oSIST prEN IEC 60422:2023
(Main)Mineral insulating oils in electrical equipment - Supervision and maintenance guidance
Mineral insulating oils in electrical equipment - Supervision and maintenance guidance
Isolieröle auf Mineralölbasis in elektrischen Betriebsmitteln - Leitlinie zur Überwachung und Wartung
Huiles minérales isolantes dans les matériels électriques - Lignes directrices pour la maintenance et la surveillance
Mineralna izolacijska olja v električni opremi - Napotki za nadzorovanje in vzdrževanje
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
oSIST prEN IEC 60422:2023
01-junij-2023
Mineralna izolacijska olja v električni opremi - Napotki za nadzorovanje in
vzdrževanje
Mineral insulating oils in electrical equipment - Supervision and maintenance guidance
Isolieröle auf Mineralölbasis in elektrischen Betriebsmitteln - Leitlinie zur Überwachung
und Wartung
Huiles minérales isolantes dans les matériels électriques - Lignes directrices pour la
maintenance et la surveillance
Ta slovenski standard je istoveten z: prEN IEC 60422:2023
ICS:
29.040.10 Izolacijska olja Insulating oils
oSIST prEN IEC 60422:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN IEC 60422:2023
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oSIST prEN IEC 60422:2023
10/1194/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60422 ED5
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2023-04-07 2023-06-30
SUPERSEDES DOCUMENTS:
10/1165/CD, 10/1183A/CC
IEC TC 10 : FLUIDS FOR ELECTROTECHNICAL APPLICATIONS
SECRETARIAT: SECRETARY:
Italy Mr Massimo Pompili
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
TC 14, SC 17A, TC 20, SC 36A, TC 38, TC 99, TC 112
Other TC/SCs are requested to indicate their interest, if any, in
this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for Vote
(CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of
• any relevant patent rights of which they are aware and to provide supporting documentation,
• any relevant “in some countries” clauses to be included should this proposal proceed. Recipients are reminded that the
enquiry stage is the final stage for submitting "in some countries" clauses. See AC/22/2007.
TITLE:
Mineral insulating oils in electrical equipment – Supervision and maintenance guidance
PROPOSED STABILITY DATE: 2026
NOTE FROM TC/SC OFFICERS:
Copyright © 2023 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this
electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.
You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without
permission in writing from IEC.
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CONTENTS
Scope . 9
1
2 Normative references . 9
3 Terms and definitions . 11
4 Properties and deterioration/degradation of oil . 12
5 Categories of equipment . 12
6 Sampling of oil from equipment . 13
7 In-service oil diagnostic tests. 14
General . 14
Colour . 15
Appearance . 15
Breakdown voltage (BDV). 15
Water content . 16
Water content in the oil/paper-system . 16
Influence of water on the solid/liquid dielectric system . 16
Water in oil . 17
Water in the solid insulation . 18
Interpretation of results. 19
Acidity . 20
Dielectric dissipation factor (DDF) and resistivity . 21
Inhibitor content . 22
Oxidation stability . 22
Monitoring of uninhibited and inhibited oils . 22
Sediment . 22
Sludge . 23
Interfacial tension (IFT) . 23
Particles . 23
Flash point . 24
Compatibility . 24
Compatibility between different insulating mineral oils (miscibility) . 24
Pour point . 25
Density . 25
Viscosity. 26
Polychlorinated biphenyls (PCBs) . 26
Corrosive sulphur in mineral insulating oil . 26
Corrosive sulphur . 27
Potentially corrosive sulphur . 27
Dibenzyl disulphide (DBDS) . 27
Metal Passivator . 27
Air Release and Foaming . 28
8 Evaluation of mineral insulating oil in new equipment . 28
9 Evaluation of oil in service . 29
General . 29
Frequency of examination of oils in service . 30
Testing procedures . 31
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IEC CDV 60422 IEC 2023 – 3 –
General . 31
Field tests. 31
Laboratory tests . 32
Classification of the condition of oils in service . 32
Transformers . 32
Tap-changers . 32
Instrument and protection transformers . 33
Circuit breakers and switchgear . 33
Oil filled and OIP bushings . 33
Corrective action . 33
10 Interpretation of results . 35
11 Handling and storage . 46
12 Replacement of oil in electrical equipment . 47
Replacement of oil in transformers with an U below 72,5 kV and in
m
switchgear and associated equipment . 47
Replacement of oil in transformers with an U of 72,5 kV and above . 47
m
Replacement of oil in electrical equipment contaminated with PCBs . 48
13 Addition of metal passivators to in-service oil . 48
14 Treatment . 48
WARNING . 48
Classification of Treatment Processes . 49
Off-Line (de-energized) vs On-Line (energized) treatment . 49
Batch vs Continuous Mode Treatment . 50
Reconditioning (degassing, drying and filtration) . 50
General . 50
Reconditioning equipment . 51
Application to electrical equipment . 53
Reclaiming . 54
General . 54
Reclaiming by percolation with single use sorbents . 54
Reclaiming process using reactivating sorbents . 55
Renewal of additives . 56
Removal of PCBs using dehalogenation and related processes . 57
General . 57
Dehalogenation processes using sodium and lithium derivatives . 57
Dehalogenation processes using polyethylene glycol and potassium
hydroxide (KPEG) . 57
Dehalogenation in continuous mode by closed circuit process . 57
