction of rotation of a D.C. series motor can be changed by
In the D.C. motor the iron losses occur in
In the D.C. motor the iron losses occur in
Which D.C. motor will be preferred for machine tools?
Which D.C. motor will be preferred for machine tools?
Differentially compound D.C. motors can find applications requiring
Differentially compound D.C. motors can find applications requiring
Which of the following motors is most suitable for signaling devices and many kinds of timers?
Which of the following motors is most suitable for signaling devices and many kinds of timers?
The starting resistance of a D.C. motor is generally
The starting resistance of a D.C. motor is generally
If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens
If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens
For which of the following applications a D.C. motor is preferred over an A.C. motor?
For which of the following applications a D.C. motor is preferred over an A.C. motor?
Which D.C. motor is generally preferred for cranes and hoists?
Which D.C. motor is generally preferred for cranes and hoists?
The speed of a D.C. shunt motor can be increased by
The speed of a D.C. shunt motor can be increased by
In which of the following applications D.C. series motor is invariably tried?
In which of the following applications D.C. series motor is invariably tried?
The purpose of retardation test on D.C. shunt machines is to find out
The purpose of retardation test on D.C. shunt machines is to find out
In Ward-Leonard control the lower limit of speed is imposed by
In Ward-Leonard control the lower limit of speed is imposed by
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?
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?
The power mentioned on the name plate of an electric motor indicates
The power mentioned on the name plate of an electric motor indicates
Which of the following loss in a D.C. generator is dissipated in the form of heat?
Which of the following loss in a D.C. generator is dissipated in the form of heat?
The total losses in a well designed D.C. generator of 10 kW will be nearly
The total losses in a well designed D.C. generator of 10 kW will be nearly
As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit
As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit
The speed of a D.C. motor can be varied by varying
The speed of a D.C. motor can be varied by varying
When the armature of a D.C. motor rotates, e.m.f. induced is
When the armature of a D.C. motor rotates, e.m.f. induced is
Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?
Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?
Which of the following losses are significantly reduced by laminating the core of a D.C. generator?
Which of the following losses are significantly reduced by laminating the core of a D.C. generator?
Which method of braking is generally used in elevators?
Which method of braking is generally used in elevators?
By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?
By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?
The armature torque of the D.C. shunt motor is proportional to
The armature torque of the D.C. shunt motor is proportional to
One D.C. motor drives another D.C. motor. The second D.C. motor when excited and driven
One D.C. motor drives another D.C. motor. The second D.C. motor when excited and driven
Following motor is used where high starting torque and wide speed range control is required.
Following motor is used where high starting torque and wide speed range control is required.
For which types of D.C. motor, dynamic braking is generally used?
For which types of D.C. motor, dynamic braking is generally used?
A three point starter is considered suitable for
A three point starter is considered suitable for
Which of the following motors one will choose to drive the rotary compressor?
Which of the following motors one will choose to drive the rotary compressor?
Which of the following tests will be suitable for testing two similar D.C. series motors of large capacity?
Which of the following tests will be suitable for testing two similar D.C. series motors of large capacity?
The type of D.C. motor used for shears and punches is
The type of D.C. motor used for shears and punches is
Which of the following load normally needs starting torque more than the rated torque?
Which of the following load normally needs starting torque more than the rated torque?
D.C. generators are normally designed for maximum efficiency around
D.C. generators are normally designed for maximum efficiency around
Three point starter can be used for
Three point starter can be used for
Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors?
Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors?
The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is
The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is
Why are the D.C. motors preferred for traction applications?
Why are the D.C. motors preferred for traction applications?
In a D.C. shunt motor, speed is
In a D.C. shunt motor, speed is
Which of the following motors is most suitable for signalling devices and many kinds of timers ?
Which of the following motors is most suitable for signalling devices and many kinds of timers ?
To get the speed of D.C, motor below the normal without wastage of electrical energy is used.
To get the speed of D.C, motor below the normal without wastage of electrical energy is used.
Which of the following motors is usually used in household refrigerators?
Which of the following motors is usually used in household refrigerators?
In D.C. shunt motors as load is reduced
In D.C. shunt motors as load is reduced
D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the
D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the
In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be
In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be
Speed control by Ward Leonard method gives uniform speed variation
Speed control by Ward Leonard method gives uniform speed variation
If a D.C. motor is connected across the A.C. supply it will
If a D.C. motor is connected across the A.C. supply it will
Which one of the following is not the function of pole shoes in a D.C. machine?
Which one of the following is not the function of pole shoes in a D.C. machine?
Which motor should not be started on no-load?
Which motor should not be started on no-load?
D.C. shunt motors are used for driving
D.C. shunt motors are used for driving
D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select this
D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select this
Which D.C. motor has got maximum self loading property?
Which D.C. motor has got maximum self loading property?
A direct on line starter is used: for starting motors
A direct on line starter is used: for starting motors
If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ?
If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ?
D.C. series motors are used
D.C. series motors are used
For starting a D.C. motor a starter is required because
For starting a D.C. motor a starter is required because
In D.C. machines the residual magnetism is of the order of
In D.C. machines the residual magnetism is of the order of
For the same H.P. rating and full load speed, following motor has poor starting torque
For the same H.P. rating and full load speed, following motor has poor starting torque
If a D.C. motor is to be selected for conveyors, which rioter would be preferred?
