IEC 60840:2011

IEC 60840 ®
Edition 4.0 2011-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Power cables with extruded insulation and their accessories for rated voltages
above 30 kV (U = 36 kV) up to 150 kV (U = 170 kV) – Test methods and
m m
requirements
Câbles d'énergie à isolation extrudée et leurs accessoires pour des tensions
assignées supérieures à 30 kV (U = 36 kV) et jusqu'à 150 kV (U = 170 kV) –
m m
Méthodes et exigences d'essai
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IEC 60840 ®
Edition 4.0 2011-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Power cables with extruded insulation and their accessories for rated voltages
above 30 kV (U = 36 kV) up to 150 kV (U = 170 kV) – Test methods and
m m
requirements
Câbles d'énergie à isolation extrudée et leurs accessoires pour des tensions
assignées supérieures à 30 kV (U = 36 kV) et jusqu'à 150 kV (U = 170 kV) –
m m
Méthodes et exigences d'essai
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XB
ICS 29.060.20 ISBN 978-2-88912-752-8

– 2 – 60840 © IEC:2011
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references. 9
3 Terms and definitions . 10
3.1 Definitions of dimensional values (thicknesses, cross-sections, etc.) . 10
3.2 Definitions concerning tests . 11
3.3 Other definitions . 11
4 Voltage designations and materials . 12
4.1 Rated voltages . 12
4.2 Cable insulating materials . 12
4.3 Cable metal screens/sheaths . 12
4.4 Cable oversheathing materials . 12
5 Precautions against water penetration in cables . 12
6 Cable characteristics . 13
7 Accessory characteristics. 13
8 Test conditions . 14
8.1 Ambient temperature . 14
8.2 Frequency and waveform of power frequency test voltages . 14
8.3 Waveform of lightning impulse test voltages . 14
8.4 Relationship of test voltages to rated voltages . 14
8.5 Determination of the cable conductor temperature . 14
9 Routine tests on cables and on the main insulation of prefabricated accessories . 15
9.1 General . 15
9.2 Partial discharge test . 15
9.3 Voltage test . 15
9.4 Electrical test on oversheath of the cable . 15
10 Sample tests on cables . 16
10.1 General . 16
10.2 Frequency of tests . 16
10.3 Repetition of tests . 16
10.4 Conductor examination . 16
10.5 Measurement of electrical resistance of conductor and metal screen . 16
10.6 Measurement of thickness of cable insulation and oversheath . 17
10.6.1 General . 17
10.6.2 Requirements for the insulation . 17
10.6.3 Requirements for the cable oversheath . 17
10.7 Measurement of thickness of metal sheath. 18
10.7.1 Lead or lead alloy sheath . 18
10.7.2 Plain or corrugated aluminium sheath . 18
10.8 Measurement of diameters . 19
10.9 Hot set test for XLPE, EPR and HEPR insulations . 19
10.9.1 Procedure . 19
10.9.2 Requirements . 19
10.10 Measurement of capacitance. 19

