Rotating electrical machines - Part 18-32: Functional evaluation of insulation systems - Electrical endurance qualification procedures for form-wound windings

This part of IEC 60034-18 describes qualification procedures for the evaluation of electrical endurance of insulation systems for use in rotating electrical machines using form-wound windings. The test procedures are comparative in nature, such that the performance of a candidate insulation system is compared to that of a reference insulation system with proven service experience. If no reference system is available, the diagram in Annex A is available for use. The qualification procedures of inverter duty insulation system for form-wound windings can be found in IEC 60034-18-42 or IEC 60034-18-41.

Drehende elektrische Maschinen - Teil 18-32: Funktionelle Bewertung von Isoliersystemen - Prüfverfahren für Wicklungen mit vorgeformten Elementen - Bewertung der elektrischen Lebensdauer

Machines électriques tournantes - Partie 18-32: Evaluation fonctionnelle des systèmes d'isolation - Procédures d'essai pour enroulements préformés - Evaluation par endurance électrique

Električni rotacijski stroji - 18-32. del: Funkcionalno vrednotenje izolacijskih sistemov - Električno vrednotenje postopkov kvalificiranja za za predhodno oblikovana navitja

General Information

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Public Enquiry End Date
29-Nov-2020
Technical Committee
Current Stage
5020 - Formal vote (FV) (Adopted Project)
Start Date
07-Sep-2021
Due Date
26-Oct-2021

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SLOVENSKI STANDARD
oSIST prEN IEC 60034-18-32:2020
01-november-2020
Električni rotacijski stroji - 18-32. del: Funkcionalno vrednotenje izolacijskih
sistemov - Električno vrednotenje postopkov kvalificiranja za za predhodno
oblikovana navitja

Rotating electrical machines - Part 18-32: Functional evaluation of insulation systems -

Electrical endurance qualification procedures for form-wound windings
Drehende elektrische Maschinen - Teil 18-32: Funktionelle Bewertung von

Isoliersystemen - Prüfverfahren für Wicklungen mit vorgeformten Elementen - Bewertung

der elektrischen Lebensdauer

Machines électriques tournantes - Partie 18-32: Evaluation fonctionnelle des systèmes

d'isolation - Procédures d'essai pour enroulements préformés - Evaluation par
endurance électrique
Ta slovenski standard je istoveten z: prEN IEC 60034-18-32:2020
ICS:
29.080.30 Izolacijski sistemi Insulation systems
29.160.01 Rotacijski stroji na splošno Rotating machinery in
general
oSIST prEN IEC 60034-18-32:2020 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN IEC 60034-18-32:2020
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oSIST prEN IEC 60034-18-32:2020
2/2016/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60034-18-32 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2020-09-11 2020-12-04
SUPERSEDES DOCUMENTS:
2/1983/CD, 2/2001A/CC
IEC TC 2 : ROTATING MACHINERY
SECRETARIAT: SECRETARY:
United Kingdom Mr Charles Whitlock
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
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.
TITLE:

Rotating electrical machines – Part 18-32: Functional evaluation of insulation systems – Electrical endurance

qualification procedures for form-wound windings
PROPOSED STABILITY DATE: 2024
NOTE FROM TC/SC OFFICERS:

Copyright © 2020 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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oSIST prEN IEC 60034-18-32:2020
– 2 – IEC CDV 60034-18-32  IEC 2020
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope ............................................................................................................................... 7

2 Normative references ....................................................................................................... 7

3 Terms and definitions ....................................................................................................... 8

4 General considerations ..................................................................................................... 8

4.1 Relationship to IEC 60034-18-1 ............................................................................... 8

4.2 Selection and designation of test procedures .......................................................... 8

4.3 Reference insulation system .................................................................................... 9

4.4 Test procedures ...................................................................................................... 9

4.4.1 General ....................................................................................................... 9

4.4.2 Electrical ageing of the mainwall insulation .................................................. 9

4.4.3 Electrical ageing of the conductive slot coating ............................................ 9

4.4.4 Electrical ageing of the stress control coating ............................................ 10

4.4.5 Electrical ageing of the turn insulation ....................................................... 10

4.5 Extent of tests ....................................................................................................... 10

