EVS-EN IEC 63585:2026

This document gives guidelines to the transformer operator in evaluating dissolved gas analysis (DGA) data obtained from natural ester according to IEC 62770 [31] and synthetic ester according to IEC 61099 [29] in liquid filled transformers and similar equipment. Due to limited information on equipment filled with mono- and blended esters (IEC 63012 [33]) at present they are included in Annex D.
Ester liquids are present in the whole range of applications including transport and distribution networks, industrial, traction, wind and solar transformers as reflected in the tables related to the data gathered in this document. Nowadays their use has been extended to power transformers. Ester liquids are also increasingly used in combination with tap-changers. Due to insufficient DGA data available, switching equipment is excluded from this document.
This document includes the following:
– gas generation in a natural or synthetic ester-filled transformer;
– gas concentration guide values valid for the use of DGA interpretation tools;
– methods for the interpretation of the dissolved gas results; – recommended actions based on the interpretation of dissolved gas analysis results;
– examples of faulty equipment.