No-load speed of which of the following motor will be highest ?

The direction of rotation of a D.C. series motor can be changed by

Which of the following application requires high starting torque ?

If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ?

Which D.C. motor will be preferred for machine tools ?

Differentially compound D.C. motors can find applications requiring

Which D.C. motor is preferred for elevators ?

If the field of a D.C. shunt motor gets opened while motor is running

Starters are used with D.C. motors because

In D.C. shunt motors as load is reduced

A D.C. series motor is that which

For starting a D.C. motor a starter is required because

The type of D.C. motor used for shears and punches is

If a D.C. motor is connected across the A.C. supply it will

To get the speed of D.C, motor below the normal without wastage of electrical energy is used.

When two D.C. series motors are connected in parallel, the resultant speed is

The speed of a D.C. shunt motor more than its full-load speed can be obtained by

In a D.C. shunt motor, speed is

A direct on line starter is used: for starting motors

What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?

In case of D.C. shunt motors the speed is dependent on back e.m.f. only because

In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be

These days D.C. motors are widely used in

By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?

In which of the following applications D.C. series motor is invariably tried?

In D.C. machines fractional pitch winding is used

A three point starter is considered suitable for

In case-the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be

The ratio of starting torque to full-load torque is least in case of

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 load normally needs starting torque more than the rated torque?

The starting resistance of a D.C. motor is generally

The speed of a D.C. series motor is

In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal o

The current drawn by the armature of D.C. motor is directly proportional to

The power mentioned on the name plate of an electric motor indicates

Which D.C. motor has got maximum self loading property?

Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?

D.C. series motors are used

For the same H.P. rating and full load speed, following motor has poor starting torque

Sparking at the commutator of a D.C. motor may result in

Which of the following motor is preferred for operation in highly explosive atmosphere ?

If the supply voltage for a D.C. motor is increased, which of the following will decrease ?

Which one of the following is not the function of pole shoes in a D.C. machine ?

The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is

The condition for maximum power in case of D.C. motor is

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 ?

Three point starter can be used for

Sparking, is discouraged in a D.C. motor because

Speed control by Ward Leonard method gives uniform speed variation

Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be

Following motor is used where high starting torque and wide speed range control is required.

In a differentially compounded D.C. motor, if shunt field suddenly opens

Which of the following motor has the poorest speed regulation ?

Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make use of

As -the load is increased the speed of D.C. shunt motor will

The armature torque of the D.C. shunt motor is proportional to

Which of the following method of speed control of D.C. machine will offer minimum efficiency ?

Usually wide and sensitive speed control is desired in case of

The armature voltage control of D.C. motor provides

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. shunt motor can be increased by

If I2 be the armature current, then speed of a D.C. shunt motor is

The speed of a D.C. motor can be varied by varying

Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors ?

For a D.C. shunt motor if the excitation is changed

Which motor has the poorest speed control?

The plugging gives the

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

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

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

Why are the D.C. motors preferred for traction applications ?

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

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

Which motor should not be started on no-load ?

Ward-Leonard control is basically a

For constant torque drive which speed control method is preferred ?

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

The main disadvantage of the Ward-Leonard control method is

Regenerative method of braking is based on that

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

In a D.C. generator all of the following could be the effects of iron losses except

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 ?

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

D.C. shunt motors are used for driving

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

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

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

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

. The condition for maximum efficiency for a D.C. generator is

. D.C. generators are normally designed for maximum efficiency around

. In a D.C. generator, the iron losses mainly take place in

. D.C. generators are installed near the load centres to reduce

. The purpose of retardation test on D.C. shunt machines is to find out

. Which of the following tests will be suitable for testing two similar D.C. series motors of large capacity ?

. Hopkinson’s test on D.C. machines is conducted at

. For which types of D.C. motor, dynamic braking is generally used ?

. Which method of braking is generally used in elevators ?

. In variable speed motor

. When the armature of a D.C. motor rotates, e.m.f. induced is

. Where D.C. motor of H.P. 12 or more requires frequent starting, stopping, reversing and speed control

. 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 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

. In the D.C. motor the iron losses occur in

. The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by