60840 © IEC:2011 – 3 –
10.11 Measurement of density of HDPE insulation . 19
10.11.1 Procedure . 19
10.11.2 Requirements . 19
10.12 Lightning impulse voltage test . 19
10.13 Water penetration test. 20
10.14 Tests on components of cables with a longitudinally applied metal tape or
foil, bonded to the oversheath . 20
11 Sample tests on accessories . 20
11.1 Tests on components . 20
11.2 Tests on complete accessory . 20
12 Type tests on cable systems . 20
12.1 General . 20
12.2 Range of type approval . 21
12.3 Summary of type tests . 21
12.4 Electrical type tests on complete cable systems . 22
12.4.1 Test voltage values . 22
12.4.2 Tests and sequence of tests . 22
12.4.3 Bending test . 23
12.4.4 Partial discharge tests . 24
12.4.5 Tan δ measurement . 24
12.4.6 Heating cycle voltage test . 24
12.4.7 Lightning impulse voltage test followed by a power frequency voltage
test . 25
12.4.8 Examination . 25
12.4.9 Resistivity of semi-conducting screens . 25
12.5 Non-electrical type tests on cable components and on complete cable . 26
12.5.1 Check of cable construction . 26
12.5.2 Tests for determining the mechanical properties of insulation before
and after ageing . 26
12.5.3 Tests for determining the mechanical properties of oversheaths
before and after ageing . 27
12.5.4 Ageing tests on pieces of complete cable to check compatibility of
materials . 27
12.5.5 Loss of mass test on PVC oversheaths of type ST . 28
12.5.6 Pressure test at high temperature on oversheaths . 28
12.5.7 Test on PVC oversheaths (ST ST ) at low temperature . 28
1, 2
12.5.8 Heat shock test for PVC oversheaths (ST and ST ) . 29
1 2
12.5.9 Ozone resistance test for EPR and HEPR insulations . 29
12.5.10 Hot set test for EPR, HEPR and XLPE insulations . 29
12.5.11 Measurement of density of HDPE insulation . 29
12.5.12 Measurement of carbon black content of black PE oversheaths (ST
and ST ). 29
12.5.13 Test under fire conditions . 29
12.5.14 Water penetration test . 30
12.5.15 Tests on components of cables with a longitudinally applied metal
tape or foil, bonded to the oversheath . 30
12.5.16 Shrinkage test for PE, HDPE and XLPE insulations . 30
12.5.17 Shrinkage test for PE oversheaths (ST and ST ) . 30
3 7
12.5.18 Determination of hardness of HEPR insulation . 30
12.5.19 Determination of the elastic modulus of HEPR insulation . 31

– 4 – 60840 © IEC:2011
13 Prequalification test of the cable system. 31
13.1 General and range of prequalification test approval . 31
13.2 Prequalification test on complete system . 32
13.2.1 Summary of prequalification tests . 32
13.2.2 Test voltage values . 32
13.2.3 Test arrangement . 32
13.2.4 Heating cycle voltage test . 33
13.2.5 Lightning impulse voltage test . 34
13.2.6 Examination . 34
13.3 Tests for the extension of the prequalification of a cable system. 34
13.3.1 Summary of the extension of prequalification test . 34
13.3.2 Electrical part of the extension of prequalification tests on complete
cable system. 34
14 Type tests on cables . 36
14.1 General . 36
14.2 Range of type approval . 36
14.3 Summary of type tests . 37
14.4 Electrical type tests on completed cables . 37
15 Type tests on accessories . 38
15.1 General . 38
15.2 Range of type approval . 38
15.3 Summary of type tests . 38
15.4 Electrical type tests on accessories . 39
15.4.1 Test voltage values . 39
15.4.2 Tests and sequence of tests . 39
16 Electrical tests after installation . 40
16.1 General . 40
16.2 DC voltage test of the oversheath . 40
16.3 AC voltage test of the insulation . 40
Annex A (informative) Determination of the cable conductor temperature . 47
Annex B (normative) Rounding of numbers . 52
Annex C (informative) List of type, prequalification and extension of prequalification
tests for cable systems, cables and accessories . 53
Annex D (normative) Method of measuring resistivity of semi-conducting screens . 56
Annex E (normative) Water penetration test . 58
Annex F (normative) Tests on components of cables with a longitudinally applied metal
tape or foil, bonded to the oversheath . 60
Annex G (normative) Tests of outer protection for joints . 63
Annex H (normative) Determination of hardness of HEPR insulations . 65
Bibliography . 67

Figure 1 – Example of the test arrangement for the prequalification test. 33
Figure 2 – Example of extension of prequalification test arrangement for the
prequalification of a system with another joint, designed for rigid and flexible installation . 35
Figure A.1 – Typical test set-up for the reference loop and the main test loop . 48
Figure A.2 – Example of an arrangement of the temperature sensors on the conductor
of the reference loop . 49

60840 © IEC:2011 – 5 –
Figure D.1 – Preparation of samples for measurement of resistivity ofconductor and
insulation screens . 57
Figure E.1 – Schematic diagram of apparatus for water penetration test . 59
Figure F.1 – Adhesion of metal foil . 60
Figure F.2 – Example of overlapped metal foil . 61
Figure F.3 – Peel strength of overlapped metal foil . 61
Figure H.1 – Test on surfaces of large radius of curvature . 66
Figure H.2 – Test on surfaces of small radius of curvature . 66

