Question 272Electricity & Electronics - QMED

The correct answer is D) commutating pole windings. Commutating pole windings are used in DC generators to prevent the shifting of the neutral plane due to armature reaction for varying generator loads. The armature reaction can cause the neutral plane to shift, leading to excessive sparking at the brushes. The commutating pole windings create a compensating magnetic field that counteracts the armature reaction, keeping the neutral plane in the proper position and minimizing sparking at the brushes. The other options are incorrect because: A) brushing rigging does not directly prevent the shifting of the neutral plane, B) field pole windings do not compensate for armature reaction, and C) armature windings are responsible for the armature reaction that causes the neutral plane to shift.