IEC 60034-18-42:2017/AMD1:2020

Amendment 1 - Rotating electrical machines - Part 18-42: Partial discharge resistant electrical insulation systems (Type II) used in rotating electrical machines fed from voltage converters - Qualification tests

Amendement 1 - Machines électriques tournantes - Partie 18-42: Systèmes d'isolation électrique résistants aux décharges partielles (Type II) utilisés dans des machines électriques tournantes alimentées par convertisseurs de tension - Essais de qualification

General Information

• Status: Published
• Publication Date: 17-Aug-2020
• ICS: 29.160.01 - Rotating machinery in general
• Technical Committee: TC 2 - Rotating machinery
• Drafting Committee: MT 10 - TC 2/MT 10
• Current Stage: PPUB - Publication issued
• Start Date: 18-Aug-2020
• Completion Date: 07-Aug-2020

Relations

• Amends: IEC 60034-18-42:2017 - Rotating electrical machines - Part 18-42: Partial discharge resistant electrical insulation systems (Type II) used in rotating electrical machines fed from voltage converters - Qualification tests
• Effective Date: 05-Sep-2023

Overview

IEC 60034-18-42:2017/AMD1:2020 is an important amendment to the IEC 60034-18-42 standard, which addresses the qualification tests for partial discharge resistant electrical insulation systems (Type II) used in rotating electrical machines powered by voltage converters. Published by the International Electrotechnical Commission (IEC), this amendment refines and updates testing methods and definitions that ensure the reliability and longevity of insulation systems under converter-fed conditions.

This standard plays a critical role in the design, testing, and certification of rotating electrical machines, safeguarding against insulation failures caused by partial discharges when subjected to electrical stress from modern power electronics.

Key Topics

• Partial discharge resistant insulation: Focuses on Type II insulation systems designed for rotating machines powered by voltage converters, which typically produce unique electrical stresses not present in traditional line-fed machines.

• Qualification tests: Specifies rigorous procedures to evaluate electrical insulation’s durability and resistance against partial discharges, ensuring insulation systems maintain performance and safety over their expected operational lifetime.

• Impulse voltage insulation classes (IVIC): Defines standardized classes and corresponding test voltage factors (TVF) which account for enhanced voltage stresses caused by converter-fed operation. Manufacturers assign IVIC ratings to their insulation systems based on rigorous testing.

• Test voltage and stress criteria: Introduces quantitative voltage parameters including maximum allowable peak-to-peak operating voltages and jump voltages at impulse repetition rates to simulate real-world electrical conditions in qualification testing.

• Stress control specimens: Describes test set-ups using coils or bars fitted in simulated slots with controlled heating, replicating operation temperatures and electrical stresses to reliably assess insulation life.

• Pass criteria for mainwall insulation: Standardizes life expectancy tests comparing candidate insulation systems with proven reference systems, taking statistical confidence intervals into account to ensure consistent quality.

• Optional screening tests: Presents short-term endurance tests serving as quality checks for production insulation systems; these are not mandatory type tests but offer valuable insights into insulation robustness before service.

Applications

• Rotating electrical machines in industrial settings: Especially relevant to motors and generators driven by voltage converters such as variable frequency drives (VFDs), where electrical insulation must withstand high-frequency voltage impulses and repeated stress.

• Renewable energy equipment: Wind turbines and hydroelectric generators benefit from insulation systems tested under IEC 60034-18-42 guidelines to endure converter-induced stresses, enhancing reliability.

• Power plants and heavy machinery: Steam and gas turbines require insulation systems with verified partial discharge resistance to ensure long-term electrical and mechanical reliability under demanding operational conditions.

• Electrical insulation manufacturers: Utilizes this standard to develop, test, and certify Type II insulation products intended for converter-fed rotating machines, meeting international requirements and customer expectations.

• Testing laboratories: Implements qualification tests and optional screening as per IEC 60034-18-42 to validate insulation systems, supporting manufacturers and end-users with certified assurance.

Related Standards

• IEC 60034-1: General standard for rotating electrical machines, providing foundational voltage ratings and test procedures used alongside IEC 60034-18-42.

• IEC 60034-18-1: Provides mainwall insulation life tests at fundamental frequencies, serving as a reference for the performance comparison required in IEC 60034-18-42.

• IEC 60034-18-32: Specifies qualification requirements for the mainwall insulation of converter-fed rotating machines complementing the partial discharge resistance focus of Part 18-42.

