Dielectric and resistive properties of solid insulating materials - Part 2-1: Relative permittivity and dissipation factor - Technical Frequencies (0.1 Hz - 10 MHz), AC Methods (IEC 62631-2-1:2018)

This part of IEC 62631 describes test methods for the determination of permittivity and
dissipation factor properties of solid insulating materials (AC methods from 0,1 Hz up to
10 MHz).
NOTE This part of the standard mainly considers measuring setups with guard-electrodes.

Dielektrische und resistive Eigenschaften fester Elektroisolierstoffe - Teil 2-1: Relative Permittivität und Verlustfaktor - Technische Frequenzen (0,1 Hz bis 10 MHz) – Wechselspannungsverfahren

Propriétés diélectriques et résistives des matériaux isolants solides - Partie 2-1: Permittivité relative et facteur de dissipation - Fréquences techniques (0,1 Hz à 10 MHz), méthodes en courant alternatif (IEC 62631-2-1:2018)

L'IEC 62631-2-1:2018 décrit des méthodes d'essai pour déterminer les propriétés de la permittivité et du facteur de dissipation de matériaux isolants solides (méthodes en courant alternatif de 0,1 Hz à 10 MHz). Cette première édition annule et remplace la première édition de l'IEC 60250, publiée en 1969. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: a. fréquences techniques réservées aux méthodes en courant alternatif; b. mise à jour des mesures appliquées aux matériaux diélectriques solides.

Dielektrične in uporovne lastnosti trdnih izolacijskih materialov - 2-1. del: Relativna permitivnost in faktor izgube - Tehnične frekvence (0,1 Hz – 10 MHz), metode AC (IEC 62631-2-1:2018)

Ta del standarda IEC 62631 opisuje preskusne metode za določitev lastnosti permitivnosti in faktorja izgube trdnih izolacijskih materialov (AC metode od 0,1 Hz in 10 MHz.
OPOMBA Ta del standarda v glavnem obravnava načine merjenja z varovalnimi elektrodami.

General Information

Status
Published
Publication Date
14-May-2018
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
25-Apr-2018
Due Date
30-Jun-2018
Completion Date
15-May-2018

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SLOVENSKI STANDARD
SIST EN IEC 62631-2-1:2018
01-julij-2018
'LHOHNWULþQHLQXSRURYQHODVWQRVWLWUGQLKL]RODFLMVNLKPDWHULDORYGHO
5HODWLYQDSHUPLWLYQRVWLQIDNWRUL]JXEH7HKQLþQHIUHNYHQFH +]±0+] 
PHWRGH$& ,(&

Dielectric and resistive properties of solid insulating materials - Part 2-1: Relative

permittivity and dissipation factor - Technical Frequencies (0.1 Hz - 10 MHz), AC

Methods (IEC 62631-2-1:2018)

Propriétés diélectriques et résistives des matériaux isolants solides - Partie 2-1:

Permittivité relative et facteur de dissipation - Fréquences techniques (0,1 Hz à 10 MHz),

méthodes en courant alternatif (IEC 62631-2-1:2018)
Ta slovenski standard je istoveten z: EN IEC 62631-2-1:2018
ICS:
29.035.01 Izolacijski materiali na Insulating materials in
splošno general
SIST EN IEC 62631-2-1:2018 en

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

---------------------- Page: 1 ----------------------
SIST EN IEC 62631-2-1:2018
---------------------- Page: 2 ----------------------
SIST EN IEC 62631-2-1:2018
EUROPEAN STANDARD EN IEC 62631-2-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2018
ICS 17.220.99; 29.035.01
English Version
Dielectric and resistive properties of solid insulating materials -
Part 2-1: Relative permittivity and dissipation factor - Technical
frequencies (0,1 Hz to 10 MHz) - AC Methods
(IEC 62631-2-1:2018)

Propriétés diélectriques et résistives des matériaux isolants Dielektrische und resistive Eigenschaften fester

solides - Partie 2-1: Permittivité relative et facteur de Elektroisolierstoffe Teil 2-1: Dielektrizitätszahl und der

dissipation - Fréquences techniques (0,1 Hz à 10 MHz) - Verlustfaktor Technische Frequenzen (0,1 Hz - 10 MHz) -