4.5.1 Full evaluation of the mainwall insulation ................................................... 10

4.5.2 Reduced evaluation of the mainwall insulation ........................................... 10

4.5.3 Evaluation of the conductive slot coating ................................................... 10

4.5.4 Evaluation of the stress control coating ..................................................... 10

5 Test objects .................................................................................................................... 11

5.1 Construction of test objects ................................................................................... 11

5.2 Number of test specimens ..................................................................................... 11

5.3 Initial quality control tests ...................................................................................... 11

6 Electrical ageing ............................................................................................................. 12

6.1 General ................................................................................................................. 12

6.2 Voltage levels and intended test lives of the mainwall insulation ............................ 12

6.3 Test temperatures during electrical endurance testing of the mainwall

insulation............................................................................................................... 12

6.3.1 Electrical ageing at room temperature ....................................................... 12

6.3.2 Electrical ageing at elevated temperature .................................................. 12

6.3.3 Ageing procedure for the mainwall insulation ............................................. 12

6.4 Ageing procedure for the conductive slot and stress control coating ...................... 13

6.4.1 Arrangement of temperature control by heater plates ................................ 13

6.4.2 Heating by means of an oven .................................................................... 13

6.4.3 Test parameter .......................................................................................... 13

6.5 Maintenance of stress control coatings .................................................................. 14

7 Diagnostic sub-cycle ...................................................................................................... 14

7.1 General ................................................................................................................. 14

7.2 Voltage test of the mainwall insulation ................................................................... 14

7.3 Other diagnostic tests............................................................................................ 15

8 Failures of the mainwall insulation .................................................................................. 15

8.1 Failure location and verification ............................................................................. 15

8.2 Failed specimen observations ............................................................................... 15

9 Qualification of the stress control system........................................................................ 15

9.1 Test procedure ...................................................................................................... 15

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IEC CDV 60034-18-32  IEC 2020 – 3 –

9.2 Test pass criteria .................................................................................................. 15

10 Functional evaluation of the mainwall data ..................................................................... 16

10.1 General ................................................................................................................. 16

10.2 Full evaluation (same voltage level and same expected service life) ...................... 16

10.3 Reduced evaluation (same voltage level and same expected service life).............. 18

10.4 Recommended data to be recorded ....................................................................... 19

10.5 Determining qualification for performances different to the reference system ......... 20

10.5.1 Overview ................................................................................................... 20

10.5.2 Case B: Qualification for the same phase to phase voltage and a

different expected service life .................................................................... 20

10.5.3 Case C: Qualification for different voltage level and same expected

service life ................................................................................................. 21

10.5.4 Case D: Qualification for different voltage level and different

expected service life .................................................................................. 22

10.5.5 Non-linearity of regression lines ................................................................ 23

Annex A Reference life line for mainwall insulation in the absence of a manufacturer’s

reference life line ............................................................................................................ 24

Annex B Examples for deterioration marks at the stress control system ................................ 25

Figure 1 – Application of heater elements to a stator bar ...................................................... 13

Figure 2 – Comparison of ageing data from candidate (C) and reference (R) insulation

systems showing qualification ............................................................................................... 17

Figure 3 – Comparison of ageing data from candidate and reference insulation systems

showing failure to qualify ...................................................................................................... 18

Figure 4 – Comparison of reduced evaluation test data from four separate candidate

systems with that from the reference system ......................................................................... 19

Figure 5 – Candidate system qualified for the same voltage level and different

expected service life ............................................................................................................. 21

Figure 6 – Candidate system qualified for a higher voltage level and the same

expected service life ............................................................................................................. 22

Figure 7 – Candidate system qualified for a different service life and different voltage

level from the reference ........................................................................................................ 23

Figure A.1: Reference lifeline for mainwall insulation ............................................................ 24

Picture B.1: Typical deterioration mark at the conductive slot coating ................................... 25

