Question 6A332

In a DC motor, as the armature coils rotate and pass under the brushes, the current flowing through them must reverse direction. This rapid change in current, due to the coil's inductance, induces a reactive voltage that can cause significant sparking at the brushes, leading to wear and inefficiency. To counteract this, auxiliary poles are introduced between the main field poles. These auxiliary poles are designed to generate a localized magnetic field that induces an opposing voltage in the armature coils undergoing commutation. This counter-voltage effectively neutralizes the reactive voltage, allowing for "sparkless commutation" without needing to physically shift the brushes. These auxiliary poles are commonly referred to as **interpoles** or **commutating poles**. Since both terms describe the same component and its function in reducing brush sparking, "Either A or B" is the correct answer.