You direct the electrician to take quarterly insulation resistance reading of the ship's critical motors. What additional directions would you give to ensure accurate readings are taken that will allow for the logical comparison of prior and current readings?
• Insulation resistance changes with temperature and moisture conditions • For trending equipment condition, the test conditions must be as consistent as possible each time • Hand‑crank megohmmeters require a specified test duration at rated voltage to be comparable
• Which factor will most affect your ability to compare today’s readings with readings taken months ago under different conditions? • If you want to know whether the insulation is actually getting better or worse, what do you need to keep the same or mathematically compensate for? • Think about what manufacturers usually specify when giving minimum acceptable insulation resistance values—what condition do they assume?
• Verify which option talks about normalizing the measurement so that different test days can be compared fairly • Check which choice addresses a known physical influence on insulation resistance values, rather than just a test procedure detail • Confirm that the selected option would still allow logical comparison even if tests are done in different ambient conditions (e.g., summer vs. winter)
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