IEC TR 61857-2:2015

Electrical insulation systems - Procedures for thermal evaluation - Part 2: Selection of the appropriate test method for evaluation and classification of electrical insulation systems

IEC TR 61857-2:2015(E) gives guidelines to identify the appropriate test method to be used for the evaluation of a proposed Electrical Insulation System (EIS). Some of the standards are for evaluation and classification of the EIS, while other standards identify the appropriate method to evaluate single or multi-factor stresses of a proposed or of an established EIS. This Technical Report is applicable to existing or proposed EIS used in electrotechnical products across a wide range of operating voltages of IEC Standards. The report takes care to select the appropriate standard based on construction and intended operating conditions.

General Information

• Status: Published
• Publication Date: 12-Apr-2015
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.080.30 - Insulation systems
• Technical Committee: TC 112 - Evaluation and qualification of electrical insulating materials and systems
• Drafting Committee: WG 6 - TC 112/WG 6
• Current Stage: PPUB - Publication issued
• Start Date: 30-Jun-2015
• Completion Date: 13-Apr-2015

Standards Content (Sample)

IEC TR 61857-2 ®
Edition 1.0 2015-04
TECHNICAL
REPORT
Electrical insulation systems – Procedures for thermal evaluation –
Part 2: Selection of the appropriate test method for evaluation and classification
of electrical insulation systems

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IEC TR 61857-2 ®
Edition 1.0 2015-04
TECHNICAL
REPORT
Electrical insulation systems – Procedures for thermal evaluation –

Part 2: Selection of the appropriate test method for evaluation and classification

of electrical insulation systems

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.080.30 ISBN 978-2-8322-2594-3

– 2 – IEC TR 61857-2:2015 © IEC 2015
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 General information . 6
4.1 Purpose of the evaluation . 6
4.2 Test objects . 7
4.3 Test stresses . 7
5 Design and development of the scope of work for the EIS evaluation. 7
6 Test methods for the evaluation and classification of EIS . 7

Table 1 – Evaluation for thermal stresses in air . 9
Table 2 – Standards for the modification of an established EIS . 10
Table 3 – Standards for special environmental applications . 10
Table 4 – For evaluation prior to the start of long-term thermal ageing . 10

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL INSULATION SYSTEMS –
PROCEDURES FOR THERMAL EVALUATION –

Part 2: Selection of the appropriate test method for evaluation
and classification of electrical insulation systems

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. However, a
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data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 61857-2, which is a technical report, has been prepared by IEC technical committee
112: Evaluation and qualification of electrical insulating materials and systems.

– 4 – IEC TR 61857-2:2015 © IEC 2015
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
112/312/DTR 112/318/RVC
Full information on the voting for the approval of this technical report 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.
A list of all parts in the IEC 61857 series, published under the general title Electrical insulation
systems – Procedures for thermal evaluation, can be found on the IEC website.
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.
A bilingual version of this publication may be issued at a later date.

ELECTRICAL INSULATION SYSTEMS –
PROCEDURES FOR THERMAL EVALUATION –

Part 2: Selection of the appropriate test method for evaluation
and classification of electrical insulation systems

1 Scope
This part of IEC 61857 gives guidelines to identify the appropriate test method to be used for
the evaluation of a proposed Electrical Insulation System (EIS). Some of the standards are for
evaluation and classification of the EIS, while other standards identify the appropriate method
to evaluate single or multi-factor stresses of a proposed or of an established EIS.
This Technical Report is applicable to existing or proposed EIS used in electrotechnical
products across a wide range of operating voltages of IEC Standards. The report takes care
to select the appropriate standard based on construction and intended operating conditions.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60034-18-21, Rotating electrical machines – Part 18-21: Functional evaluation of
insulation systems – Test procedures for wire-wound windings – Thermal evaluation and
classification
IEC 60034-18-31, Rotating electrical machines – Part 18-31: Functional evaluation of
insulation systems – Test procedures for form-wound windings – Thermal evaluation and
classification of insulation systems used in rotating machines
IEC 60505, Evaluation and qualification of electrical insulation systems
IEC 61857-1, Electrical insulation systems – Procedures for thermal evaluation – Part 1:
General requirements – Low-voltage
IEC 61857-21, Electrical insulation systems – Procedures for thermal evaluation – Part 21:
Specific requirements for general-purpose models – Wire-wound applications
IEC 61857-22, Electrical insulation systems – Procedures for thermal evaluation – Part 22:
Specific requirements for encapsulated-coil model – Wire-wound electrical insulation system
(EIS)
IEC 61858-1, Electrical insulation systems – Thermal evaluation of modifications to an
established electrical insulation system (EIS) – Part 1: Wire-wound winding EIS
IEC 61858-2, Electrical insulation systems – Thermal evaluation of modifications to an
established electrical insulation system (EIS) – Part 2: Form-wound EIS
IEC TS 61934, Electrical insulating materials and systems – Electrical measurement of partial
discharges (PD) under short rise time and repetitive voltage impulses

– 6 – IEC TR 61857-2:2015 © IEC 2015
IEC 62068, Electrical insulating materials and systems – General method of evaluation of
electrical endurance under repetitive voltage impulses
IEC TS 62101, Electrical insulation systems – Short-time evaluation of combined thermal and
electrical stresses
IEC TS 62332-1, Electrical insulation systems (EIS) – Thermal evaluation of combined liquid
and solid components – Part 1: General requirements
IEC TS 62332-2, Electrical insulation systems (EIS) – Thermal evaluation of combined liquid
and solid components – Part 2: Simplified test
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
completed product
production unit or prototype
EXAMPLE Such as the stator or rotor section of a rotating machine, a coil for a transformer or solenoid or similar
design which is a usable product.
3.2
test/lab model
test object constructed with all essential electrical insulating materials and processing
expected to be used in manufacturing of a completed product
3.3
rotating machinery
motor or generator
3.4
encapsulated device
electrotechnical device embedded in resin in order to ensure its safe operation
EXAMPLE Resin:
– as an integral component needed to provide safe operation of the electrotechnical device; and/or
– fills the void between the coil windings and metal parts which can be at earth (ground) potential; and/or
– in designs where the resin provides th
...