Corrosive sulphur removal using KPEG . 57
Criteria for oil reclamation and treatments . 58
Annex A (normative) Criteria for reclamation and treatments . 59
A.1 Introduction . 59
A.2 Key parameters to measure before and after reclamation . 59
A.3 Addition of inhibitor after reclamation . 60
A.4 Time and location of sampling . 60
Annex B (informative) General guideline for moisture %RS for continuous online
monitoring . 62
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Annex C (informative) Normalizing water in oil for comparison and trending (Historical
practice) . 63
C.1 General . 63
C.2 Sampling temperature at or above 35 °C . 63
Annex D (informative) Material Compatibility . 65
Annex E (informative) Test method for determination of sediment and sludge . 67
E.1 Sediment determination . 67
E.2 Sludge determination . 67
Annex F (informative) Contamination of oils with silicone . 68
Annex G Bibliography . 69
LIST OF FIGURES
Figure 1 – Water solubility curves for unused mineral oil as adapted from literature [3]
(According to Equation (3)) . 18
Figure 2 – Hysteresis loops of %RS vs. oil temperature in transformers with 3 different
water content levels [3] . 20
Figure 3 – Correlation between resistivity and dissipation factor [4] . 21
Figure 4 – Normalization factors according to Equation (6) . 64
LIST OF TABLES
Table 1 – Categories of equipment . 13
Table 2 – Tests for in-service mineral insulating oils . 14
Table 3 – Recommended limits for mineral insulating oils after filling in new electrical
equipment prior to first energization at site . 29
a
Table 4 – Recommended frequency of testing . 31
Table 5a – Transformers and Reactors – Application and interpretation of tests (1 of 6) . 35
Table 6 – Summary of typical actions . 46
Table 7 – Conditions for processing mineral insulating oils (both inhibited and
uninhibited) . 51
Table 8 – Beta ratio related to filter efficiency . 52
Table 9 – Parameters where limits should be agreed upon . 59
Table 10 – Parameters where limits should not necessarily be set but should be
measured for baseline and trending . 60
Table 11 – Moisture %RS, continuous online monitoring, general guideline . 62
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IEC CDV 60422 IEC 2023 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MINERAL INSULATING OILS –
GUIDELINES FOR MAINTENANCE AND USE IN ELECTRICAL EQUIPMENT
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60422 has been prepared by IEC technical committee 10: Fluids for
electrotechnical applications.
This fifth edition cancels and replaces the fourth edition, published in 2013, and constitutes a
technical revision.
The main changes with respect to the previous edition are as follows:
This new edition represents a major revision of the fourth edition, bringing this standard in line
with the latest developments in oil condition monitoring. New interpretation tables have been
created, containing limits for oil parameters specific to plant type with suggested corrective
actions in the tables and new test methods.
The action limits for all oil tests have been revised and changes made where necessary to
enable users to use current methodology and comply with requirements and regulations
affecting safety and environmental aspects.
Category O has been removed and is now incorporated within category A.
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In addition, this standard incorporates changes introduced in associated standards since the
fourth edition was published.
The text of this standard is based on the following documents:
FDIS Report on voting
10/XXXX/FDIS 10/XXXX/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until the
stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to
the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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oSIST prEN IEC 60422:2023
IEC CDV 60422 IEC 2023 – 7 –
1 INTRODUCTION
2 Insulating mineral oils are used in electrical equipment employed in the generation,
3 transmission, distribution and use of electrical energy.
4 Monitoring and maintaining oil quality is essential to ensure the reliable operation of oil-filled
5 electrical equipment. Codes of practice for this purpose have been established by electrical
6 power authorities, power companies and industries in many countries.
7 A review of current experience reveals a wide variation of procedures and guidance. It is
8 possible, however, to compare the value and significance of standardized oil tests and to
9 recommend uniform criteria for the evaluation of test data.
10 If a certain amount of oil deterioration (by degradation or contamination) is exceeded, there is
11 inevitably some erosion of safety margins and the question of the risk of failure should be
12 considered. While the quantification of the risk can be very difficult, a first step involves the
13 identification of potential effects of increased deterioration. The philosophy underlying this
14 standard is to furnish users with as broad a base of understanding of oil quality deterioration
15 as is available, so that they can make informed decisions on inspection and maintenance
16 practices.
17 Mineral oils are valuable resources and should be utilised accordingly. Used mineral oils are,
18 by most regulations, deemed to be controlled waste. If spills occur, this may have a negative
19 environmental impact especially if the oil is contaminated by persistent organic pollutants such
20 as polychlorinated biphenyls (PCBs).