If a D.C. motor is to be selected for conveyors, which rioter would be preferred?
The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is
The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is
Ward-Leonard control is basically a
Ward-Leonard control is basically a
If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking
If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking
The hysteresis loss in a D.C. machine least depends on
The hysteresis loss in a D.C. machine least depends on
The armature voltage control of D.C. motor provides
The armature voltage control of D.C. motor provides
Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator?
Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator?
The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by
The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by
In case of conductively compensated D.C. series motors, the compensating winding is provided
In case of conductively compensated D.C. series motors, the compensating winding is provided
In a D.C. generator all of the following could be the effects of iron losses except
In a D.C. generator all of the following could be the effects of iron losses except
In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to
In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to
If I2 be the armature current, then speed of a D.C. shunt motor is
If I2 be the armature current, then speed of a D.C. shunt motor is
The plugging gives the
The plugging gives the
If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor
If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor
In D.C. machines fractional pitch winding is used
In D.C. machines fractional pitch winding is used
If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens
If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens
When two D.C. series motors are connected in parallel, the resultant speed is
When two D.C. series motors are connected in parallel, the resultant speed is
The condition for maximum efficiency for a D.C. generator is
The condition for maximum efficiency for a D.C. generator is
Which D.C. motor has got maximum self relieving property?
Which D.C. motor has got maximum self relieving property?
The main disadvantage of the Ward-Leonard control method is
The main disadvantage of the Ward-Leonard control method is
In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will
In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will
In variable speed motor
In variable speed motor
For constant torque drive which speed control method is preferred?
For constant torque drive which speed control method is preferred?
Where D.C. motor of H.P. 12 or more requires frequent starting, stopping, reversing and speed control
Where D.C. motor of H.P. 12 or more requires frequent starting, stopping, reversing and speed control
Sparking at the commutator of a D.C. motor may result in
Sparking at the commutator of a D.C. motor may result in
As the load is increased the speed of D.C. shunt motor will
As the load is increased the speed of D.C. shunt motor will
These days D.C. motors are widely used in
These days D.C. motors are widely used in
During rheostat braking of D.C. series motors
During rheostat braking of D.C. series motors
Torque developed by a D.C. motor depends upon
Torque developed by a D.C. motor depends upon
Regenerative method of braking is based on that
Regenerative method of braking is based on that
If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will
If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will
At the instant of starting when a D.C. motor is put on supply, it behaves like
At the instant of starting when a D.C. motor is put on supply, it behaves like
The current drawn by the armature of D.C. motor is directly proportional to
The current drawn by the armature of D.C. motor is directly proportional to
Which of the following motor is preferred for operation in highly explosive atmosphere?
Which of the following motor is preferred for operation in highly explosive atmosphere?
In case the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be
In case the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be
A D.C. series motor is that which
A D.C. series motor is that which
Which of the following motor has the poorest speed regulation?
Which of the following motor has the poorest speed regulation?
The speed of a D.C. series motor is
The speed of a D.C. series motor is
Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be
Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be
The ratio of starting torque to full-load torque is least in case of
The ratio of starting torque to full-load torque is least in case of
If the field of a D.C. shunt motor gets opened while motor is running
If the field of a D.C. shunt motor gets opened while motor is running
No-load speed of which of the following motor will be highest?
No-load speed of which of the following motor will be highest?
Which of the following application requires high starting torque?
Which of the following application requires high starting torque?
Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make use of
Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make use of
For a D.C. shunt motor if the excitation is changed
For a D.C. shunt motor if the excitation is changed
In a manual shunt motor starter
In a manual shunt motor starter
In case of D.C. shunt motors the speed is dependent on back e.m.f. only because
In case of D.C. shunt motors the speed is dependent on back e.m.f. only because
Hopkinson's test on D.C. machines is conducted at
Hopkinson's test on D.C. machines is conducted at
The condition for maximum power in case of D.C. motor is
The condition for maximum power in case of D.C. motor is
The speed of a D.C. shunt motor more than its full-load speed can be obtained by
The speed of a D.C. shunt motor more than its full-load speed can be obtained by
D.C. generators are installed near the load centers to reduce
D.C. generators are installed near the load centers to reduce
If the supply voltage for a D.C. motor is increased, which of the following will decrease?
If the supply voltage for a D.C. motor is increased, which of the following will decrease?
Which of the following loss in a D.C. generator varies significantly with the load current?
Which of the following loss in a D.C. generator varies significantly with the load current?
In a differentially compounded D.C. motor, if shunt field suddenly opens
In a differentially compounded D.C. motor, if shunt field suddenly opens
Usually wide and sensitive speed control is desired in case of
Usually wide and sensitive speed control is desired in case of
In D.C. motor which of the following can sustain the maximum temperature rise?
In D.C. motor which of the following can sustain the maximum temperature rise?
Which of the following law/rule can he used to determine the direction of rotation of D.C. motor?
Which of the following law/rule can he used to determine the direction of rotation of D.C. motor?
Which D.C. motor is preferred for elevators?
Which D.C. motor is preferred for elevators?
Which motor has the poorest speed control?
Which motor has the poorest speed control?
What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?
What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?
Sparking, is discouraged in a D.C. motor because
Sparking, is discouraged in a D.C. motor because