Méthodes en courant alternatif Wechselspannungsverfahren
(IEC 62631-2-1:2018) (IEC 62631-2-1:2018)

This European Standard was approved by CENELEC on 2018-04-03. CENELEC members are bound to comply with the CEN/CENELEC

Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC

Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,

Switzerland, Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2018 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN IEC 62631-2-1:2018 E
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SIST EN IEC 62631-2-1:2018
EN IEC 62631-2-1:2018 (E)
European foreword

The text of document 112/412/FDIS, future edition 1 of IEC 62631-2-1, prepared by IEC/TC 112

"Evaluation and qualification of electrical insulating materials and systems" was submitted to the IEC-

CENELEC parallel vote and approved by CENELEC as EN IEC 62631-2-1:2018.
The following dates are fixed:
• latest date by which the document has to be (dop) 2019-01-03
implemented at national level by
publication of an identical national
standard or by endorsement
(dow) 2021-04-03
• latest date by which the national
standards conflicting with the
document have to be withdrawn

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Endorsement notice

The text of the International Standard IEC 62631-2-1:2018 was approved by CENELEC as a

European Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standards indicated:

IEC 60216-1 NOTE Harmonized as EN 60216-1.
IEC 60216-4-1:2006 NOTE Harmonized as EN 60216-4-1:2006 (not modified).
IEC 60247 NOTE Harmonized as EN 60247.
IEC 60505 NOTE Harmonized as EN 60505.
IEC 62631-1 NOTE Harmonized as EN 62631-1.
IEC 60455 series NOTE Harmonized as EN 60455 series.
IEC 60464 series NOTE Harmonized as EN 60464 series.
IEC 61212 series NOTE Harmonized as EN 61212 series.
ISO 291 NOTE Harmonized as EN ISO 291.
ISO 294-1 NOTE Harmonized as EN ISO 294-1.
ISO 294-3 NOTE Harmonized as EN ISO 294-3.
ISO 295 NOTE Harmonized as EN ISO 295.
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SIST EN IEC 62631-2-1:2018
EN IEC 62631-2-1:2018 (E)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments)

applies.

NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the relevant

EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:

www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60212 - Standard conditions for use prior to and EN 60212 -
during the testing of solid electrical
insulating materials
ISO 4593 - Plastics - Film and sheeting - - -
Determination of thickness by mechanical
scanning
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SIST EN IEC 62631-2-1:2018
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SIST EN IEC 62631-2-1:2018
IEC 62631-2-1
Edition 1.0 2018-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Dielectric and resistive properties of solid insulating materials –
Part 2-1: Relative permittivity and dissipation factor – Technical frequencies
(0,1 Hz to 10 MHz) – AC methods
Propriétés diélectriques et résistives des matériaux isolants solides –

Partie 2-1: Permittivité relative et facteur de dissipation – Fréquences techniques

(0,1 Hz à 10 MHz) – Méthodes en courant alternatif
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.99; 29.035.01 ISBN 978-2-8322-5414-1

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: 7 ----------------------
SIST EN IEC 62631-2-1:2018
– 2 – IEC 62631-2-1:2018 © IEC 2018
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions ...................................................................................................... 6

4 Method of test ................................................................................................................. 7

4.1 General theory ........................................................................................................ 7

4.2 Power supply (voltage) ......................................................................................... 10

4.3 Equipment ............................................................................................................ 10

4.3.1 Accuracy ....................................................................................................... 10

4.3.2 Choice of measuring methods ........................................................................ 10

4.3.3 Measurement setup with applied electrodes to the material ........................... 11

4.4 Calibration ............................................................................................................ 14

4.5 Test specimen ...................................................................................................... 14

4.5.1 General ......................................................................................................... 14

4.5.2 Recommended dimensions of test specimen and electrode

arrangements ................................................................................................ 15

