Rewinding and Reusing Fire-Damaged Motors

Jacojan,

Sorry to hear about your fire loss. I hope your factory can recover. Modern motor shops use temperature-controlled burn-out ovens to remove the varnish from the windings so they can be stripped out in order to do a rewind of the motor. This temperature control is critical to maintaining the magnetic properties of the steel, as another person has said. Depending on the size of the motors and the duration of the fire, it is quite possible that the motor temperatures may not have exceeded the safe temperature for a successful rewind.

I suggest that you take a representative motor to a reputable rewind shop (I have no idea where you are) so I can't suggest how to locate one near you. In the USA the good shops are almost always members of EASA, their trade association. After the rewind, they can put the motor on a dynamometer and check its performance at full load, to see if it has any problems from localized heating or lowered efficiency. Choose a shop that can give you certified results.

If the shop personnel tell you to replace the motor(s), their reasons should be listened to. The last time I worked in a rewind shop, buying a new motor was almost always recommended for smaller ones (less than 10-Hp), unless they were of an unusual design. For larger ones, rewinds are usually cost-effective, and sometimes are also quicker than buying new motors.

Regards--JMM

As indicated elsewhere, not knowing where you are located, extent of insurance coverage, etc, one is limited in offering a *best* course of action. However; from my own, personal EASA shop rewinding days : IF the cores are still usable [[and there is a test that is easily run, using test loops of welding-lead cable through the stripped-out core to check for "hot-spots"]] then a rewind can be even better than a factory winding job.

The size of the motors (as well as availability of direct replacements) usually guides the decision making process. Rewinds used to be priced at around 3/4 the cost of new... and, if the slot insulation and wire class are being upgraded from factory, you would be well advised to rewind (again, assuming the cores are salvageable).

A reputable shop should offer to do the testing for a small fee (saving and selling your old copper as well), and sell you only what you need ; i.e., "Rewind THESE, and let's replace these others..."

Best Wishes ~