The evaluation of enamel magnet wire

This paper is a discussion of the need to broaden the base of test procedures relating to enameled magnet wires. At present, the AIEE Publication no. 57, revised in 1959, establishes a method for determining the relative life of enameled wires as a function of thermal stability.1 Also available to air evaluation are the AIEE test procedures 65, 510, and 511.2 These are intended for evaluation of systems of which magnet wire insulations are an integral part. Experience is showing the desirability of providing acceptable test procedures for determining the relative life and the practicability or suitability of magnet wires as functions of other characteristics. Of importance, in this respect, are: 1. compatibility of the wire enamels with other substances, both of insulating function and environmental in nature, which are present in a complete electrical system, 2. thermoplastic flow properties, 3. heat shock characteristics, 4. change of reaction rate of aging properties with increase in temperature, 5. heat softening after extended aging, 6. retention of flexibility after aging, and 7. winding problems reflected in abrasion resistance, flexibility, reaction to rapid elongation, etc.