Interaction of varnish with magnet wire enamel

Some varnishes can interact with magnet wire enamels and reduce the thermal life rating of the insulation system below that of the enamel itself. This interaction in some cases is called incompatibility. In essence it is a reduction in the reliability of electrical insulation in rotating machinery, and with this the reliability of the machinery itself. Clarification of the mechanism of this interaction should lead to the wiser selection of enamels and varnishes for rotating electrical equipment with increased reliability and yielding the increased economies associated with improved reliability of machinery.