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Replacing Motors, Part 8

Motor post-replacement insulation resistance tests

You probably agree it is overkill to perform several post-replacement insulation resistance tests on a small sump pump motor. But do you perform such testing for a motor that is expensive, operationally critical, or difficult to install? If not, why not?

A complete repair isn't just what you do to get things working again. If you replaced a 400-hp motor and the new one burned out six months later, can you really say your repair was complete?

Unfortunately, there's a trade-off between completeness and cost. The cost of a failed motor includes more than the cost of the replacement and the labor of installation. It could even include the inability to run any operations at all.

Your company can't afford the same level of care for each motor. Too much one way, and maintenance costs soar; too much the other way, and losses soar.

To get this right, follow this basic process:

  1. Starting with your critical processes, rate each motor for criticality on a scale of 1 to 10.
  2. Make a thorough list of post-replacement test procedures (include power quality tests, too), assigning these to the 10s.
  3. For each criticality grade below that, assign fewer procedures.

Review and adjust, based on actual failure data.



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