Liquid solvent ________ ___ be applied to a commutator.

• A. should not
• B. should
• C. can
• D. must

Answer: (A)

Cleaning a commutator with liquids is avoided because the surface is closely coupled to windings and insulation. Liquid solvents can wick into the armature, wash away protective lubricants, and leave residues that attract dust. They can also soften or damage the mica insulation between the copper bars, create conductive paths, and promote corrosion or arcing as the commutator turns. For these reasons, a liquid solvent should not be applied to a commutator. Dry cleaning methods—such as brushing or wiping with a clean, dry cloth—are preferred, and if any solvent is used, it should not be applied directly to the commutator and the area must be thoroughly dried before operation.