Table 1 – Phase to ground test voltages in relation to temperature at operating

condition ............................................................................................................................... 14

Table 2 – Conditions for qualification of candidate system .................................................... 20

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oSIST prEN IEC 60034-18-32:2020
– 4 – IEC CDV 60034-18-32  IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ROTATING ELECTRICAL MACHINES –
Part 18-32: Functional evaluation of insulation systems (Type II) –
Electrical endurance qualification procedures for form-wound windings
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,

Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their

preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with

may participate in this preparatory work. International, governmental and non-governmental organizations liaising

with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for

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

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

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

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

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

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

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 60034-18-32 has been prepared by IEC technical committee 2: Rotating machinery.

This third edition cancels and replaces the second edition issued in 2010 and constitutes a technical revision.

The main technical changes with regard to the previous edition are as follows.
a) Simplification of clauses
b) Reduction in the number of test procedures
c) Inclusion of full bars and coils as test objects
d) A new clause dealing with failures and failure criteria
The text of this standard is based on the following documents:
FDIS Report on voting
2/XX/FDIS 2/XX/RVD

Full information on the voting for the approval of this International Standard can be found in the

report on voting indicated in the above table.
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oSIST prEN IEC 60034-18-32:2020
IEC CDV 60034-18-32  IEC 2020 – 5 –

The committee has decided that the contents of this publication will remain unchanged until the

maintenance result 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.

NOTE A table of cross-references of all IEC TC2 publications can be found in the IEC TC2 dashboard on the IEC

website.
—————————

The National Committees are requested to note that for this publication the maintenance result date is ....

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oSIST prEN IEC 60034-18-32:2020
– 6 – IEC CDV 60034-18-32  IEC 2020
1 INTRODUCTION

2 Part 1 of IEC 60034-18 presents general principles for the evaluation of insulation systems used

3 in rotating electrical machines.

4 This Standard deals exclusively with insulation systems for form-wound windings (Type II) and

5 concentrates on electrical functional evaluation.

6 In IEC 60034-18-42, tests are described for qualification of Type II insulation systems in

7 voltage-source converter operation. These insulation systems are generally used in rotating

8 machines which have form-wound windings, mostly rated above 700 V r.m.s. The two standards

9 IEC 60034-18-41 and IEC 60034-18-42 separate the systems into those which are not expected

10 to experience partial discharge activity within specified conditions in their service lives (Type I)

11 and those which are expected to experience and withstand partial discharge activity in any part

12 of the insulation system throughout their service lives (Type II).
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oSIST prEN IEC 60034-18-32:2020
IEC CDV 60034-18-32  IEC 2020 – 7 –
14 ROTATING ELECTRICAL MACHINES –
16 Part 18-32: Functional evaluation of insulation systems –
17 Electrical endurance qualification procedures for form-wound windings
19 1 Scope

20 This part of IEC 60034-18 describes qualification procedures for the evaluation of electrical

21 endurance of insulation systems for use in rotating electrical machines using form-wound

22 windings. The test procedures are comparative in nature, such that the performance of a

23 candidate insulation system is compared to that of a reference insulation system with proven

24 service experience. If no reference system is available, the diagram in Annex A is available for

25 use. The qualification procedures of inverter duty insulation system for form-wound windings

26 can be found in IEC 60034-18-42 or IEC 60034-18-41.
27 2 Normative references

28 The following referenced documents are indispensable for the application of this document. For

29 dated references, only the edition cited applies. For undated references, the latest edition of

30 the referenced document (including any amendments) applies.
31 IEC 60034-1: Rotating electrical machines – Part 1: Rating and performance

32 IEC 60034-15: 2009, Rotating electrical machines – Part 15: Impulse voltage withstand

33 levels of form-wound stator coils for rotating a.c. machines

34 IEC 60034-18-1: 2010, Rotating electrical machines – Part 18-1: Functional evaluation of

35 insulation systems – General guidelines Amendment 1 (1996)

