Electrical insulation systems (EIS) - Thermal evaluation of combined liquid and solid components - Part 2: Simplified test

IEC TS 62332-2:2014 is applicable to EIS containing solid and liquid components where the thermal stress is the dominant ageing factor, without restriction to voltage class. This part specifies a sealed tube test procedure for the thermal evaluation and qualification of electrical insulation systems (EIS). One aspect of this procedure is to also provide a method to assign thermal classifications to materials used in EIS where solid and liquid components are both used. This procedure describes a comparative ageing method whereby a reference system composed of kraft paper and mineral oil is compared to a candidate system of any combination of solid and insulating liquid. The test procedures in this part are specifically applicable to liquid immersed transformer insulation systems.

Systèmes d'isolation électrique (SIE) - Evaluation thermique de composants liquides et solides combinés - Partie 2: Essai simplifié

L'IEC TS 62332-2:2014 est applicable aux SIE contenant des composants solides et liquides, où la contrainte thermique est le facteur de vieillissement prédominant, sans restriction de la classe de tension. La présente partie indique une procédure d'essai à tube scellé pour l'évaluation et la qualification thermiques des systèmes d'isolation électrique (SIE). Un aspect de cette procédure est également de fournir une méthode d'attribution de classifications thermiques aux matériaux utilisés dans les SIE qui utilisent tant des composants solides que des composants liquides. Cette procédure décrit une méthode de vieillissement comparative où un système de référence composé de papier kraft et d'huile minérale est comparé à un système candidat de toute combinaison de composant solide et de liquide isolant. Les procédures d'essai décrites dans la présente partie s'appliquent spécifiquement aux systèmes d'isolation à transformateurs de puissance immergés dans un liquide.

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Status
Published
Publication Date
23-Apr-2014
Current Stage
PPUB - Publication issued
Start Date
24-Apr-2014
Completion Date
24-Apr-2014
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IEC TS 62332-2
Edition 1.0 2014-04
TECHNICAL
SPECIFICATION
SPECIFICATION
TECHNIQUE
colour
inside
Electrical insulation systems (EIS) –Thermal evaluation of combined liquid and
solid components –
Part 2: Simplified test
Systèmes d'isolation électrique (SIE) – Évaluation thermique de composants
liquides et solides combines –
Partie 2: Essai simplifié
IEC TS 62332-2:2014-04(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TS 62332-2
Edition 1.0 2014-04
TECHNICAL
SPECIFICATION
SPECIFICATION
TECHNIQUE
colour
inside
Electrical insulation systems (EIS) –Thermal evaluation of combined liquid and
solid components –
Part 2: Simplified test
Systèmes d'isolation électrique (SIE) – Évaluation thermique de composants
liquides et solides combines –
Partie 2: Essai simplifié
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX T
ICS 29.080.30 ISBN 978-2-8322-1514-2

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC TS 62332-2:2014 © IEC 2014
CONTENTS

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

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

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

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

3 Terms and definitions ...................................................................................................... 9

4 Thermal ageing test apparatus ...................................................................................... 10

4.1 General description ............................................................................................... 10

4.2 Sealed tubes ......................................................................................................... 10

4.3 Gas blanketing system .......................................................................................... 11

4.4 Pressure relief system .......................................................................................... 11

4.5 Ageing ovens ........................................................................................................ 11

5 Construction of the test object ....................................................................................... 12

5.1 General ................................................................................................................. 12

5.2 Determination of component weights..................................................................... 12

5.3 Test object ............................................................................................................ 12

5.3.1 Conductor insulation ...................................................................................... 12

5.3.2 Other solid insulation components ................................................................. 13

5.3.3 Liquid component .......................................................................................... 13

5.3.4 Structural components ................................................................................... 13

5.3.5 Other components ......................................................................................... 13

6 Test procedures ............................................................................................................ 14

6.1 General ................................................................................................................. 14

6.2 Preparation of the test objects .............................................................................. 14

6.2.1 General ......................................................................................................... 14

