This test code has been prepared in the hope that it will serve as a useful guide for the evaluation of insulation systems for random wound rotating electric machines, and to establish a sound basis for their temperature classification. Once this is accomplished in orderly and organized fashion, the problems of insulation selection for use in electric apparatus should be simplified. The code defines test procedures. It does not establish any normal values for insulation life, nor does it provide any standards of performance whatever.

The chief purpose of this test code is to classify insulation systems in accordance with their temperature limits by test, rather than by chemical composition. The intention is, first, to classify according to the recognized A, B, and H categories, whose usual continuous hot-spot temperatures are 105, 130, and 180C, respectively. Second, to ascertain whether it is appropriate to change the present hot-spot temperatures for certain applications. It is not the intention at present to use this code to define any new or intermediate insulation temperature glasses. This section suggests appropriate samples of insulating materials or insulating systems, which may be usefully subjected to the exposures outlined in Section 2, to simulate their behavior in service. It is considered that one insulation specimen, as defined in the following, will adequately represent all fractional horsepower motors component; and, conversely, compatibility or other problems may arise whereby the highest temperature component is rendered unsuitable for use at its classified temperature.