If a DC generator was disassembled during overhaul, it is important that the brush holder rigging be installed in the neutral plane. On larger machines, if the brush rigging and end bells are not match-marked, what is the correct procedure for determining the neutral setting using factory marks?

Correct Answer: Option D — With the marked armature slots positioned directly under the center of the interpoles, the brushing rigging should be adjusted and clamped so that the brushes are positioned directly over the marked armature bars.

Aligning marked armature slots directly under the center of the interpoles places the brush rigging precisely in the neutral plane. This factory alignment ensures sparkless commutation across varying load conditions on large DC generators.