scope:

This standard lists the required test procedures for qualification of modifications to an established electrical insulation system (EIS) with respect to its thermal classification. This international standard is applicable to EIS used in wire-wound electrotechnical devices with input voltage up to 1 000 V. The test procedures are comparative in that the performance of a candidate EIS is compared to that of a reference EIS, which has proven service experience in accordance with IEC 60791 or has been evaluated by one of the procedures given in IEC 61857 series.