IEC 60893-2:2023

IEC 60893-2 ®
Edition 3.0 2023-11
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Insulating materials – Industrial rigid laminated sheets based on thermosetting
resins for electrical purposes –
Part 2: Methods of test
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IEC 60893-2 ®
Edition 3.0 2023-11
REDLINE VERSION
INTERNATIONAL
STANDARD
colour
inside
Insulating materials – Industrial rigid laminated sheets based on thermosetting
resins for electrical purposes –
Part 2: Methods of test
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.035.01  ISBN 978-2-8322-7858-1
– 2 – IEC 60893-2:2023 RLV © IEC 2023
CONTENTS
FOREWORD . 5
INTRODUCTION . 2
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 Conditioning of test specimens . 10
5 Dimensions. 10
5.1 Thickness . 10
5.1.1 General . 10
5.1.2 Test apparatus for reference method . 10
5.1.3 Procedure for reference method . 10
5.1.4 Results . 11
5.2 Flatness . 11
5.2.1 General . 11
5.2.2 Test specimens . 11
5.2.3 Test method . 11
5.2.4 Results . 11
6 Mechanical tests . 11
6.1 Flexural strength . 11
6.1.1 General . 11
6.1.2 Test specimens . 11
6.1.3 Test method . 11
6.1.4 Results . 12
6.2 Modulus of elasticity in flexure . 12
6.2.1 General . 12
6.2.2 Test specimens . 12
6.2.3 Test method . 12
6.2.4 Results . 12
6.3 Compressive strength . 12
6.3.1 General . 12
6.3.2 Test specimens . 12
6.3.3 Test method . 12
6.3.4 Results . 12
6.4 Impact strength . 12
6.4.1 General . 12
6.4.2 Charpy Impact strength . 12
6.4.3 Izod impact strength . 13
6.5 Shear strength parallel to laminations . 13
6.5.1 General . 13
6.5.2 Test specimens . 13
6.5.3 Test method . 14
6.5.4 Results . 14
6.6 Tensile strength . 14
6.6.1 General . 14
6.6.2 Test specimens . 14
6.6.3 Test method . 14

6.6.4 Results . 14
7 Electrical tests . 15
7.1 Electric strength and breakdown voltage . 15
7.1.1 General . 15
7.1.2 Test specimens . 15
7.1.3 Test method . 15
7.2 Permittivity and dissipation factor . 15
7.2.1 General requirements . 15
7.2.2 Methods . 16
7.2.3 Principles of the methods . 16
7.2.4 Measuring instruments. 17
7.2.5 Method A: Direct measurement technique . 17
7.2.6 Method B: Air substitution technique . 20
7.2.7 Method C: Two fluid immersion technique . 22
7.2.8 Test report . 25
7.3 Insulation resistance after immersion in water . 26
7.3.1 General . 26
7.3.2 Test specimens . 26
7.3.3 Test method . 26
7.3.4 Results . 26
7.4 Comparative and proof tracking indices . 26
7.4.1 General . 26
7.4.2 Test specimens . 26
7.4.3 Test method . 27
7.4.4 Results . 27
7.5 Tracking and erosion resistance . 27
7.5.1 General . 27
7.5.2 Test specimens . 27
7.5.3 Test method . 27
7.5.4 Results . 27
8 Thermal tests . 27
8.1 Thermal endurance . 27
8.1.1 General . 27
8.1.2 Test specimens . 27
8.1.3 Test method . 27
8.1.4 Results . 27
8.2 Flammability . 28
8.2.1 General . 28
8.2.2 Test specimens . 28
8.2.3 Test method . 28
8.2.4 Results . 28
9 Other tests . 28
9.1 Density . 28
9.1.1 General . 28
9.1.2 Test specimens . 28
9.1.3 Test method . 28
9.1.4 Results . 28
9.2 Water absorption . 28
9.2.1 General . 28

