Answer by Hugh Falkner
Few intensively used industrial motors will go through their working life without needing some attention from a motor repairer. Having established that repair is preferable to complete replacement, how do you identify a quality repairer?
Hazardous area motors can only be repaired by companies with the correct accreditation, but for standard motors there is no general certification scheme to identify a quality repairer. In the absence of personal recommendations, the following questions should be asked:
- Qualifications and experience of their staff. Does it seem sufficient?
- Do they have a wide range of wire gauges? It should be adequate to avoid having to make inefficient substitutes.
- How often do they calibrate the burn out oven thermostat? If the temperature is not well controlled, then the laminations are more likely to be damaged while removing the wire.
- As far as is possible, does the workshop look reasonably clean and tidy? Quality repair is about attention to detail, and so a workmanlike environment really does matter.
- What are their procedures for inspecting a motor on arrival, and on departure?
- Do their main customers seem to be those that will value quality?
Some repairers will be accredited to a Quality Standard, but this will only warrant that they are following declared procedures. It will not be a guarantee that these are the optimal ones for motor repair.
For information on best practice repair of motors, the following guide is recommended: The effect of repair/rewinding on motor efficiency (EASA). This is available free for download at http://www.easa.com/MaintainingMotorEfficiency.
It shouldn’t be forgotten that the motor user also has a responsibility in ensuring a quality repair, as demanding a high speed repair, or the repair of a motor that should really be scrapped, will lead to an inevitable compromise in quality.
If you are wondering whether a motor should be replaced or repaired, see also our application note on Electric motor asset management.
Last update 2-Jul-2021