The interpoles in dc machines have a tapering shape in order to
A. reduce the overall weight
B. reduce the saturation in the interpole
C. economise on the material required for interpoles and their windings
D. increase the acceleration of commutation
Answer: B
Share your understanding of this question with the correct explanation.
The correct answer is B. The interpoles in DC machines have a tapering shape in order to reduce the saturation in the interpole.
Interpoles, also known as commutating poles, are small auxiliary poles placed between the main field poles of a DC machine. They are designed to improve the commutation process by reducing the sparking at the brushes.
When the armature coils pass under the main field poles, they induce an opposing voltage, known as the armature reaction, which can cause improper commutation and sparking at the brushes. The interpoles are connected in series with the armature circuit and produce a flux that opposes the armature reaction, aiding in commutation.
By tapering the shape of the interpoles, the magnetic field distribution is more uniform along the interpolar gap. This helps to reduce the saturation in the interpole region, ensuring that the interpole flux is effective in compensating for the armature reaction and improving commutation.
Therefore, the tapering shape of the interpoles is specifically designed to reduce the saturation in the interpole and improve the commutation process in the DC machine.