– 4 – IEC 60893-2:2023 RLV © IEC 2023
9.2.2 Test specimens . 28
9.2.3 Test method . 28
9.2.4 Results . 28
Annex A (informative) Modes of representation of capacitance . 34
Annex B (informative) Liquids of known permittivity values . 35
Bibliography . 36

Figure 1 – Test specimens for impact strength test . 29
Figure 2 – Device for testing parallel shearing strength . 30
Figure 3 – Example of electrode system for method A . 31
Figure 4 – Example of electrode system for method B . 32
Figure 5 – Example of electrode system for method C . 33
Figure A.1 – Equivalent parallel and series representation of a capacitor . 34

Table 1 – Sequence employed for routine measurements . 24
Table B.1 – Liquids of know permittivity values . 35

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INSULATING MATERIALS –
INDUSTRIAL RIGID LAMINATED SHEETS
BASED ON THERMOSETTING RESINS
FOR ELECTRICAL PURPOSES –
Part 2: Methods of test
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
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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9) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes
made to the previous edition IEC 60893-2:2003. A vertical bar appears in the margin
wherever a change has been made. Additions are in green text, deletions are in
strikethrough red text.
– 6 – IEC 60893-2:2023 RLV © IEC 2023
IEC 60893-2 has been prepared by IEC technical committee 15: Solid electrical insulating
materials. It is an International Standard.
This third edition cancels and replaces the second edition published in 2003. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) removal of reference to withdrawn specification IEC 60167:1964;
b) inclusion of reference to IEC 62631-3-3:2015, which supersedes IEC 60167:1964. Details
in 6.3 have been updated accordingly. The actual performance of the test has not changed;
c) normative references have been updated.
The text of this International Standard is based on the following documents:
Draft Report on voting
15/1017/FDIS 15/1023/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 60893 series, published under the general title Insulating materials
– Industrial rigid laminated sheets based on thermosetting resins for electrical purposes, can
be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
IMPORTANT – The "colour inside" logo on the cover page of this document 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.

INTRODUCTION
This document is one of a series which deals with industrial rigid laminated sheets based on
thermosetting resins for electrical purposes.
This series consists of four parts:
• Part 1: Definitions, designations and general requirements (IEC 60893-1);
• Part 2: Methods of test (IEC 60893-2);
• Part 3: Specifications for individual materials (IEC 60893-3);
• Part 4: Typical values (IEC TR 60893-4).

– 8 – IEC 60893-2:2023 RLV © IEC 2023
INSULATING MATERIALS –
INDUSTRIAL RIGID LAMINATED SHEETS
BASED ON THERMOSETTING RESINS
FOR ELECTRICAL PURPOSES –
Part 2: Methods of test
1 Scope
This part of IEC 60893 describes methods of test for the materials defined in IEC 60893-1
(referred to also as Part 1).
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 60112, Method for determining the comparative and the proof tracking indices of solid
insulating materials under moist conditions the determination of the proof and the comparative
tracking indices of solid insulating materials
IEC 60167:1964, Methods of test for the determination of the insulation resistance of solid
insulating materials
IEC 60212:19712010, Standard conditions for use prior to and during the testing of solid
electrical insulating materials
IEC 60216-1:20012013, Electrical insulating materials – Properties of Thermal endurance
properties – Part 1: Ageing procedures and evaluation of test results
IEC 60243-1:19982013, Electric strength of solid insulating materials – Test methods – Part 1:
Tests at power frequencies
IEC 60250:1969, 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 60296:19822012 , Specification for unused mineral insulating oils for transformers and
switchgear Fluids for electrotechnical applications – Unused mineral insulating oils for
transformers and switchgear
IEC 60587:19842007 , Test method for evaluating resistance to tracking and erosion of
electrical insulating materials used under severe ambient conditions Electrical insulating
materials used under severe ambient conditions – Test methods for evaluating resistance to
tracking and erosion
___________
A fifth edition of this standard has been published in 2020.
A fourth edition of this standard has been published in 2022.

