This Guide applies to mineral oils, both uninhibited and inhibited against oxidation, in service, under normal operating conditions, in transformers, switchgear and similar electrical equipment where oil sampling is permissible. These oils are of the same type as those described in IEC Publication 296: Specincation for New Insulating Oils for Transformers and Switchgear.
Application of the recommendations of this document to oil in transformers of low power or voltage (< 1 MVA or < 36 kV) may require variation in the light of local economic circumstances (see preliminary remark No. 2 in Appendix Al).
SIS SS IEC 422:1986 history
1986SIS SS IEC 422:1986 Insulating oils - Malntenance and supervision guide for insulating oils in service