36 IEC 60034-18-33: Rotating electrical machines – Part 18-33: Functional evaluation of in-

37 sulation systems – Test procedures for multifunctional evaluation of form-wound windings

38 by endurance under combined thermal and electrical stresses of insulation systems used in

39 rotating machines

40 IEC 60034-18-41: Rotating electrical machines – Part 18-41: Partial discharge free electrical

41 insulation systems (Type I) used in rotating electrical machines fed from voltage converters –

42 Qualification and quality control tests (IEC 60034-18-41:2014)

43 IEC 60034-18-42: Rotating electrical machines – Part 18-42: Qualification and acceptance

44 tests for partial discharge resistant electrical insulation systems (Type II) used in rotating

45 electrical machines fed from voltage converters

46 IEC 61251 Electrical insulating materials – A.C. voltage endurance evaluation – Introduction

47 IEC 62539: Guide for the statistical analysis of electrical insulation breakdown data

48 IEC 60034-18-31: Rotating electrical machines – Part 18-31: Functional evaluation of

49 insulation systems – Test procedures for form-wound windings – Thermal evaluation and

50 classification of insulation systems used in rotating machines
51 IEC 60505: Evaluation and qualification of electrical insulation systems

52 IEC 60034-27-1: Rotating electrical machines – Part 27-1: Off-line partial discharge

53 measurements on the winding insulation

54 IEC 60034-27-3: Rotating electrical machines – Part 27-3: Dielectric dissipation factor

55 measurements on stator winding insulation of rotating electrical machines
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oSIST prEN IEC 60034-18-32:2020
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56 3 Terms and definitions
57 For the purposes of this document, the following terms and definitions apply.
58 3.1
59 mainwall insulation

60 main electrical insulation that separates the conductors from the earthed stator/rotor core in

61 motor and generator windings
62 3.2
63 strand insulation
64 electrical insulation that covers each conductor in coils/bars
65 3.3
66 turn insulation

67 electrical insulation that separates the conductor turns from each other in coils/bars

68 3.4
69 conductive slot coating

70 conductive paint or tape layer in intimate contact with the mainwall insulation in the slot portion

71 of the coil side, often called semi-conductive coating

72 Note 1 to entry: The purpose is to prevent partial discharge from occurring between the coil/bar and the stator core.

73 3.5
74 stress control coating

75 paint or tape on the surface of the mainwall insulation that extends beyond the conductive slot

76 coating in high-voltage stator bars and coils

77 Note 2 to entry: The purpose of the coating is to prevent surface discharges in the end winding area.

78 3.6
79 stress control system

80 generic name for the combination of the conductive slot coating and stress control coating in

81 high-voltage stator bars and coils
82 3.7
83 confidence interval

84 a range of values so defined that there is a specified probability that the value of a parameter

85 (voltage, stress or time) lies within it
86 3.8
87 test temperature

88 is the temperature measured by temperature sensors either under the grounding plates or at

89 the specimens surface (oven heating) at the straight part of the coil/bar
90 4 General considerations
91 4.1 Relationship to IEC 60034-18-1

92 The principles of Part 1 of IEC 60034-18 should be followed unless the recommendations of

93 this International Standard indicate otherwise.
94 4.2 Selection and designation of test procedures

95 One or more of the procedures in this International Standard should be suitable for the majority

96 of evaluations. Evaluation is usually performed by the manufacturer of the machine/coils or by

97 a third party laboratory. It is the manufacturer’s responsibility to justify the most suitable

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oSIST prEN IEC 60034-18-32:2020
IEC CDV 60034-18-32  IEC 2020 – 9 –

98 procedure on the basis of past experience and knowledge of the insulation systems to be

99 compared.
100 Following test procedures are described:
101 • Mainwall insulation
102 • Turn insulation only together with the main insulation test
103 • Conductive slot coating
104 • Stress control coating

105 • Mainwall insulation, where voltage level and/or life time differs from the reference

106 system
107 4.3 Reference insulation system

108 A reference insulation system should be tested using a test procedure equivalent to that used

109 for the candidate system (see IEC 60034-18-1). The reference insulation system should have