IEC 60695-11-10:19992013, Fire hazard testing – Part 11-10: Test flames – 50 W horizontal
and vertical flame test methods
IEC 60893-1, Insulating materials – Industrial rigid laminated sheets based on thermosetting
resins for electrical purposes – Part 1: Definitions, designations and general requirements
IEC 60893-3 (all parts 3), Insulating materials – Industrial rigid laminated sheets based on
thermosetting resins for electrical purposes – Part 3: Specifications for individual materials
IEC TR 60893-4:2003, Insulating materials – Industrial rigid laminated sheets based on
thermosetting resins for electrical purposes – Part 4: Typical values
IEC 62631-3-3:2015, Dielectric and resistive properties of solid insulating materials – Part 3-3:
Determination of resistive properties (DC methods) – Insulation resistance
ISO 62:19992008, Plastics – Determination of water absorption
ISO 178:20012010 , Plastics – Determination of flexural properties
ISO 179-1:2000 , Plastics – Determination of Charpy impact properties – Part 1: Non-
instrumented impact test
ISO 179-2:1997 , Plastics – Determination of Charpy impact properties – Part 2: Instrumented
impact test
ISO 180:2000 , Plastics – Determination of Izod impact strength
ISO 527-1:19932012 , Plastics – Determination of tensile properties – Part 1: General principles
ISO 527-4:1997 , Plastics – Determination of tensile properties – Part 4: Test conditions for
isotropic and orthotropic fibre-reinforced plastic composites
ISO 604:2002, Plastics – Determination of compressive properties
ISO 1183:1987, Plastics – Methods for determining the density and relative density of non-
cellular plastics
ISO 1183-1:2012 , Plastics – Methods for determining the density of non-cellular plastics –
Part 1: Immersion method, liquid pyknometer method and titration method
___________
Use edition 2 when published.
A sixth edition of this standard has been published in 2019.
A third edition of this standard has been published in 2023.
A second edition of this standard has been published in 2020.
A fifth edition of this standard has been published in 2023.
A third edition of this standard has been published in 2019.
A third edition of this standard has been published in 2023.
A third edition of this standard has been published in 2019.

– 10 – IEC 60893-2:2023 RLV © IEC 2023
ISO 3611:19782010 , Micrometer callipers for external measurement Geometrical product
specifications (GPS) – Dimensional measuring equipment: Micrometers for external
measurements – Design and metrological characteristics
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
4 Conditioning of test specimens
Unless otherwise specified, test specimens shall be conditioned for at least 24 h in standard
atmosphere B according to IEC 60212:2010 (temperature 23 °C ± 2 K 23 ± 2 °C, relative
humidity (50 ± 5) %).
Unless otherwise specified, each specimen shall be tested in the conditioning atmosphere and
at the conditioning temperature, or the tests shall commence within 3 min of removal of each
test specimen from the conditioning atmosphere.
Where testing at an elevated temperature is required in one of the specification sheets of
IEC 60893-3, test specimens shall be conditioned for 1 h at that elevated temperature
immediately before testing.
5 Dimensions
5.1 Thickness
5.1.1 General
Any method which enables the thickness of the laminated sheet to be measured at an
appropriate number of points may be used, provided that the equipment used and the method
of measurement are capable of a precision of 0,01 mm or better.
The following reference method has been shown to be suitable and shall be used in cases
of dispute.
5.1.2 Test apparatus for reference method
In case of dispute, an external screw type micrometer in accordance with ISO 3611 having faces
with diameters between 6 mm and 8 mm shall be used.
5.1.3 Procedure for reference method
Measure the thickness of the rigid laminated sheet as delivered to the nearest 0,01 mm at eight
points, two along each edge but not less than 20 mm from the edge.
___________
A third edition of this standard has been published in 2023.

