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This is a standard test procedure for the thermal evaluation and qualification of electrical insulation systems for Random-Wound AC Electric Machinery, where thermal degradation is the dominating aging factor. This procedure compares the relative thermal performance of a candidate Electrical Insulation System (EIS) to that of a reference Electrical Insulation System. This standard covers insulation systems for such machinery with input voltage of up to 1000 Volts at 50/60 Hertz. 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.