Aboard ship or in a workshop, given access to 3-phase electrical AC motor and controller, a Megger test meter, and other proper tools and safety equipment.

Performance requirement

Behavior Standard
The student will: During assessment, the student shall, at a minimum:

Measure motor insulation resistance at motor controller

Use megger to perform insulation spot test:

  • de-energize motor, lockout/tagout if necessary
  • verify megger ground connection
  • connect lead to field winding
  • select appropriate test voltage
  • energize meter for 60 seconds, or until reading stabilizes at infinity
  • read meter

Correct insulation resistance measurement to standard temperature.

Correct reading to 40 °C using nomograph or correction chart.

Evaluate insulation resistance value

Compare corrected resistance to IEEE standard.

State whether resistance value is within acceptable limits


Assessed in EN‑4231 Sea Term IV: Marine Engineering.


  1. Table A-III/1 OICEW-B2.3
  2. NVIC 17-14 Task 7.3.A

See the Assessment Guidelines for additional specifications of behavior and standards.