5.1.4 Results
Report the maximum and minimum measured values and the arithmetic mean of all measured
values in mm.
5.2 Flatness
5.2.1 General
This test is applicable to all sheets having a thickness of 3 mm or greater.
5.2.2 Test specimens
The test specimen shall be the whole sheet or panel under test in the ‘as received’ condition.
5.2.3 Test method
When any sheet of nominal thickness 3,0 mm or more is placed without restraint, concave side
up, on a flat surface, the departure at any point of the upper surface of the sheet from a light
straight edge 1 000 mm or 500 mm in length, laid in any direction upon it, shall not exceed the
value given in the relevant sheet of IEC 60893-3 appropriate to the material, its thickness and
length of straight edge. The mass of the 1 000 mm straight edge shall not exceed 800 g, and the
mass of the 500 mm straight edge shall not exceed 400 g.
5.2.4 Results
Report the maximum measured deviation from flatness in mm.
NOTE In cases where the sheet deviates from flatness in two directions, is saddle-shaped,
measure both deviations and report the highest.
6 Mechanical tests
6.1 Flexural strength
6.1.1 General
The flexural strength is defined as the flexural stress at rupture. It shall be determined by the
method specified in ISO 178. Method A shall be used.
6.1.2 Test specimens
Cut the test specimens from the sheet to be tested with their major axes parallel to the sides of
the sheet. Test five test specimens in each direction, except for types with fibres aligned mainly
in the same direction. In such cases, cut five specimens only, with their long axis parallel to the
direction of the fibres.
If the nominal thickness of the sheet to be tested is more than 10 mm (20 mm in the case of
types PF WV), reduce the thickness of the test specimens to 10 mm (20 mm in the case
of PF WV).
When it is necessary to reduce the thickness of a test specimen, machine it, leaving one face
of the sheet intact. In such cases, test specimens shall be tested with the original surface of
the sheet in contact with the two supports.
6.1.3 Test method
The test shall be carried out with the load applied perpendicular to the plane of the laminations.
The test speed shall be 5 mm/min with a tolerance of ±20 %.

– 12 – IEC 60893-2:2023 RLV © IEC 2023
6.1.4 Results
Report the arithmetic mean of the results for each direction in MPa. Take the lower of the two
mean values as the minimum flexural strength of the sheet under test, except in cases where
the reinforcing fibres run mainly in one direction. In such cases, take the mean value obtained
in this direction.
6.2 Modulus of elasticity in flexure
6.2.1 General
The following test method shall be used in order to determine the modulus of elasticity in flexure.
6.2.2 Test specimens
The specimens shall be in the same form as described for the flexural strength test described
in 6.1.2 above.
6.2.3 Test method
Modulus of elasticity shall be determined by the method specified in ISO 178.
6.2.4 Results
Results shall be expressed in MPa.
6.3 Compressive strength
6.3.1 General
The following test method shall be used in order to determine the compressive strength.
6.3.2 Test specimens
Specimens shall be cut from the sheet under test as described in ISO 604.
6.3.3 Test method
Compressive strength shall be determined by the method specified in ISO 604 with the load
applied perpendicular to the plane of the laminations.
6.3.4 Results
Results shall be expressed in MPa.
6.4 Impact strength
6.4.1 General
This test is only applicable to sheets of nominal thickness equal to or greater than 5 mm.
6.4.2 Charpy Impact strength
6.4.2.1 Test specimens
Test specimens shall be cut from the sheet under test in accordance with Figure 1 a). Five
specimens, with a thickness between 5 mm and 10 mm, shall be tested in each direction, except
for types with fibres aligned mainly in the same direction. In such cases, cut five specimens
only, with their longitudinal axis parallel to the direction of the fibres.

