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

The correct answer is: A. Series motor

A series motor has got maximum self relieving property. This is because the armature current and field current are in series, so the torque is proportional to the square of the current. This means that if the load increases, the current will increase, which will increase the torque, which will help to overcome the load.

A shunt motor has a separate field winding, so the armature current and field current are not in series. This means that the torque is proportional to the armature current, not the square of the current. This means that if the load increases, the current will increase, but the torque will not increase as much as it would in a series motor.

A cumulatively compounded motor has both a series field winding and a shunt field winding. The series field winding is connected in series with the armature, and the shunt field winding is connected in parallel with the armature. This means that the torque is proportional to the sum of the armature current and the field current. This means that if the load increases, the current will increase, and the torque will increase more than it would in a shunt motor, but not as much as it would in a series motor.

A differentially compounded motor has both a series field winding and a shunt field winding. The series field winding is connected in series with the armature, and the shunt field winding is connected in parallel with the armature. However, the series field winding is connected in reverse polarity to the shunt field winding. This means that the torque is proportional to the difference between the armature current and the field current. This means that if the load increases, the current will increase, and the torque will decrease.

In conclusion, the series motor has got maximum self relieving property. This is because the armature current and field current are in series, so the torque is proportional to the square of the current. This means that if the load increases, the current will increase, which will increase the torque, which will help to overcome the load.