110 service experience at not less than 75 % of the intended maximum rated voltage of the

111 candidate system. When extrapolation of the insulation thickness is used, information such as

112 “different insulation thickness at same electrical field stress levels by obtaining equal or similar

113 breakdown time” should be provided showing the correlation between electrical lifetime and

114 electrical stress for the different insulation thicknesses. If no reference insulation system is

115 available the diagram in Annex A shall be used as criterion.
116 4.4 Test procedures
117 4.4.1 General

118 Electrical ageing tests are usually performed at fixed voltage levels until failure (mainwall

119 insulation) or in combination with elevated temperature until signs of deterioration occur

120 (conductive slot coating system). Statistical evaluation of the results of testing should be

121 performed according to IEC 62539.
122 4.4.2 Electrical ageing of the mainwall insulation

123 From such tests, characteristic times to failure at each voltage level are obtained. The results

124 for both the candidate system and the reference system should be reported on a graph, as

125 shown by the example in Figure 2, and compared. There is no proven physical basis for

126 extrapolation of this characteristic to the service voltage level 𝑈𝑈 √3, where UN is the r.m.s.

𝑁𝑁
127 rated phase to phase voltage.

128 In service, electrical ageing of the mainwall insulation is primarily caused by continuous elec-

129 trical stress at power frequency. In addition, the insulation is required to withstand transient

130 overvoltages arising from switching surges or inverter supply. The ability of the mainwall

131 insulation to withstand transient overvoltages from converter supplies may be demonstrated by

132 the system’s performance using IEC 60034-18-42.

133 This standard describes electrical ageing of the mainwall insulation, carried out at power

134 frequency or higher. In order to keep acceleration of ageing in a linear progression, a maximum

135 of 10 times of the power frequencies is appropriate. Latest experiences with the application of

136 60034-18-42 show that a frequency of up to 1000 Hz ca ben used as well. Care shall be taken

137 that the dielectric losses do not increase the temperature of the insulation beyond the service

138 temperature to avoid additional thermal ageing effects. (IEC 60034-18-33 table 1)

139 4.4.3 Electrical ageing of the conductive slot coating

140 Ageing of conductive slot coating can be described as a successive degradation of the

141 conductive material caused by partial discharges. The conductive slot coating system shows a

142 notable dependency not only of the electrical field strength, but also of the applied temperature

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oSIST prEN IEC 60034-18-32:2020
– 10 – IEC CDV 60034-18-32  IEC 2020

143 in operation and absolute voltage level. It is therefore associated as multifactor ageing.

144 Additionally, larger voltage variations at the terminals as well as ambient stresses like ozone

145 may additionally affect the conductive slot coating, but these additional ageing factors are not

146 part of the qualification.

147 This standard describes electrical ageing under elevated temperature of the conductive slot

148 coating carried out at power frequency.
149 4.4.4 Electrical ageing of the stress control coating

150 Ageing of the stress control coating can be described as deterioration by either too excessive

151 surface electrical stress, too high temperatures or a combination of both. Furthermore ageing

152 of the stress control coating is also deteriorated by inadequate contact between stress control

153 coating and conductive slot coating.
154 4.4.5 Electrical ageing of the turn insulation

155 In normal direct-on-line operation of rotating machines the turn insulation is subjected to a

156 stress significantly below the partial discharge inception voltage. Continuous electrical ageing

157 is then not taking place and turn insulation qualification is therefore excluded from this

158 document. Withstand against transient overvoltages should be tested according to

159 IEC 60034-15.

160 In converter fed or other types of special operation the turn insulation may continuously be

161 subjected to a stress above the partial discharge inception voltage. Electrical ageing should

162 then be performed according to IEC 60034-18-42.
163
164 4.5 Extent of tests
165 4.5.1 Full evaluation of the mainwall insulation

166 The extent of the electrical functional tests will depend upon the purpose of the evaluation. A

167 full evaluation will be needed where there are substantial differences according to

168 IEC 60034-18-1.
169
...

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