• IEC 60034 series: Covers various aspects of rotating electrical machines including design, testing, and performance criteria.

• IEC Electropedia and IEC Glossary: Authoritative sources of electrotechnical terminology referenced for precise definitions in the standard.

---

Keywords: IEC 60034-18-42 amendment, partial discharge resistant insulation, Type II insulation systems, rotating electrical machines, voltage converters, qualification tests, impulse voltage insulation class (IVIC), test voltage factor (TVF), mainwall insulation, converter-fed motors, electrical insulation testing, rotating machinery standards.

Standards Content (Sample)

IEC 60034-18-42 ®
Edition 1.0 2020-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
A MENDMENT 1
AM ENDEMENT 1
Rotating electrical machines –
Part 18-42: Partial discharge resistant electrical insulation systems (Type II)
used in rotating electrical machines fed from voltage converters – Qualification
tests
Machines électriques tournantes –
Partie 18-42: Systèmes d’isolation électrique résistants aux décharges partielles
(Type II) utilisés dans des machines électriques tournantes alimentées par
convertisseurs de tension – Essais de qualification

IEC 60034-18-42:2017-02/AMD1:2020-08(en-fr)

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite
ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie
et les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des
questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez
les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Central Office Tel.: [phone]
3, rue de Varembé [e-mail]
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
details all new publications released. Available online and 67 000 electrotechnical terminology entries in English and
once a month by email. French extracted from the Terms and definitions clause of
IEC publications issued between 2002 and 2015. Some
IEC Customer Service Centre - webstore.iec.ch/csc entries have been collected from earlier publications of IEC
If you wish to give us your feedback on this publication or TC 37, 77, 86 and CISPR.

need further assistance, please contact the Customer Service

Centre: [e-mail].
A propos de l'IEC
La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des
Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC
Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la
plus récente, un corrigendum ou amendement peut avoir été publié.

Recherche de publications IEC - Electropedia - www.electropedia.org
webstore.iec.ch/advsearchform Le premier dictionnaire d'électrotechnologie en ligne au
La recherche avancée permet de trouver des publications IEC monde, avec plus de 22 000 articles terminologiques en
en utilisant différents critères (numéro de référence, texte, anglais et en français, ainsi que les termes équivalents dans
comité d’études,…). Elle donne aussi des informations sur les 16 langues additionnelles. Egalement appelé Vocabulaire
projets et les publications remplacées ou retirées. Electrotechnique International (IEV) en ligne.

IEC Just Published - webstore.iec.ch/justpublished Glossaire IEC - std.iec.ch/glossary
Restez informé sur les nouvelles publications IEC. Just 67 000 entrées terminologiques électrotechniques, en anglais
Published détaille les nouvelles publications parues. et en français, extraites des articles Termes et définitions des
Disponible en ligne et une fois par mois par email. publications IEC parues entre 2002 et 2015. Plus certaines
entrées antérieures extraites des publications des CE 37, 77,
Service Clients - webstore.iec.ch/csc 86 et CISPR de l'IEC.

Si vous désirez nous donner des commentaires sur cette
publication ou si vous avez des questions contactez-nous:
[e-mail].
IEC 60034-18-42 ®
Edition 1.0 2020-08
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
A MENDMENT 1
AM ENDEMENT 1
Rotating electrical machines –

Part 18-42: Partial discharge resistant electrical insulation systems (Type II)

used in rotating electrical machines fed from voltage converters – Qualification

tests
Machines électriques tournantes –

Partie 18-42: Systèmes d’isolation électrique résistants aux décharges partielles

(Type II) utilisés dans des machines électriques tournantes alimentées par

convertisseurs de tension – Essais de qualification

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.160.01 ISBN 978-2-8322-8603-6

