This is a standard test procedure for the thermal evaluation and qualification of electrical insulation systems (EISs) for random-wound ac electric machinery@ where thermal degradation is the dominating aging factor. This procedure compares the relative thermal performance of a candidate EIS to that of a reference EIS. This standard covers insulation systems for such machinery with operating voltage of up to 600 V at 50/60 Hz. This standard provides a statistical method for establishing a relative life-temperature relationship for an insulation system. To have any significance@ the reference insulation system must be supported with adequate field-service data. This procedure is intended to evaluate insulation systems for use in air-cooled@ random-wound ac electric machinery with ??usual service conditions.?? This procedure@ on its own@ does not cover insulation systems such as exposure to conducting contaminates@ radiation@ inverter applications@ or operation in oils@ refrigerants@ or other media that potentially degrade insulating materials Purpose The purpose of this standard procedure is to classify insulation systems in accordance with their temperature limits by test@ rather than by chemical composition. This test procedure has been prepared to outline useful methods for the evaluation of systems of insulation for random-wound stators of rotating electric machines. The motorette procedure described is used for the evaluation of EISs.