Functional Evaluation of Motor Insulation Systems [includes discussion]

The present paper proposes a method for the functional evaluation of insulation systems associated with random wound induction motors in the approximate range of 1 to 40 horsepower or with equipment using a similar insulation system. With this method, a measure of the performance of any motor insulation system can be ascertained for comparison with that of an acceptable standard and any new system may thereby be classified. A specific form of sample, or model motor, is described and a test cycle of repeated periods of exposure to heat, vibration, moisture, and voltage is proposed. By comparing the life of insulation systems, when exposed to repeated test cycles of this kind, with the life of complete motors under various accelerated and service conditions, it is believed that it will be possible to evaluate new insulating materials more quickly and accurately than heretofore possible.