21 This International Standard, whilst technically sound, is mainly intended to serve as a common
22 basis for the preparation of more specific and complete codes of practice by users in the light
23 of local circumstances. Sound engineering judgement will have to be exerted in seeking the
24 best compromise between technical requirements and economic factors.
25 Reference should also be made to instructions from the equipment manufacturer.
26 General caution
27 This standard does not purport to address all the safety problems associated with its use. It is
28 the responsibility of the user of this document to establish appropriate health and safety
29 practices and determine the applicability of regulatory limitations prior to use.
30
31 The mineral oils which are the subject of this document shall be handled in compliance with
32 local regulations and supplier’s safety datasheets.
33 Environment, Health & Safety
34 This standard is applicable to mineral oils, chemicals and used sample containers. The disposal
35 of these items should be carried out according to local regulations regarding their impact on the
36 environment.
37 Attention is drawn to the fact that, at the time of writing this standard, some mineral oils in
38 service are known to be contaminated to some degree with other liquids, for example, silicone
39 oils and PCBs.
40 Because of this, safety countermeasures should be taken to avoid risks to workers, the public
41 and the environment during the life of the equipment, by strictly controlling spills and emissions.
42 Disposal or decontamination of these oils should be carried out strictly according to local
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oSIST prEN IEC 60422:2023
– 8 – IEC CDV 60422 IEC 2023
43 regulations. Every precaution should be taken to prevent release of mineral oil into the
44 environment.
45 Typically, each country has specific regulations around health and safety. Safety Data Sheets
46 (SDS) are normally used by the industry internationally and are usually written in accordance
47 with an international regulation set (such as REACH). Please consult the SDS from the suppliers
48 of the insulating product that is used. These documents provide essential information regarding
49 health, safety, and environmental impacts.
50
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IEC CDV 60422 IEC 2023 – 9 –
51 MINERAL INSULATING OILS –
52 GUIDELINES FOR MAINTENANCE AND USE IN ELECTRICAL EQUIPMENT
53
54 1 Scope
55 This standard provides monitoring guidance and procedures that are required for the use and
56 maintenance of mineral insulating oils and other hydrocarbon-based liquids in transformers and
57 other electrical equipment.
58 This standard is applicable to mineral insulating oils, originally supplied conforming to
59 IEC 60296, in transformers, switchgear and other electrical apparatus where oil sampling is
60 reasonably practicable and where the normal operating conditions specified in the equipment
61 specifications apply.
62 This standard is also intended to assist the power equipment operator to evaluate the condition
63 of the oil and maintain it in a serviceable condition. It also provides a common basis for the
64 preparation of more specific and complete local codes of practice.
65 The standard includes recommendations on tests and evaluation procedures and outlines
66 methods for reconditioning and reclaiming oil and the decontamination of oil contaminated with
67 PCBs.
68 NOTE: The condition monitoring of electrical equipment, for example by analysis of dissolved gases, furanic
69 compounds or other means, is outside the scope of this standard.
70 2 Normative references
71 The following documents, in whole or in part, are normatively referenced in this document and
72 are indispensable for its application. For dated references, only the edition cited applies. For
73 undated references, the latest edition of the referenced document (including any amendments)
74 applies.
75 EN 12766-2, Petroleum products and used oils - Determination of PCBs and related products -
76 Part 2: Calculation of polychlorinated biphenyl (PCB) content
77 IEC 60156, Insulating liquids – Determination of the breakdown voltage at power frequency –
78 Test method
79 IEC 60247, Insulating liquids – Measurement of relative permittivity, dielectric dissipation factor
80 (tan δ) and d.c. resistivity
81 IEC 60296, Fluids for electrotechnical applications – Mineral insulating oils for electrical
82 equipment
83 IEC 60475, Method of sampling liquid dielectrics
84 IEC 60666, Detection and determination of specified additives in mineral insulating oils
85 IEC 60814, Insulating liquids – Oil-impregnated paper and pressboard – Determination of water
86 by automatic coulometric Karl Fischer titration
87 IEC 60970, Insulating liquids – Methods for counting and sizing particles
88 IEC 61125, Insulating liquids - Test methods for oxidation stability - Test method for evaluating
89 the oxidation stability of insulating liquids in the delivered state
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90 IEC 61619, Insulating liquids – Contamination by polychlorinated biphenyls (PCBs) – Method
91 of determination by capillary column gas chromatography
92 IEC 61620, Insulating liquids - Determination of the dielectric dissipation factor by measurement
93 of the conductance and capacitance - Test method
94 IEC 62021-1, Insulating liquids – Determination of acidity – Part 1: Automatic potentiometric
95 titration
96 IEC 62021-2, Insulating liquids – Determination of acidity – Part 2: Colourimetric titration
97 IEC 62535, Insulating liquids – Test method for detection of potentially corrosive sulph
...
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