SIST EN 60247:2004

SLOVENSKI SIST EN 60247:2004

STANDARD
september 2004
Izolirne tekočine - Merjenje relativne dielektrične konstante, faktor dielektrične
izgube (tangens ) in enosmerne upornosti (IEC 60247:2004)
Insulating liquids - Measurement of relative permittivity, dielectric dissipation factor
(tan ) and dc resistivity (IEC 60247:2004)
ICS 29.040.01 Referenčna številka
SIST EN 60247:2004(en)
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

---------------------- Page: 1 ----------------------

EUROPEAN STANDARD EN 60247
NORME EUROPÉENNE
EUROPÄISCHE NORM April 2004

ICS 17.220.99; 29.040.10


English version


Insulating liquids –
Measurement of relative permittivity,
dielectric dissipation factor (tan δ) and d.c. resistivity
(IEC 60247:2004)


Liquides isolants –  Isolierflüssigkeiten –
Mesure de la permittivité relative, Messung der Permittivitätszahl,
du facteur de dissipation diélectrique
des dielektrischen Verlustfaktors (tan δ)
(tan δ) et de la résistivité en courant und des spezifischen Gleichstrom-
continu Widerstandes
(CEI 60247:2004) (IEC 60247:2004)






This European Standard was approved by CENELEC on 2004-04-01. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden,
Switzerland and United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels


© 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 60247:2004 E

---------------------- Page: 2 ----------------------

EN 60247:2004 - 2 -
Foreword
The text of document 10/573/FDIS, future edition 3 of IEC 60247, prepared by IEC TC 10, Fluids for
electrotechnical applications, was submitted to the IEC-CENELEC parallel vote and was approved by
CENELEC as EN 60247 on 2004-04-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2005-01-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2007-04-01
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60247:2004 was approved by CENELEC as a European
Standard without any modification.
__________

---------------------- Page: 3 ----------------------

- 3 - EN 60247:2004
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications
The following referenced documents are indispensable for the application 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 Where an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
1) 2)
IEC 60093 - Methods of test for volume resistivity and HD 429 S1 1983
surface resistivity of solid electrical
insulating materials

1)
IEC 60250 - Recommended methods for the - -
determination of the permittivity and
dielectric dissipation factor of electrical
insulating materials at power, audio and
radio frequencies including metre
wavelengths

1)
IEC 60475 - Method of sampling liquid dielectrics - -

1) 2)
IEC 61620 - Insulating liquids - Determination of the EN 61620 1999
dielectric dissipation factor by
measurement of the conductance and
capacitance - Test method





1)
Undated reference.
2)
Valid edition at date of issue.

---------------------- Page: 4 ----------------------

NORME
CEI
INTERNATIONALE IEC
60247
INTERNATIONAL
Troisième édition
STANDARD
Third edition
2004-02
Liquides isolants –
Mesure de la permittivité relative,
du facteur de dissipation diélectrique (tan δδδδ)
et de la résistivité en courant continu
Insulating liquids –
Measurement of relative permittivity,
dielectric dissipation factor (tan δδ)
δδ
and d.c. resistivity
© IEC 2004 Droits de reproduction réservés ⎯ Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized in any
utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including
électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from
microfilms, sans l'accord écrit de l'éditeur. the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch  Web: www.iec.ch
CODE PRIX
U
Commission Electrotechnique Internationale PRICE CODE
International Electrotechnical Commission
ɆɟɠɞɭɧɚɪɨɞɧɚɹɗɥɟɤɬɪɨɬɟɯɧɢɱɟɫɤɚɹɄɨɦɢɫɫɢɹ
Pour prix, voir catalogue en vigueur
For price, see current catalogue

