IEC 61858:2008

FOREWORD
INTRODUCTION
1 Scope
2 Normative references
3 Terms and definitions
4 General considerations
5 Evaluation of the change of thickness of an EIM
   5.1 Samples
   5.2 Acceptance
6 Substitution of winding wire
   6.1 General
   6.2 Substitution of enamel
   6.3 Substitution of conductor material
   6.4 Alternate winding wire
7 Substitution of impregnating resin/varnish
   7.1 Thermal class determination
   7.2 Evaluation
        7.2.1 Thermal classes equal or better
        7.2.2 One thermal class lower
        7.2.3 Other criteria
8 Substitution with other EIM
   8.1 Technically equivalent materials
   8.2 Previous evaluation
   8.3 Other
9 Evaluation of additions
   9.1 Addition of an impregnating resin/varnish
   9.2 Addition of other components
10 Single-point thermal ageing test
   10.1 Test objects
   10.2 Establishing the EIS relative thermal endurance
        index (EIS RTE)
   10.3 Interpretation of results
Annex A (normative) Classes of winding wire
Annex B (normative) Compatibility test procedure
Bibliography

IEC 61858:2008 lists the required test procedures for qualification of modifications of an established electrical insulation system (EIS) with respect to its thermal classification. This standard is applicable to EIS used in wire-wound electrotechnical devices. 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 60505 or has been evaluated by one of the procedures given in the IEC 61857 series.This third edition cancels and replaces the second edition, published in 2004 by IEC TC 98: Electrical insulation systems (EIS). It constitutes an editorial revision.