SOLUTION

Interpole windings are connected in series with the armature winding of a DC motor. This specific connection is crucial for improving commutation, a process that ensures smooth transfer of current from one commutator segment to the next.

Why Series Connection?

• Synchronizing Current: By connecting the interpole windings in series with the armature, the current flowing through them directly corresponds to the armature current. This ensures that the magnetic field produced by the interpoles is always synchronized with the armature current, leading to effective commutation.
• Counteracting Armature Reaction: Armature reaction is a phenomenon where the magnetic field produced by the armature current opposes the main field. Interpole windings, being in series, produce a magnetic field that counteracts this effect, improving commutation and reducing sparking at the brushes.
• Opposing polarity: Each interpole has a magnetic polarity opposite to the main pole ahead of it in the direction of rotation. As the armature current increases, the interpole field strength also increases, generating a magnetic field that opposes the distortion caused by the armature reaction.
• Neutralized main field: This opposing field partially cancels out the armature reaction, resulting in a more uniform main magnetic field.