4.5.3 Manufacturing of test specimen ..................................................................... 15

4.5.4 Number of test specimen ............................................................................... 15

4.5.5 Conditioning and pre-treatment of test specimen ........................................... 16

4.6 Procedures for specific materials .......................................................................... 16

5 Test procedure .............................................................................................................. 16

5.1 General ................................................................................................................. 16

5.2 Calculation of permittivity and relative permittivity ................................................. 16

5.2.1 Relative permittivity ....................................................................................... 16

5.2.2 The dielectric dissipation factor tan δ ............................................................. 16

6 Report ........................................................................................................................... 16

7 Repeatability and reproducibility .................................................................................... 17

Annex A (informative) Basic fundamentals ........................................................................... 18

A.1 Error for the effective area in guard ring electrodes – Examples with d =

25 mm, 50 mm or 100 mm and w = 1 mm .............................................................. 18

A.2 Computation of edge correction of effective area .................................................. 19

A.3 Determining H and calculating B ........................................................................... 20

Bibliography .......................................................................................................................... 21

Figure 1 – Dielectric dissipation factor .................................................................................... 8

Figure 2 – Equivalent circuit diagrams .................................................................................... 9

Figure 3 – Cylindrical electrode with guard ring for plate designed specimen ........................ 12

Figure 4 – Specimen with liquid electrodes ........................................................................... 13

Figure A.1 – Area error of h in e with Ɛ = 1 ........................................................................ 18

% r

Figure A.2 – Area error of h in e with Ɛ = ∞ ....................................................................... 18

% r

Figure A.3 – Error calculation for different Ɛ and d ............................................................. 18

r 1

Figure A.4 – Flow chart for the computation of edge correction of effective area ................... 19

Figure A.5 – Factor H versus gap and height ........................................................................ 20

Table 1 – Test specimen ....................................................................................................... 15

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SIST EN IEC 62631-2-1:2018
IEC 62631-2-1:2018 © IEC 2018 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DIELECTRIC AND RESISTIVE PROPERTIES
OF SOLID INSULATING MATERIALS –
Part 2-1: Relative permittivity and dissipation factor –
Technical frequencies (0,1 Hz to 10 MHz) – AC methods
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 62631-2-1 has been prepared by IEC technical committee 112:

Evaluation and qualification of electrical insulating materials and systems.

This first edition cancels and replaces the first edition IEC 60250, published in 1969. This

edition constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) technical frequencies confined to AC methods;
b) update on measurements on solid dielectric materials.
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SIST EN IEC 62631-2-1:2018
– 4 – IEC 62631-2-1:2018 © IEC 2018
The text of this standard is based on the following documents:
FDIS Report on voting
112/412/FDIS 112/417/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.

A list of all parts in the IEC 62631 series, published under the general title Dielectric and

resistive properties of solid insulating materials, 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.

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.
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SIST EN IEC 62631-2-1:2018
IEC 62631-2-1:2018 © IEC 2018 – 5 –
INTRODUCTION

Tan δ, also called loss tangent, or dissipation factor is a basic parameter for the quality of

insulating materials. The measurement of capacitance and loss angle is a classical method

well established in the industry over 100 years.

The dissipation factor (tan δ) is dependent on several parameters, such as electrode design,

material characteristics, environmental issues, moisture, temperature, voltage applied, and

highly dependent on frequencies, the accuracy of measuring apparatus and other parameters

applied to the measured specimen.

The frequency range is limited, depending on the test cell and electrode design, the

dimension of the samples and connection leads. In this standard the parameters for the

frequencies applied are therefore limited in the range of very low frequency (VLF) from less

than 1 Hz and up to 10 MHz. However, measuring instruments can provide a broader

frequency range, whereby the usable and suitable frequency range is limited by the whole test

setup.
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SIST EN IEC 62631-2-1:2018
– 6 – IEC 62631-2-1:2018 © IEC 2018
DIELECTRIC AND RESISTIVE PROPERTIES
OF SOLID INSULATING MATERIALS –
Part 2-1: Relative permittivity and dissipation factor –
Technical frequencies (0,1 Hz to 10 MHz) – AC methods
1 Scope

This part of IEC 62631 describes test methods for the determination of permittivity and

dissipation factor properties of solid insulating materials (AC methods from 0,1 Hz up to

10 MHz).

NOTE This part of the standard mainly considers measuring setups with guard-electrodes.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their

content constitutes requirements of this document. For dated references, only the edition

cited applies. For undated references, the latest edition of the referenced document (including

any amendments) applies.

