## Electrical Machines The DC compound motors are generally

None of these.
Level Compound.
Differentical compound.
Cummulative compound.

## Electrical Machines In case of a dc motor the ratio Eb / E is indicative of

efficiency.
ratio of starting to running current.
ratio of starting to running torque.
ratio of input to output voltage.

## Electrical Machines Which of the following represents the rotating losses of machine?

Eddy current losses
All of the them
Hysteresis losses
Friction and windage losses

## Electrical Machines The use of double squirrel cage winding on the rotor provides

low noise.
reduced starting torque.
higher efficiency.
a large starting torque.

(1/2)Fmax.
3Fmax.
Fmax.
(3/2)Fmax.

## Electrical Machines Consider the following statements about commutating poles which are fitted on most large dc Shunt motors: 1. The commutating poles are placed in the geometric neutral plane and their number is usually Equal to the number of main poles 2. The winding on the commutating poles is connected in series with the shunt-field winding on the main poles 3. The polarity of the commutating pole must be that of the next pole further ahead 4. The commutating poles neutralize the reactance voltage produced in the coil undergoing Commutation. Of these statements,

1, 2 and 3 are correct
2, 3 and 4 are correct
1 and 4 are correct
1, 2 and 4 are correct