6.2.2 Reference test object ..................................................................................... 14

6.2.3 Candidate test object ..................................................................................... 15

6.3 Diagnostic tests .................................................................................................... 16

6.3.1 General ......................................................................................................... 16

6.3.2 Solid insulation .............................................................................................. 16

6.3.3 Liquid insulation ............................................................................................ 16

6.4 End-point testing ................................................................................................... 16

6.5 Simplified one-point test ....................................................................................... 17

7 Analysis of data ............................................................................................................. 17

7.1 End-point criteria .................................................................................................. 17

7.1.1 General ......................................................................................................... 17

7.1.2 End-of-life of the solid component.................................................................. 17

7.1.3 Extrapolation of data ...................................................................................... 17

7.2 Report................................................................................................................... 17

Annex A (informative) Consideration of weight ratios ........................................................... 19

A.1 Examples of transformers leading to actual weight ratios in Table A.1 .................. 19

A.2 Calculation of core steel surface ratios ................................................................. 19

A.3 Calculation of copper components of test .............................................................. 20

A.3.1 Wire enamel samples .................................................................................... 20

A.3.2 Bare copper samples ..................................................................................... 20

---------------------- Page: 4 ----------------------
IEC TS 62332-2:2014 © IEC 2014 – 3 –

Annex B (informative) Consideration of ageing time and temperature .................................. 21

Annex C (informative) Aging example .................................................................................. 22

C.1 Reference system test .......................................................................................... 22

C.2 Candidate system test .......................................................................................... 22

Bibliography .......................................................................................................................... 25

Figure 1 – Sealed tube example............................................................................................ 11

Figure B.1 – Reference EIS system ...................................................................................... 21

Figure C.1 – Example of aging result at a temperature of 165 °C .......................................... 23

Figure C.2 – Aging life curve ................................................................................................. 24

Table 1 – Reference component weight ratio calculations ..................................................... 12

Table 2 – Reference EIS ageing conditions and candidate EIS ageing temperatures ............ 15

Table 3 – Recommended ageing temperatures and periods for expected thermal class ........ 15

Table A.1 – Examples obtained from industry sources .......................................................... 19

Table A.2 – Examples of component volume ratio calculations .............................................. 19

Table C.1 – Calculation of end-of-life criteria for comparative evaluation .............................. 22

Table C.2 – Example of aging experiment ............................................................................. 23

---------------------- Page: 5 ----------------------
– 4 – IEC TS 62332-2:2014 © IEC 2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL INSULATION SYSTEMS (EIS) –
THERMAL EVALUATION OF COMBINED LIQUID
AND SOLID COMPONENTS –
Part 2: Simplified test
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

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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.

The main task of IEC technical committees is to prepare International Standards. In

exceptional circumstances, a technical committee may propose the publication of a technical

specification when

• the required support cannot be obtained for the publication of an International Standard,

despite repeated efforts, or

• the subject is still under technical development or where, for any other reason, there is the

future but no immediate possibility of an agreement on an International Standard.

Technical specifications are subject to review within three years of publication to decide

whether they can be transformed into International Standards.

IEC TS 62332-2, which is a technical specification, has been prepared by IEC technical

committee 112: Evaluation and qualification of electrical insulating materials and systems.

---------------------- Page: 6 ----------------------
IEC TS 62332-2:2014 © IEC 2014 – 5 –
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
112/256/DTS 112/268/RVC

Full information on the voting for the approval of this technical specification 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 the parts in the IEC 62332 series, published under the general title Electrical

insulation systems (EIS) – Thermal evaluation of combined liquid and solid components, 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 web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct

understanding of its contents. Users should therefore print this document using a

colour printer.
---------------------- Page: 7 ----------------------
– 6 – IEC TS 62332-2:2014 © IEC 2014
INTRODUCTION

This technical specification describes a method for the thermal evaluation of electrical

insulation systems (EIS) for electrotechnical products with combined liquid and solid

components. More specifically, this part addresses liquid immersed power transformers.