If the nominal thickness of the sheet to be tested is greater than 10 mm, reduce the thickness
of the test specimen to 10 mm by machining equal amounts from both faces of the sheet.
6.4.2.2 Test method
The Charpy impact strength shall be determined in the edgewise direction as described by the
method given in ISO 179-1 and ISO 179-2 except that the specimens shall be as described
above, and the span shall be 70 mm. The material shall be tested with the major axes in each
direction parallel to the sides of the sheet, except in the case of materials whose fibres lie
mainly in the same direction. For these materials only specimens with their longitudinal axis
parallel to the direction of the fibres shall be tested.
6.4.2.3 Results
Report the arithmetic mean of the results for each direction in kJ/m . Take the lower of the two
mean values as the minimum Charpy impact strength of the sheet under test, except in cases
where the reinforcing fibres run mainly in one direction. In such cases, take the mean value
obtained in this direction.
6.4.3 Izod impact strength
6.4.3.1 Test specimens
The dimensions of the specimens shall be as described in Figure 1 b). Five specimens, with a
thickness between 5 mm and 10 mm, shall be tested in each direction, except for types with
fibres aligned mainly in the same direction. In such cases, cut five specimens only, with their
longitudinal axis parallel to the direction of the fibres.
If the nominal thickness of the sheet to be tested is greater than 10 mm, reduce the thickness
of the test specimen to 10 mm by machining equal amounts from both faces of the sheet.
6.4.3.2 Test method
The Izod impact strength shall be determined in the edgewise direction as described by the
method given in ISO 180. The material shall be tested with the major axes in each direction
parallel to the sides of the sheet, except in the case of materials whose fibres lie mainly in the
same direction. For these materials only, specimens with their longitudinal axis parallel to
the direction of the fibres shall be tested.
6.4.3.3 Results
Report the arithmetic mean of the results for each direction in kJ/m . Take the lower of the two
mean values as the minimum Izod impact strength of the sheet under test, except in cases
where the reinforcing fibres run mainly in one direction. In such cases, take the mean value
obtained in this direction.
6.5 Shear strength parallel to laminations
6.5.1 General
The shear strength parallel to laminations test provides data that gives an indication of the
degree of bonding or adhesion between laminations. The test is only applicable to sheets
of nominal thickness greater than 5 mm.
6.5.2 Test specimens
Rectangular test specimens are cut with the following dimensions:
Length 20 mm ± 0,1 mm
– 14 – IEC 60893-2:2023 RLV © IEC 2023
Width and thickness 5 mm
− 0,15
Cut the test specimens from the sheet to be tested with their major axes parallel to the sides of
the sheet. Prepare five sets of test specimens for each direction, each set of specimens
comprising two pieces.
The two specimens in each pair shall have widths (dimension along the laminations orthogonal
to the length) identical within 0,01 mm.
6.5.3 Test method
Two test specimens are simultaneously subjected to shearing stress in the device shown in
Figure 2.
The test specimens shall be arranged so that the shearing stress acts in a plane parallel to the
laminations. The relative rate of movement of the cross head of the testing machine shall be
2 mm/min with a tolerance of ±20 %.
6.5.4 Results
Calculate the shear strength by dividing the shear force through the total shear plane area
of 2 × 100 mm .
Report the arithmetic mean value of the results for each direction in MPa and take the lower
of the two mean values as the parallel shearing strength of the sheet under test.
6.6 Tensile strength
6.6.1 General
Tensile strength defined as tensile stress at maximum load shall be determined by the method
specified in ISO 527-4, in conjunction with ISO 527-1.
6.6.2 Test specimens
Specimens shall be cut from the sheet under test with the major axis in each direction parallel
to the sides of the sheet. Five specimens of nominal thickness between 1,5 mm and 10,0 mm
shall be prepared from each direction according to type 1 of ISO 527-4, except in the case of
materials whose fibres lie mainly in the same direction. For these materials, only specimens
with their longitudinal axis parallel to the direction of the fibres shall be tested.
If the sheet to be tested is more than 10 mm thick, reduce the thickness of the test specimens
to 10 mm by machining equal amounts from each face.
6.6.3 Test method
Carry out the test as described in ISO 527-4. The rate of separation of the jaws of the testing
machine shall be 5 mm/min with a tolerance of ±20 %.
6.6.4 Results
Report the arithmetic mean of the results for each direction in MPa. Take the lower of the two
mean values as the minimum tensile strength of the sheet under test, except in cases where
the reinforcing fibres run mainly in one direction. In such cases, take the mean value obtained
in this direction.
7 Electrical tests
7.1 Electric strength and breakdown voltage
7.1.1 General
Electric strength and breakdown voltage shall be determined by the methods specified in
IEC 60243-1, which describes both the step-by-step and 60 s proof tests. Either test method
may be used. Unless otherwise specified the test shall be carried out at 90 °C ± 2 K 90 ± 2 °C
in mineral oil as described in IEC 60296:2012, which is reasonably free from decomposition
products. Immerse the specimens in oil maintained at that temperature for not less than 0,5 h
and not more than 1 h immediately before test.
7.1.2 Test specimens
For electric strength, test three specimens normal to laminations. For breakdown voltage, test
three specimens parallel to the laminations.
Test specimens shall be cut from the sheet under test. Specimen dimensions shall be as
described in IEC 60243-1.
7.1.3 Test method
7.1.3.1 General
Test the material using either the 20 s step-by-step test as described in 10.2 of
IEC 60243-1:2013, or using the 60 s proof test as described in 10.6 of IEC 60243-1:2013.
7.1.3.2 Electric strength perpendicular to laminations
For thicknesses not greater than 3 mm, the material shall be tested perpendicular to the
laminations. The upper electrode shall be 25 mm in diameter and the lower electrode shall be
75 mm in diameter according to IEC 60243-1.
NOTE This test is usually not required for thicknesses above 3 mm, in the Part 3 series. When
it is required, reduce the thickness of the specimens to 3 mm by machining one face according
to 5.2.1.4 of IEC 60243-1:2013, and use the requirement of the 3 mm thickness.
7.1.3.3 Breakdown voltage parallel to laminations
For thicknesses above 3 mm and less than or equal to 10 mm, the material shall be tested
edgewise in accordance with 5.3.3 of IEC 60243-1:2013 (taper pin electrodes) or with 5.3.2.1
of IEC 60243-1:2013, (parallel plate electrodes), and for thicknesses above 10 mm in
accordance with 5.3.2.1 of IEC 60243-1:2013 (parallel plate electrodes). For types with their
fibres mainly in the same direction the test shall be carried out in the fibre direction.
7.1.3.4 Results
For each of the above tests, the arithmetic mean of the test results shall be taken as the result.
The minimum value shall also be reported. Results of the electric strength perpendicular to
lamination test shall be reported in kV/mm, and the results of the breakdown voltage test parallel
to laminations, shall be reported in kV.
7.2 Permittivity and dissipation factor
7.2.1 General requirements
Permittivity and dissipation factor may be determined by any one of the three methods given in
7.2.2. Unless otherwise indicated in the relevant clauses of IEC TR 60893-4, the specimens
shall be conditioned for (96 ± 1) h in air at a temperature of 105 °C ± 5 K 105 ± 5 °C with a

