Fundamentals-a useful index for estimating residual life of motor insulation

During the period from 1955 to 1978, the insulation system of choice for motor windings in Japan was predominantly of the polyester type. Since there are still a number of polyester-insulated motors in the field, there is a demand for a reliable means of evaluating the residual life of these units, the ultimate goal being standardization acceptable to the industry. The present state of this effort in Japan is briefly reviewed. A simple but effective procedure for the diagnostic evaluation of motor life is offered. It is based on tests easily performed on the insulation and within the scope of the average motor repair shop facilities.<
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