Part 1 covers general test requirements. This Part 2 covers a simplified test method which

can be used as a screening test prior to conducting Part 1 testing or it can be used to

determine a thermal classification of an EIS. This method can also be used as a quality

control test to evaluate minor product changes.

This specification provides a standardized test method for sealed tube testing. The sealed

tube should contain all the primary EIS elements, and in relative component ratios which

compare with actual liquid immersed power transformers.

This technical specification has been prepared in conjunction with IEC TC 14, Power

transformers and IEC TC 10, Fluids for electrotechnical applications. Any comments or

suggestions from other technical committees to make this technical specification more general

are welcome.
---------------------- Page: 8 ----------------------
IEC TS 62332-2:2014 © IEC 2014 – 7 –
ELECTRICAL INSULATION SYSTEMS (EIS) –
THERMAL EVALUATION OF COMBINED LIQUID
AND SOLID COMPONENTS –
Part 2: Simplified test
1 Scope

This part of IEC 62332, which is a technical specification, is applicable to EIS containing solid

and liquid components where the thermal stress is the dominant ageing factor, without

restriction to voltage class.

This part specifies a sealed tube test procedure for the thermal evaluation and qualification of

electrical insulation systems (EIS). One aspect of this procedure is to also provide a method

to assign thermal classifications to materials used in EIS where solid and liquid components

are both used. This procedure describes a comparative ageing method whereby a reference

system composed of kraft paper and mineral oil is compared to a candidate system of any

combination of solid and insulating liquid. The test procedures in this part are specifically

applicable to liquid immersed transformer insulation systems.

Similar procedures should also work for other electrotechnical devices with a combination of

liquid and solid components, such as bushings, cables or capacitors, but this will be added as

additional parts once experience is gained using this technical specification.
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 60085, Electrical insulation – Thermal evaluation and designation

IEC 60156, Insulating liquids – Determination of the breakdown voltage at power frequency –

Test method

IEC 60216-2:2005, Electrical insulating materials – Thermal endurance properties – Part 2:

Determination of thermal endurance properties of electrical insulating materials – Choice of

test criteria

IEC 60216-3, Electrical insulating materials – Thermal endurance properties – Part 3:

Instructions for calculating thermal endurance characteristics

IEC 60216-4-1, Electrical insulating materials – Thermal endurance properties – Part 4-1:

Ageing ovens – Single-chamber ovens

IEC 60216-5, Electrical insulating materials – Thermal endurance properties – Part 5:

Determination of relative thermal endurance index (RTE) of an insulating material

IEC 60243-1, Electrical strength of insulating materials – Test methods – Part 1: Tests at

power frequencies
---------------------- Page: 9 ----------------------
– 8 – IEC TS 62332-2:2014 © IEC 2014

IEC 60247, Insulating liquids – Measurement of relative permittivity, dielectric dissipation

factor (tan δ) and d.c. resistivity

IEC 60296, Fluids for electrotechnical applications – Unused mineral insulating oils for

transformers and switchgear
IEC 60317 (all parts), Specifications for particular types of winding wires

IEC 60450, Measurement of the average viscometric degree of polymerization of new and

aged cellulosic electrically insulating materials
IEC 60505:2011, Evaluation and qualification of electrical insulation systems
IEC 60554-2, Cellulosic papers for electrical purposes – Part 2: Methods of test

IEC 60567, Oil-filled electrical equipment – Sampling of gases and of oil for analysis of free

and dissolved gases – Guidance

IEC 60599, Mineral oil-impregnated electrical equipment in service – Guide to the

interpretation of dissolved and free gases analysis
IEC 60763-2, Specification for laminated pressboard – Part 2: Methods of test

IEC 60814, Insulating liquids – Oil-impregnated paper and pressboard – Determination of

water by automatic coulometric Karl Fischer titration
IEC 60851-5, Winding wires – Test methods – Part 5: Electrical properties

IEC 61198, Mineral insulating oils– Methods for the determination of 2-furfural and related

compounds

IEC 61620, Insulating liquids – Determination of dielectric dissipation factor by measurement

of the conductance and capacitance – Test method

IEC 62021-1, Insulating liquids – Determination of acidity – Part 1: Automatic potentiometric

titration

IEC 62021-2, Insulating liquids – Determination of acidity – Part 2: Colourimetric titration