---------------------- Page: 5 ----------------------

60247 © IEC:2004 – 3 –
CONTENTS
FOREWORD.7
INTRODUCTION.11
1 Scope.13
2 Normative references.13
3 Terms and definitions .13
4 General .15
4.1 Permittivity and dielectric dissipation factor (tan δ) .15
4.2 Resistivity.17
4.3 Sequence of determinations.17
4.4 Factors leading to erroneous results .17
5 Apparatus.19
5.1 Test cell .19
5.2 Test equipment.21
5.3 Glassware .21
5.4 Measuring instrument for permittivity and tan δ.21
5.5 Measuring instrument for d.c. resistivity .21
5.6 Time-measuring device.21
5.7 Safety.21
6 Cleaning solvent .23
7 Cleaning the test cell .23
7.1 Trisodium phosphate cleaning procedure .23
7.2 Storage of cell .25
8 Sampling .25
9 Preparation of samples .25
10 Conditioning and filling the test cell .27
10.1 Cell conditioning .27
10.2 Filling the cell .27
11 Test temperature .27
12 Measurement of dissipation factor (tan δ).29
12.1 Test voltage.29
12.2 Measurement .29
12.3 Report .29
13 Measurement of relative permittivity.29
13.1 Measurement .29
13.2 Report .31
14 Measurement of d.c. resistivity.31
14.1 Test voltage.31
14.2 Time of electrification .31
14.3 Measurement .31
14.4 Report .33

---------------------- Page: 6 ----------------------

60247 © IEC:2004 – 5 –
Annex A (informative) Example of an alternative procedure for cleaning the test cell –
Ultrasonic procedure .35
Annex B (informative) Example of a simplified cleaning procedure for a test cell .37
Annex C (informative) Alternative procedures for routine testing of dielectric dissipation
factor and resistivity of insulating liquids.39
Figure 1 – Example of a three-terminal cell for measurements on liquids .45
Figure 2 – Example of screening for the cell of Figure 1.47
Figure 3 – Example of assembling drawing of cell.49
Figure 4 – Example of a two-terminal cell for measurements in liquids .51
Figure 5 – Example of a test cell designed for low-loss dielectric liquids .53

---------------------- Page: 7 ----------------------

60247 © IEC:2004 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
INSULATING LIQUIDS –
MEASUREMENT OF RELATIVE PERMITTIVITY,
DIELECTRIC DISSIPATION FACTOR (TAN δδδδ)
AND DC RESISTIVITY
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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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 60247 has been prepared by IEC technical committee 10: Fluids for
electrotechnical applications.
This third edition cancels and replaces the second edition published in 1978. This edition
constitutes a technical revision.
The main changes deal with the preferred measurement method.

---------------------- Page: 8 ----------------------

60247 © IEC:2004 – 9 –
The text of this standard is based on the following documents:
FDIS Report on voting
10/573/FDIS 10/575/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.
The committee has decided that the contents of this publication will remain unchanged until
2015. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.

---------------------- Page: 9 ----------------------

60247 © IEC:2004 – 11 –
INTRODUCTION
Health and safety
General caution. This International standard does not purport to address all the safety
problems associated with its use. It is the responsibility of the user of the standard to establish
appropriate health and safety practices and determine the applicability of regulatory limitations
prior to use.
Environment
This standard gives rise to insulating liquids, chemicals, used sample containers and oil
contaminated solids. The disposal of these items should be carried out according to local
regulations with regard to their impact on the environment. Every precaution should be taken to
prevent the release into the environment of these liquids.

---------------------- Page: 10 ----------------------

60247 © IEC:2004 – 13 –
INSULATING LIQUIDS –
MEASUREMENT OF RELATIVE PERMITTIVITY,
DIELECTRIC DISSIPATION FACTOR (TAN δδ)
δδ
AND DC RESISTIVITY
1 Scope
This International standard describes methods for the determination of the dielectric dissipation
factor (tan δ), relative permittivity and d.c. resistivity of any insulating liquid material at the test
temperature.
The methods are primarily intended for making reference tests on unused liquids. They can
also be applied to liquids in service in transformers, cables and other electrical apparatus.
However the method is applicable to a single phase liquid only. When it is desired to make
routine determinations, simplified procedures, as described in Annex C, may be adopted.
With insulating liquids other than hydrocarbons, alternative cleaning procedures may be
required.
2 Normative references
The following referenced documents are indispensable for the application 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 60093, Methods of test for volume resistivity and surface resistivity of solid electrical
insulating materials
IEC 60250, Recommended methods for the determination of the permittivity and dielectric
dissipation factor of electrical insulating materials at power, audio and radio frequencies
including metre wavelengths
IEC 60475, Method of sampling liquid dielectrics
IEC 61620, Insulating liquids – Determination of the dielectric dissipation factor by measure-
ment of the conductance and capacitance – Test method
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
permittivity (relative)
the relative permittivity of an insulating material is the ratio of capacitance C of a capacitor in
x
which the space between and around the electrodes is entirely and exclusively filled with the
insulating material in question, to the capacitance C of the same configuration of electrodes in
o
vacuum.
The capacitance C of the configuration of electrodes in air can normally be used instead of C
a o
to determine the relative permittivity with sufficient accuracy