IEC 60212, Standard conditions for use prior to and during the testing of solid electrical

insulating materials

ISO 4593, Plastics – Film and sheeting – Determination of thickness by mechanical scanning

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
electrical insulating material

solid with negligibly low electric conductivity, used to separate conducting parts at different

electrical potentials

Note 1 to entry: The term "electrical insulating material" is sometimes used in a broader sense to designate also

insulating liquids and gases. Insulating liquids are covered by IEC 60247.
3.2
dielectric properties

comprehensive behaviour of an insulating material measured with AC comprising the

capacitance, absolute permittivity, relative permittivity, relative complex permittivity, dielectric

dissipation factor
3.3
absolute permittivity
electric flux density divided by the electric field strength
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SIST EN IEC 62631-2-1:2018
IEC 62631-2-1:2018 © IEC 2018 – 7 –
3.4
relative permittivity
ratio of the absolute permittivity to the permittivity of a vacuum ε
3.5
relative complex permittivity

permittivity in a complex number representation, under steady sinusoidal field conditions

3.6
dielectric dissipation factor tan δ (loss tangent)

numerical value of the ratio of the imaginary to the real part of the complex permittivity

3.7
capacitance C

property of an arrangement of conductors and dielectrics which permits the storage of

electrical charge when a potential difference exists between the conductors
3.8
voltage application
application of a voltage between electrodes

Note 1 to entry: Voltage application is sometimes referred to as electrification.

3.9
measuring electrodes

conductors applied to, or embedded in, a material to make contact with it to measure its

dielectric or resistive properties

Note 1 to entry: The design of the measuring electrodes depends on the specimen and the purpose of the test.

4 Method of test
4.1 General theory

The measured permittivity (formerly known as dielectric constant) ε of an insulating material is

the product of its relative permittivity ε and the permittivity of a vacuum ε :
r 0
ε=ε ⋅ε (1)
0 r

The permittivity is expressed in farad per meter (F/m); the permittivity of vacuum ε has the

following value:
−12
ε = 8,854187817⋅10 (2)

Relative permittivity is the ratio of the absolute permittivity to the permittivity of a vacuum ε .

In the case of constant fields and alternating fields of sufficiently low frequency the relative

permittivity of an isotropic or quasi-isotropic dielectric is equal to the ratio of the capacitance

of a capacitor, in which the space between and around the electrodes is entirely and

exclusively filled with the dielectric, to the capacitance of the same configuration of electrodes

in vacuum.
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SIST EN IEC 62631-2-1:2018
– 8 – IEC 62631-2-1:2018 © IEC 2018

In practical engineering it is usual to employ the term permittivity when referring to relative

permittivity. The relative permittivity ε of an insulating material is the quotient of capacitance

C of a capacitive test specimen (capacitor), in which the space between the two electrodes is

entirely and exclusively filled with the insulating material in question, and the capacitance C

of the same configuration of electrodes in vacuum:
ε = (3)

The relative permittivity ε of dry air free from carbon dioxide, at normal atmospheric pressure

in Pa, equals 100053 Pa, so that in practice, the capacitances C of the configuration of

electrodes in air can normally be used instead of C to determine the relative permittivity ε

0 r
with sufficient accuracy.

