During PM inspection, what is the purpose of verifying insulation resistance?

• A. To verify mounting alignment.
• B. To verify insulation resistance and detect leakage paths.
• C. To check fluid levels.
• D. To measure vibration.

Answer: (B)

Verifying insulation resistance during PM testing checks how well electrical insulation prevents current from leaking between conductors and to ground. A high insulation resistance means the insulation is intact and effective; a low reading points to leakage paths created by moisture, dirt, damaged insulation, or degraded connections. Identifying these leakage paths helps prevent electrical faults such as shorts, overheating, arcing, or shocks, contributing to safer and more reliable equipment operation. The other options describe mechanical checks (mounting alignment, fluid levels, vibration) that aren’t related to how well insulation blocks electrical leakage.