– 2 – IEC 60034-18-42:2017/AMD1:2020
© IEC 2020
FOREWORD
This amendment has been prepared by IEC Technical Committee 2: Rotating machinery.
The text of this amendment is based on the following documents:
FDIS Report on voting
2/1998/FDIS 2/2008/RVD
Full information on the voting for the approval of this amendment can be found in the report on
voting indicated in the above table.
The committee has decided that the contents of this publication will remain unchanged until the
stability date indicated on the IEC website 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.
_____________
3 Terms and definitions
Replace the existing definitions with the following new definitions:
3.11
impulse voltage repetition rate
f
average of the inverse of the time between two successive impulses of the same polarity,
whether unipolar or bipolar, in a considered set of pulses, for example for one period
3.18
impulse voltage insulation class for Type II insulation systems
IVIC
peak to peak voltage classes 1, 2, 3, 4, 5, 6, 7, S including certain time parameters for reliable
operation, assigned by the manufacturer in relation to the rated voltage for a specified
converter-driven machine and indicated in its documentation and, if applicable, on its rating
plate
3.29
maximum allowable peak to peak phase to ground voltage
U
IVIC
maximum allowable peak to peak phase to ground voltage in service, according to the IVIC-
specification
© IEC 2020
Add the following new definition:
3.30
test voltage factor
TVF
maximum allowable peak to peak operating phase-ground-voltages in units of U , divided by
N
2√2
Replace the existing Table 1 with the following:
Table 1 – Examples of the measured values of the characteristics
of the terminal voltages for two converter-fed machines
Machine rating 3,3 kV 6,6 kV
Measured peak to peak voltage on the phase to ground insulation 7,9 kV 13,9 kV
Fundamental frequency 50/60 Hz 50/60 Hz
Impulse rise time at the motor terminals 1 µs 3 µs
Impulse repetition rate 1 kHz 900 Hz
IVIC required to qualify the insulation for this service (see Table D.2, column 2) 3 2

Replace the second paragraph below Table 1 with the following:
The maximum change in voltage or jump voltage (U ) at the impulse repetition rate is shown in
j
Figure 3. This parameter is important in defining the voltage enhancement that can occur across
the first or last coil in the winding. A fundamental frequent double jump transition
(Figure 3, U )) is possible and needs to be considered accordingly.
j max
– 4 – IEC 60034-18-42:2017/AMD1:2020
© IEC 2020
Replace Figure 3 with the following:

Figure 3 – Jump voltage (U or U ) at the terminals
j j max
of a machine fed from a converter drive
10.2 Test methods
Replace the fist paragraph with the following:
The purpose of testing is to show that the electrical life of the turn insulation provides a life in
service which is acceptable to the customer. It is expected that the manufacturer will know the
maximum peak to peak voltage to appear between turns in a particular service application. The
worst case insulation stress (depending on winding and coil design) shall be chosen. If the
maximum peak to peak voltage between turns in service U is unknown, it shall be assumed
turn
that the complete jump voltage falls across the first coil, and so the amplitude of U is the
turn
jump voltage divided by the number of turns (for one layer coils) or calculated according to the
arrangement of turns (for multilayer coils). The peak-peak turn-turn voltage is normally twice
the amplitude –if the rise time and the fall time of the jumps are usually the same.
12.4 Stress control specimens
Replace the text of this subclause with the following:
To qualify the stress control system to be used, testing of coils or bars, built to production
standards and fitted into representative slots, is undertaken. The slots shall be equipped with
heaters for the heating of the straight part to service temperature. Heating may be produced by
passing current through the conductors. In order to reduce the capacitive load on the test
supply, the specimens and slots may be of reduced length but the specimens shall otherwise
be manufactured in the same way as the coils or bars used in service. Supplemental heating
by thermostatic chamber or other heating devices may be applied for the stable heating.
Supplemental heating temperature should be below the operating temperature of stator coils –
see Clause 7.
© IEC 2020
13.2 Mainwall insulation
Replace the second paragraph with the following.
At least three voltages shall be selected and the end-point is when electrical breakdown of the
insulation takes place. At least seven separate bars or coil legs shall be tested at each voltage,
using pass criterion a) or b) (see 14.1 below). If pass criterion c) is to be applied, at least four
separate bars or coil legs shall be tested at each voltage. The life line for the candidate
insulation system is compared with the reference life curve, i.e. one that has been derived from
an insulation system that has been shown to provide an acceptable service life at the
fundamental frequency (IEC 60034-18-1). The reference life line may have been obtained from
satisfactory service life under converter drive.
14 Qualification test pass criteria
Replace subclause 14.1 with the following:
14.1 Mainwall insulation
Comparison between the candidate and reference life lines shall be at the same frequency. Any
corrections for a different frequency used in testing shall be undertaken according to 9.3 before
the comparison is made. The mainwall insulation is qualified according to IEC 60034-18-32 if
a) the upper 90 % confidence limit of the candidate system life line exceeds the upper 90 %
confidence limit of the reference mainwall insulation life line over the same test voltages; or
b) the lower 90 % confidence limit of the candidate system life line exceeds or is equal to the
lower 90 % confidence limit of the reference mainwall insulation life line at the lowest test
voltage and the slope of the regression line of the mean values of the candidate system life
line is steeper than that of the reference mainwall insulation life line (i.e. the value of n for
the candidate system is greater than for the reference system);
c) if there are no confidence intervals available from the reference system – for example the
reference line in Annex E – the pass criterion for the candidate system shall be that not
more than one of the specimens at each voltage has a lifetime less than indicated by the
reference line (see E.1.1). If one sample of the four falls below the reference line, then at
least two more specimens have to be tested and pass. [15]

