What is meant by armature reaction? Explain how compensating winding and interpoles are used tominimize the effect of armature reaction.

Armature reaction refers to the effect on the magnetic field in the motor due to the magnetic field created by the armature current. In a DC motor, when current flows through the armature winding, it produces its own magnetic field. This magnetic field distorts the main magnetic field and affects the performance of the motor. This effect is known as armature reaction.

To minimize the effect of armature reaction, compensating windings and interpoles are used:

1. Compensating Windings: These are series windings embedded in the main pole of the motor. They carry the same current as the armature and produce a magnetic field that opposes the magnetic field of the armature. This helps to neutralize the effect of the armature magnetic field and reduces the distortion of the main magnetic field.

2. Interpoles: These are small poles placed between the main poles and are connected in series with the armature. The magnetic field produced by the interpoles is in the opposite direction to the magnetic field of the armature. This helps to neutralize the effect of the armature reaction at the commutation zone, reducing sparking and improving the performance of the motor.

In summary, both compensating windings and interpoles are used to counteract the effect of the armature reaction, improving the efficiency and performance of the motor.