Premature Arc Fault Breaker Failures

Electrical engineering root cause analysis (RCA) related to premature arc fault breaker failures and their solutions.

Article Type:Root Cause Analysis (RCA)
Equipment Type:Motors
Author:S. Raghava Chari

Note: This root cause analysis (RCA) is from real-time scenarios that happened in industries during the tenure of two or three decades ago. These articles will help you to improve your troubleshooting skills and knowledge.

Arc Fault Breaker Failures Problem

3.3. KV motors antifriction bearings did not last 6-months even!

Author Root Cause Analysis

Peculiar pits at the inner race and outer race rolling-element contacting area pointed out induced current circulation via the Arc Fault Breaker (AFBs) as RC.


The author declined the manufacturer’s offer of free replacement Arc Fault Breaker (AFBs); he pointed out a German Motor fitted with an insulating sheet below the Plummer block to stop shaft current circulation and insisted on a similar solution.

Finally, the manufacture fitted a Nylon insert at the NDE bearing seat of each motor.

Shaft current circulation ceased and hence AFB’s suffered no shaft current flow failures.

Author: S. Raghava Chari

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