---------------------- Page: 11 ----------------------

60247 © IEC:2004 – 15 –
3.2
dielectric dissipation factor (tan δδδδ)
DDF
dielectric dissipation factor, DDF, (tan δ) of an insulating material is the tangent of the loss
angle.
The loss angle is the angle by which the phase difference between applied voltage and the
resulting current deviates from π/2 rad when the dielectric of the capacitor consists exclusively
of the insulating material
NOTE For practical purposes, measured values below 0,005 for tan δ and power factor are essentially the same.
A simple conversion can be used to convert one to the other. The power factor is the sine of the loss angle and the
relationship between power factor and dielectric dissipation factor can be expressed as follows:
DDF
PF = (1)
2
1+ (DDF)
3.3
d.c. resistivity (volume)
the volume resistivity of an insulating material is the quotient of a d.c. electrical field strength
and the steady state current density within the material
NOTE The unit of resistivity is the ohmmetre (Ωm).
4 General
Permittivity, tan δ and resistivity, either separately or together, are important indicators of the
intrinsic quality and degree of contamination of an insulating fluid. These parameters may be
used to interpret the deviation from desired dielectric characteristics and the potential influence
on performance of equipment in which the fluid is used.
4.1 Permittivity and dielectric dissipation factor (tan δδδδ)
The permittivity and the dielectric dissipation factor (tan δ) of electrical insulating liquids
depend to a considerable extent on the test conditions under which they are measured, in
particular on the temperature and on the frequency of the applied voltage. Permittivity and
dissipation factor are the measurements of dielectric polarization and conductivity of the
material.
At power frequency and sufficiently high temperature, as recommended in these methods, the
losses may be attributable exclusively to the conductivity of the liquid, that is, to the presence
of free charge carriers in the liquid. Measurements of the dielectric properties of high purity
insulating liquids are therefore of value as an indication of the presence of contaminants.
The dielectric loss factor is usually inversely proportional to the measuring frequency and
varies with the viscosity of the medium. The value of the test voltage when measuring the
dissipation factor is less important and often governed by the sensitivity of the measuring
bridge. However, it must be borne in mind that too high a voltage stress results in secondary
phenomena at the electrodes, dielectric heating, discharges etc.
While relatively large amounts of impurities produce a comparatively small change in
permittivity, the tan δ of insulating liquids may be strongly affected by traces of dissolved
contaminants or colloidal particles. Some liquids are much more sensitive to contamination
than hydrocarbon liquids due to their higher polarity, which results in turn in higher solvent
power and dissociation capability. Therefore, they require comparatively greater care in
handling than hydrocarbon liquids.

---------------------- Page: 12 ----------------------

60247 © IEC:2004 – 17 –
Since the initial value is thought to be representative of the actual conditions of the liquid, it
appears most desirable that tan δ should be measured as soon as temperature equilibrium has
been reached. Tan δ is very sensitive to changes of temperature. Its increase, with increases in
temperature is generally exponential. It is therefore, necessary to carry out measurements,
under sufficiently precise temperature conditions. The procedure described below allows the
test specimen to attain temperature equilibrium with the test cell in minimum time.
4.2 Resistivity
The conventional resistivity as measured by this standard is generally not the true resistivity.
Application of a d.c. voltage will change the initial characteristics of the liquid with time, due to
charge migration. The true resistivity can only be obtained at low voltage, immediately after
application of the voltage. This standard uses a relatively high voltage for an extended time
and the result will generally be different from that from IEC 61620.
Measurements of resistivity of liquids to this standard, depends on a number of test conditions,
namely:
a) Temperature
Resistivity is very sensitive to changes of temperature, its dependence on the inverse of the
temperature, expressed in Kelvin, (1/K) is generally exponential. It is therefore necessary to
carry out measurements under sufficiently precise temperature conditions.
b) Magnitude of the electrical field
The resistivity of a given specimen may be influenced by the applied stress. For results to
be comparable, measurements shall be made with approximately equal voltage gradients
and with the same polarity. The gradients and the polarity shall be noted.
c) Time of electrification
Upon the application of d.c. voltage, the current flow through the specimen decreases due
to the sweep of charge carriers to the electrodes. The conventional arbitrary time of
electrification is 1 min. Variation in the time of electrification can result in appreciable
variation in the test results. (Some high viscosity fluids may require considerably longer
electrification time (see 14.2).)
4.3 Sequence of determinations
Application of d.c. voltage to a specimen can modify the results of a subsequent a.c.
determination of tan δ.
When permittivity, tan δ and resistivity measurements have to be made consecutively on the
same specimen, the a.c. determination shall always be made before applying the d.c. voltage
to the specimen. The cell electrodes should be short-circuited for a minimum of 1 min after the
a.c. tests, before beginning the resistivity measurements.
4.4 Factors leading to erroneous results
Only gross contamination is likely to affect permittivity. However, DDF and resistivity can be
strongly affected by minute amounts of contamination.
Unreliable results usually originate from contamination due to improper sampling or handling of
liquid specimens, from incomplete cleaning of the cells or from the absorption of water, and
especially from the presence of undissolved water.

