This part of IEC 61857 specifies a general test procedure for the thermal evaluation and
qualification of electrical insulation systems (ELS) and establishes a procedure that compares
the performance of a candidate ElS to that of a reference ElS.
This standard is applicable to existing or proposed ElS used in electrotechnical products with
an input voltage of up to 1 000 V where the thermal factor is the dominating ageing factor.