– 6 – IEC 60034-18-42:2017/AMD1:2020
© IEC 2020
Annex D
Replace Table D.1 with the following:
Table D.1 – IVIC- and test voltage factor definition for Type II insulation systems
IVIC Maximum TVF Maximum allowable Examples of r.m.s. routine test
allowable enhancement ratio for the voltages at 50/60 Hz
operating peak- phase to ground peak to
(U = 6,6 kV)
peak-phase- peak voltage N
ground-voltages
Converter fed Line fed
(U ) in units of
IVIC
U
N
None (line) 1,6 - 1,0 - 14,2
1 1,8 1,0 1,1 14,2 -
2 2,1 1,0 1,3 14,2 -
3 2,4 1,0 1,5 14,2 -
4 2,8 1,0 1,7 14,2 -
5 3,3 1,2 2,0 16,4 -
6 3,8 1,3 2,3 18,5 -
7 4,2 1,5 2,6 20,8 -
S (manufacture Y  Y Y√3 TVF × 2 U +1 kV -
N
specified)
2√2 2√2
NOTE 1 Enhancement ratio is the phase-ground peak to peak machine terminal voltage under converter operation divided
by the phase-ground peak to peak machine terminal voltage under normal line operation. The latter one is being calculated
by U ××2
N
NOTE 2 The value Y = U /U – as it is used in 60034-18-41, is chosen by the manufacturer, specifying different values
IVIC N
of U than given in the second column, using IVIC S.
IVIC
NOTE 3 14,2 kV is the test voltage specified by IEC 60034-1 for U = 6,6 kV.
N
NOTE 4 The test voltage is defined only by the maximum allowable peak to peak voltage at the motor terminals in
operation. Other differences in the voltage waveform in operation are not taken into consideration.
NOTE 5 The formulas in the line of IVIC “S” apply to the other IVICs 1…7 as well.

© IEC 2020
Replace Table D.2 with the following:
Table D.2 – Impulse voltage insulation classes (IVIC)
Impulse voltage insulation classes for Type II insulation systems – Severity codes and limiting values
Independent parameters of the IVIC
Phase to ground machine terminal voltage Phase to ground impulse voltage
Maximum allowable Maximum allowable Ratio of the maximum allowable Maximum allowable Minimum allowable phase
enhancement ratio for fundamental frequency jump voltage to the maximum impulse voltage repetition to ground impulse
the voltage  allowable phase to ground peak to rate (f) voltage rise time (t )
r
peak voltage
IVIC
(Column 1) (Column 2) (Column 3) (Column 4)
(Column 5)
Maximum U converter
pk/pk
operation divided by
U direct on line U /U
Hz kHz µs
pk/pk j pk/pk
operation
√3(U /U )/2√2
IVIC N
1 1,1
2 1,3
3 1,5
4 1,7
Value to be reported in the Value to be reported in the Value to be reported in the Value to be reported in the
5 2,0
documentation documentation documentation documentation
6 2,3
7 2,6
To be chosen by the
S
manufacturer
Severity code
– 8 – IEC 60034-18-42:2017/AMD1:2020
© IEC 2020
Annex E
E.1.1 Mainwall insulation
Replace the first paragraph below Figure E.1 with the following:
Comparison of the measured lifetimes shall be against the reference life line shown in
Figure E.1. This life line reflects the electrical ageing at room temperature. It is consistent with
those measured at 50 Hz or 60 Hz from mica/epoxy resin systems that have been shown to give
reliable lives in service [16,17,18]. It is valid for an expected design life time of very large
machines in steam, gas or hydro power plants, for example of 40 years.

© IEC 2020
Replace Annex F with the following.
Annex F
(informative)
Optional screening tests
F.1 General
Tests are described
...