prEN IEC 63585:2025

Interpretation of Dissolved Gas Analysis in natural and synthetic esters

Interprétation de l'analyse des gaz dissous dans les esters naturels et synthétiques

Tolmačenje analize raztopljenih plinov v naravnih in sintetičnih estrih

General Information

• Status: Not Published
• Publication Date: 09-Nov-2026
• Technical Committee: CLC/SR 10 - Fluids for electrotechnical applications
• Current Stage: 4060 - Enquiry results established and sent to TC, SR, BTTF - Enquiry
• Start Date: 11-Jul-2025
• Completion Date: 11-Jul-2025
• Ref Project: oSIST prEN IEC 63585:2025 - Interpretation of Dissolved Gas Analysis in natural and synthetic esters

Standards Content (Sample)

SLOVENSKI STANDARD
01-junij-2025
Tolmačenje analize raztopljenih plinov v naravnih in sintetičnih estrih
Interpretation of Dissolved Gas Analysis in natural and synthetic esters
Interprétation de l'analyse des gaz dissous dans les esters naturels et synthétiques
Ta slovenski standard je istoveten z: prEN IEC 63585:2025
ICS:
29.040.20 Izolacijski plini Insulating gases
71.080.70 Estri Esters
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

10/1261/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 63585 ED1
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2025-04-18 2025-07-11
SUPERSEDES DOCUMENTS:
10/1246/CD, 10/1260/CC
IEC TC 10 : FLUIDS FOR ELECTROTECHNICAL APPLICATIONS
SECRETARIAT: SECRETARY:
Italy Mr Riccardo Maina
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):
TC 14,SC 36A,TC 38,TC 112
ASPECTS CONCERNED:
Electricity transmission and distribution
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CENELEC, is drawn to the fact that this Committee Draft for
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This document is still under study and subject to change. It should not be used for reference purposes.
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clauses to be included should this proposal proceed. Recipients are reminded that the CDV stage is the final stage for
submitting ISC clauses. (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Interpretation of Dissolved Gas Analysis in natural and synthetic esters

PROPOSED STABILITY DATE: 2028
NOTE FROM TC/SC OFFICERS:
this electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee
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CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions and abbreviations . 9
3.1 Terms and definitions. 9
3.1.1 Insulating liquids considered in this document . 9
3.1.2 Fault . 9
3.1.3 Failure . 9
3.1.4 Electrical fault . 9
3.1.5 Partial discharge . 9
3.1.6 Disruptive discharge . 10
3.1.7 Thermal fault . 10
3.1.8 90 or 95 percentiles of gas concentrations and gassing rates . 10
3.2 Abbreviations . 11
3.2.1 Chemical names and formulae . 11
3.2.2 Most common abbreviations . 11
4 Gas generation in a natural and synthetic ester-filled transformer . 11
4.1.1 Physical and Chemical properties . 12
4.1.2 Gassing behaviour under dielectric breakdown and thermal stress . 12
4.1.3 Stray Gassing under thermo-oxidative stress . 14
5 Interpretation schemes . 16
5.1 90 or 95 Percentiles of gas concentrations . 17
5.2 Gas ratios . 18
5.2.1 Two-gas ratios for partial discharge (PD) in synthetic and natural esters . 19
5.2.2 Two-gas ratios for discharge (D) in synthetic and natural esters . 19
5.2.3 Two-gas ratios for thermal fault (T) in synthetic esters . 19
5.2.4 Two-gas ratios for thermal fault (T) in natural esters . 19
5.2.5 General considerations for two-gas ratios . 19
5.3 Gas increase rates . 20
5.4 Trend analysis . 20
5.5 Graphical representation . 21
6 Dissolved Gas Analysis during factory acceptance tests (FAT) . 21
7 Database interpretation . 21
7.1 Uncertainties in the database interpretation . 22
7.2 Restrictions of database interpretation . 22
8 DGA accuracy . 22
9 DGA verifications . 22
10 Recommended actions based on the interpretation of dissolved gas analysis
results . 22
11 Examples of faulty equipment and trend analysis . 23
Annex A Solubility of gases in mineral oils . 24
(informative) . 24
Annex B Interpretation schemes used with mineral oils (informative) . 25

IEC CDV 63585 ED1 © IEC 2025 - 3 -
Annex C Additional types of faults detectable with the interpretation schemes of
Duval’s Pentagons 3 and Triangles 3 for identifying the further faults  in ester
liquids, by analogy with Duval Pentagons 1-2 [16, 17, 18] (informative) . 27
Annex D Results of Database Evaluation (informative) D.1 Database on natural esters
(µl/l) . 29
D.2 Database on synthetic esters (µl/l) . 30
Annex E Examples of failure cases and trend analysis . 31
(informative) . 31
E.1 Corona Partial Discharge (PD) Example . 31
E.1.1 Transformer data . 31
E.1.2 DGA Results (in µl/l) . 31
E1.3 Interpretation Scheme . 31
E1.4 Graphic Representations . 32
E1.5 Transformer Inspection . 33
E.2 Discharge (D) Example . 33
E.2.1 Transformer data . 33
E.2.2 DGA Results (in µl/l) . 33
E.2.3 Interpretation Scheme . 34
E.2.4 Graphic Representations . 34
E.2.5 Transformer Inspection . 35
E.3 Thermal (T) Example . 36
E.3.1 Transformer data . 36
E.3.2 DGA Results (in µl/l) . 36
E.3.3 Interpretation Scheme . 36
E.3.4 Graphic Representations . 37
E.3.5 Transformer Inspection . 37
E.4 Trend development Example 1 . 38
E.4.1 Transformer data . 38
E.4.2 DGA Results (in µl/l) . 38
E.4.3 Interpretation Scheme: . 39
E.4.4 Graphical trend representation . 40
E.4.5 Graphic Representations with the Duval pentagon . 40
E.4.6 Transformer Inspection . 40
E.5 Trend development Example 2 . 41
E.5.1 Transformer data . 41
E.5.2 DGA Results (in µl/l) . 41
E.5.3 Interpretation Scheme . 41
E.5.4 Graphical trend representation . 42
E.5.5 Graphic Representations with the Duval pentagon . 43
E.5.6 Transformer Inspection . 43
Annex F Available information on dissolved gas analysis of mono- and blended esters . 44
(informative) . 44
F.1 Palm fatty acid ester (PFAE) . 44
F.2 Blended esters according to IEC 63012 . 44
Bibliography . 45

Figure 1. Relative gas generation after 100 breakdowns in accordance with IEC 60156
(5s pause between breakdowns without stirring). . 13

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Figure 2. Gas generation after ageing at 120°C for 64h on air saturated insulated
liquids . 14
Figure 3a – c. Hydrogen evolvement because of stray gassing of synthetic ester (3a),
natural ester on soybean basis (3b) and uninhibited mineral oil (3c) at 105°C for 48h
under different conditions: air – air saturated, air+Cu air saturated in the presence of
copper, N2 – nitrogen saturated, N2+Cu – nitrogen saturated in the presence of copper . 15
Figure 4a - c. Methane evolvement because of stray gassing of synthetic ester (4a),
natural ester on soybean basis (4b) and uninhibited mineral oil (4c) at 105°C for 48h
under different conditions: air – air saturated, air+Cu air saturated in the presence of
copper, N2 – nitrogen saturated, N2+Cu – nitrogen saturated in the presence of copper . 15
Figure 5a - c. Ethane evolvement because of stray gassing of synthetic ester (5a),
natural ester on soybean basis (5b) and uninhibited mineral oil (5c) at 105°C for 48h
under different conditions: air – air saturated, air+Cu air satura
...