Relative complex permittivity is permittivity in a complex number representation under steady

sinusoidal field conditions expressed as
' " − jδ
ε =ε − jε =⋅ε ⋅ e (4)
r r r
where ε' and ε'' have positive values.
r r

NOTE 1 The complex permittivity is customarily quoted either in terms of ε' and ε'' , or in terms of ε

r r r
and tan δ. If ε' > ε'' then ε ≈ ε' which are both called relative permittivity.
r r r r
NOTE 2 ε'' is termed loss index.
I U
IEC
Figure 1 – Dielectric dissipation factor

The dielectric dissipation factor tan δ (loss tangent) is the numerical value of the ratio of the

imaginary to the real part of the complex permittivity.
tanδ= (5)
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SIST EN IEC 62631-2-1:2018
IEC 62631-2-1:2018 © IEC 2018 – 9 –
R C
s s
IEC
Figure 2 – Equivalent circuit diagrams

Thus, the dielectric dissipation factor tan δ of an insulating material is the tangent of the

angle δ by which the phase difference ϕ between the applied voltage and the resulting current

deviates from π/2 rad when the solid insulating material is exclusively used as dielectric in a

capacitive test specimen (capacitor) (compare with Figure 1). The dielectric dissipation factor

can also be expressed by an equivalent circuit diagram using an ideal capacitor with a

resistor in series or parallel connection (see Figure 2).
(6)
tanδ=ωC ⋅ R =
s s
ωC ⋅ R
p p
with
p 1
= (7)
s 1+ tan δ
and
p 1
= 1+ (8)
tan δ

NOTE 3 R and R respectively are not directly related to but affected by the volume and the surface resistance of

S P

an insulating material. Therefore the dielectric dissipation factor may also be affected by these resistive materials

properties.

Capacitance C is the property of an arrangement of conductors and dielectrics which permits

the storage of electrical charge when a potential difference exists between the conductors.

C is the ratio of a quantity q of charge to a potential difference U. A capacitance value is

always positive. The unit is farad when the charge is expressed in coulomb and the potential

in volts.
C= (9)

This general method describes common values for general measurements. If a method for a

specific type of material is described in this standard, the specific method shall be used.

The measurement of permittivity and dielectric dissipation factor is to be done carefully and

under consideration of the electric properties of the measuring circuit as well as the specific

electric properties of the material.
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– 10 – IEC 62631-2-1:2018 © IEC 2018

NOTE 4 To carry out the test, in most cases the use of high voltage is necessary. Care shall be taken to prevent

from electric shock.

The basic principles of apparatus and methods are not described here. Some references to

the literature is given in the bibliography.
4.2 Power supply (voltage)

The power source shall provide a stable sinusoidal voltage. For the measuring duration the

measured value of the supplied voltage shall be maintained within ± 5 %.

The voltage wave shape shall approximate to a sinusoid with the difference of the magnitudes

of the positive and negative peak values being less than 2 %.

The deviation of the sinusoidal shape (the ratio of peak to r.m.s. values equals 2 ) shall be

within ± 5 %.
Preferred voltages are 0,1 V; 0,5 V; 10 V; 100 V; 500 V; 1 000 V; 2 000 V.

Higher voltages may be applicable in order to perform tests at operating field strength. Other

voltage levels shall be documented in the report.

NOTE Partial discharge can lead to erroneous measurements when a specific inception voltage is exceeded. In

air, below 340 V no partial discharges will occur.
4.3 Equipment
4.3.1 Accuracy

The measuring device should be capable of determining the unknown permittivity and

dielectric dissipation factor in accordance with the expected material properties. The accuracy

of the measuring system must be documented in the report.

NOTE The user can choose the measuring system accuracy according to the requirements of the measuring

results.
4.3.2 Choice of measuring methods
4.3.2.1 General

Methods for measuring the permittivity and dissipation factor can be divided into three groups:

• null method
• impedance analyser method
• digital phase shift method
4.3.2.2 Null method

For measurements of permittivity and dissipation factor, substitution techniques can be used

that is, the bridge is balanced by adjustment mainly in one arm of the network, with and

without the specimen connected. The networks normally used are the Schering bridge, the

transformer bridge (i.e. a bridge with ratio arms coupled by mutual inductance) and the

parallel-T. The transformer bridge has the advantage of allowing the use of a guard electrode

without any additional components or operations; it has no disadvantages in comparison with

the other networks.
4.3.2.3 Impedance analyser method

There exist a lot of commercially available instruments (impedance analyzers or LCR meters).

These instruments determine the impedance of the specimen as the ratio of the measured

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SIST EN IEC 62631-2-1:2018
IEC 62631-2-1:2018 ©
...

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