PD IEC TR 61857-2:2025

Electrical insulation systems. Procedures for thermal evaluation. Selection of the appropriate test method for evaluation and classification of electrical insulation systems | Status: Current

1 Scope This part of IEC 61857, which is a Technical Report, gives guidelines to identify the appropriate standard for the evaluation of a proposed electrical insulation system (EIS). Some of the standards evaluate the EIS using one stress factor which is thermal. Other standards evaluate the thermal stress factor with adjustments to the conditioning applied prior to the diagnostic testing to simulate applications in air. A third group of these standards when the application is other than in air. This document is applicable to existing or proposed EIS used in electrotechnical products across a wide range of operating voltages of IEC standards. This document identifies the appropriate standard based on construction and intended operating application.