Thermal Endurance of Silicone Magnet Wire Evaluated by Motor Test [includes discussion]

In October 1952 a motor test program was started at Dow Corning Corporation to evaluate a series of new modified silicone magnet-wire enamels. The purpose of this program is to determine by functional test methods the thermal life of these new enamels. Twelve 7½-horsepower induction motors insulated with silicone components and wound with wire enameled with Dow Corning 1360 wire enamel have been tested. In addition, five similar motors insulated with class-A materials have been tested to obtain data indicating the relative life-temperature characteristics of the class-A system for comparison with the silicone system. The data indicate that motors insulated with silicone components and wound with wire enameled with Dow Corning magnet-wire enamel can be operated at an average copper temperature in the range of 160 to 180 C with a life comparable to class-A insulated motors operated within their temperature limits.