Some Relations of Thermal Cycling to Thermal Life Temperature Classification of Enameled Wire Determined by AIEE 57 Test Procedures

The industry has long recognized that thermal cycling and thermal shock resistances of enameled wire play an important part in determing the thermal life by AIEE 57 test methods. Data are presented for varying thermal cycling indicating significant arivariation of temperature classification roughly from Class 155°C to Class 105°C for the same wire enamel. It is also shown that if the thermal cycling procedure is held constant, reasonable conformity of test results can be expected.