---------------------- Page: 13 ----------------------

60247 © IEC:2004 – 19 –
Extended exposure to light during storage may lead to deterioration of dielectric character-
istics. Standardized procedures for the storage and transfer of the liquid samples and for the
construction and cleaning of test cells are recommended so that errors caused by contami-
nation are minimized.
5 Apparatus
5.1 Test cell
The same test cell can be used for measurements of permittivity, tan δ and d.c. resistivity.
A cell suitable for these purposes shall meet the following general requirements.
5.1.1 The design of the cell shall be such as to allow easy dismantling for cleaning of all its
parts and reassembling without significantly changing the capacitance of the empty cell. The
design shall also permit the use of the cell at the required constant temperature and shall
provide means to measure and control the temperature of the liquid to the required accuracy.
This may be achieved by means of an externally heated oven/bath or alternatively by internal
electrical heating of the cell.
5.1.2 The materials used in constructing the cell shall be non-porous and capable of
withstanding the required temperature satisfactorily. The alignment of the electrodes shall not
be influenced by change of temperature.
5.1.3 The surfaces of the electrodes in contact with the liquid under test shall have a smooth
finish to make their cleaning easier. There should be no chemical interactions between the
liquids under test and the electrodes. These should also be unaffected by the cleaning
materials. Cells made of stainless steel have been found satisfactory for testing all types of
insulating liquids. Aluminium or its alloys should not be used because they may be attacked by
alkaline detergents.
NOTE Generally, plated surfaces have been found less satisfactory than solid metal electrodes. However,
surfaces plated with gold, nickel or rhodium have been found satisfactory provided they are well plated and remain
undamaged. Rhodium-plated invar has been found satisfactory and has the additional advantage of low thermal
expansion. Nickel or gold-plated brass and nickel-plated stainless steel have also been used.
5.1.4 Solid insulating materials used to support the electrodes shall have a low tan δ and a
high resistivity. They should not absorb, or be adversely affected by, reference liquids, test
liquids or cleaning materials.
NOTE Fused silica is generally considered to be a suitable material for use as an insulating material in the cell. As
a consequence of the difference between the coefficients of linear expansion of usual metals and of fused silica, a
sufficient radial clearance is necessary between the joints. This clearance may decrease the accuracy of electrode
gap spacing.
5.1.5 The distance across the surface of the liquid and across the solid insulating material,
between the guard electrode and the measuring electrode, shall be great enough to withstand
the test voltage used.
5.1.6 Any cell which meets the requirements given in 5.1.1 to 5.1.5 may be used. Examples of
cells (not exclusive or exhaustive) which may be used with low viscosity liquids and up to
2 000 V are shown diagrammatically in Figures 1 to 5.
In the three-terminal cells, provision is made for an efficient electrical guard system which
adequately shields the measuring electrode. Three-terminal cells shall be preferred when the
most accurate determinations of permittivity are to be made. If necessary, in the case of
measurements for which special screening is required, a removable screening cup can be
added and electrically bonded to the appropriate conductor of the coaxial cable used for the
connection to the bridge (see Figure 2).

---------------------- Page: 14 ----------------------

60247 © IEC:2004 – 21 –
With two-terminal cells, the shield on the lead usually connected to the guard electrode shall be
s
...