Bar Edge Burning is a fault in a commutator. Which of the following describes a related condition?

• A. High mica
• B. One burnt segment
• C. Interpole strength mismatch
• D. Bearing wear

Answer: (B)

Bar edge burning shows up as arcing at the edge of a commutator bar, which charps the copper at that edge. The most fitting related condition is a single burnt segment, because the arc tends to affect just the specific bar where the edge burns, leaving that segment visibly burned or discolored. This direct, localized damage is the immediate physical sign you’d look for after bar edge burning. Other issues don’t fit as neatly: high mica involves insulation between bars rather than a localized burn on a segment; an interpole strength mismatch can cause sparking but isn’t described by a burnt segment; bearing wear is a mechanical problem unrelated to the commutator surface condition.