– 16 – IEC 60893-2:2023 RLV © IEC 2023
relative humidity of less than 20 % (dry hot standard atmosphere according to IEC 60212:2010).
At the end of this time, allow the specimens to cool to room temperature in a desiccator. Apply
the electrodes, and/or otherwise make the measurements within 10 min of removal of each
specimen from the desiccator.
Where intimate electrodes are required, silver paint shall be painted centrally on the test
specimen. Conducting rubber, evaporated and sputtered electrodes shall not be used.
Unless otherwise specified, measurements shall be made at a temperature of 23 °C ± 2 K
23 ± 2 °C at a power frequency between 48 Hz and 62 Hz or at a radio frequency of 1 MHz.
To ensure that the specimens, the electrodes and the immersion fluid are in thermal equilibrium
with their environment during the measurement, they should all be kept at the measurement
temperature for not less than 0,5 h immediately before the measurement. The test voltage shall
be high enough to provide the required sensitivity, but low enough to avoid dielectric heating
and discharges at the edges of the electrodes.
In all three methods, the test shall be carried out on two test specimens unless otherwise
specified. At all times, the specimens shall be handled with stainless steel flat-faced forceps
to minimize the likelihood of damage or contamination.
The average of the two determinations shall be taken as the result.
Reference to IEC 60250:1969 [1] should be made for additional guidance and clarification.
NOTE 1 In total, the three methods described maycan be used for shee
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