IEC 62021-3, Insulating liquids – Determination of acidity – Part 3: Test methods for non

mineral insulating oils

IEC TS 62332-1:2011, Electrical insulation systems (EIS) – Thermal evaluation of combined

liquid and solid components – Part 1: General requirements
ISO 2049, Petroleum products – Determination of colour (ASTM scale)

ISO 2211, Liquid chemical products – Measurement of colour in Hazen units (platinum-cobalt

scale)

ASTM D971, Standard Test Method for Interfacial Tension Of Oil Against Water By The Ring

Method
---------------------- Page: 10 ----------------------
IEC TS 62332-2:2014 © IEC 2014 – 9 –
3 Terms and definitions

For the purposes of this document, the following terms and definitions apply, some of which

are taken from IEC 60505.
3.1
electrical insulation system
EIS

insulating structure containing one or more electrical insulating materials (EIM) together with

associated conducting parts employed in an electrotechnical device

Note 1 to entry: EIMs with different temperature indices (ATE RTE according to IEC 60216-5) may be combined to

form an EIS, which has a thermal class that may be higher or lower than that of any of the individual components

according to IEC 60505.
[SOURCE: IEC 60505:2011, 3.1.1 – modified, the Note 1 to entry has been added]
3.2
candidate EIS
EIS under evaluation to determine its service capability (thermal)
3.3
reference EIS

evaluated and established EIS with either a known service experience record or a known

comparative functional evaluation as a basis
3.4
thermal class

designation of an EIS that is equal to the numerical value of the maximum temperature in

degrees Celsius for which the EIS is appropriate according to IEC 60085

Note 1 to entry: An EIS may be subjected to operating temperatures exceeding its thermal class, which can result

in shorter expected life.
3.5
EIS assessed thermal endurance index
EIS ATE

numerical value of the temperature in degrees Celsius for the reference EIS as derived from

known service experience or a known comparative functional evaluation
3.6
EIS relative thermal endurance index
EIS RTE

numerical value of the temperature in degrees Celsius for the candidate EIS which is relative

to the known EIS ATE of a reference EIS when both EIS are subjected to the same ageing

and diagnostic procedures in a comparative test
3.7
test object

piece of original equipment, a representation (model) of equipment, a component of or part of

equipment, including the EIS, intended for use in a functional test
3.8
thermal ageing factor
thermal stress that causes irreversible changes in the EIS
---------------------- Page: 11 ----------------------
– 10 – IEC TS 62332-2:2014 © IEC 2014
3.9
diagnostic test

periodic application of a specified level of a diagnostic factor to a test object to determine

whether the end-point criterion has been reached
3.10
end-point criterion

selected value of either a property or a change of property that defines the end of a

component’s life

[SOURCE: IEC 61857-1:2008, 3.11, modified – "component's life" replaces "test object in a

functional test]
3.11
end-of-life

end of a test object’s life, as determined by any selected component meeting its end-point

criterion
3.12
sealed tube

sealed container partially filled with the liquid EIM and in which includes the solid EIM in

relative component ratios which compare with the actual electrotechnical device
3.13
halving value
HIC

numerical value of the temperature interval in Kelvins which expresses the halving of the time

to end-point taken at the temperature equal to TI

[SOURCE: IEC 60050-212:2010, 212-12-13, modified – "equal to TI" replaces the original

"corresponding to the temperature index or the relative temperature index"]
4 Thermal ageing test apparatus
4.1 General description

The thermal ageing test apparatus shall be designed to allow the ageing of solid and liquid

components. The reference and candidate EIS shall be exposed to test periods at selected

elevated temperatures. These test periods consist of a specific time exposure at the selected

temperature followed by diagnostic tests. The test system consists of the following elements:

• sealed tubes
• ageing ovens
• test objects.
4.2 Sealed tubes
Each sealed tube is a container constructed of stainless steel or other s
...

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