Table 1 – Insulating compounds for cables . 40
Table 2 – Oversheathing compounds for cables . 41
Table 3 – Tan δ requirements for insulating compounds for cables . 41
Table 4 – Test voltages . 41
Table 5 – Non-electrical type tests for insulating and oversheathing compounds for
cables . 42
Table 6 – Test requirements for mechanical characteristics of insulating compounds for
cables (before and after ageing) . 43
Table 7 – Test requirements mechanical characteristics of oversheathing compounds
for cables (before and after ageing) . 44
Table 8 – Test requirements for particular characteristics of insulating compounds for
cables . 45
Table 9 – Test requirements for particular characteristics of PVC oversheathing for
cables . 46
Table C.1 – Type tests on cable systems, on cables and on accessories . 54
Table C.2 – Prequalification tests on cable systems with a calculated nominal
conductor electric stress above 8,0 kV/mm or a calculated nominal insulation electric
stress above 4,0 kV/mm . 54
Table C.3 – Extension of prequalification tests on cable systems with a calculated
nominal conductor electric stress above 8,0 kV/mm or a calculated nominal insulation
electric stress above 4,0 kV/mm . 55
Table G.1 – Impulse voltage tests . 64

– 6 – 60840 © IEC:2011
INTERNATIONAL ELECTROTECHNICAL COMMISSION
______________
POWER CABLES WITH EXTRUDED INSULATION AND
THEIR ACCESSORIES FOR RATED VOLTAGES ABOVE 30 kV
(U = 36 kV) UP TO 150 kV (U = 170 kV) –
m m
TEST METHODS AND REQUIREMENTS
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
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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.
International Standard IEC 60840 has been prepared by IEC technical committee 20: Electric
cables.
This fourth edition cancels and replaces the third edition, published in 2004, and constitutes a
major technical revision.
The significant technical change with respect to the previous edition is as follows:
– introduction of a prequalification test procedure for cables with high electrical stresses and
tested as a cable system including accessories.
NOTE For a more detailed history of events leading up to this fourth edition, see the Introduction.

60840 © IEC:2011 – 7 –
The text of this standard is based on the following documents:
FDIS Report on voting
20/1267/FDIS 20/1277A/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 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
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 8 – 60840 © IEC:2011
INTRODUCTION
The first edition of IEC 60840, published in 1988, dealt only with cables. Accessories were
added to the second edition, published in February 1999, which separately covered test
methods and test requirements for
a) cables alone,
b) cables together with accessories (a cable system).
Some countries then suggested that a better discrimination be made between systems, cables
and accessories, particularly for the lower voltages of the scope, e.g. 45 kV. This was taken
into account in the third edition and is retained in this revision, which gives the type approval
requirements and the range of approvals for
a) cable systems,
b) cables alone,
c) accessories alone.
Manufacturers and users may choose the most appropriate option for type approval.
At its meeting in November 2004, TC 20 decided to prepare a further major revision of
IEC 60840 and concluded that this edition should incorporate the recommendations for testing
HV and EHV extruded cables that were under preparation by CIGRE study committee B1 WG
B1.06. This work was made available as CIGRE technical brochure No. 303, before the
meeting of TC 20 in October 2006. The brochure, entitled “Revision of qualification procedures
for extruded (extra) high voltage a.c. underground cables”, has therefore been considered by
TC 20, and considerable parts implemented in this standard. Cables with high electrical
stresses at the conductor screen and/or insulation screen are now required to undergo a
prequalification test procedure (simplified compared to that in IEC 62067) as a cable system
inclusive of accessories.
Additionally the following other significant changes to this standard have been introduced:
a) The clause numbering of this standard and IEC 62067 (which has been revised at the
same time as this standard) has been coordinated to achieve as much commonality as
possible to assist users who use both standards.
b) In the case of the sample test, the lightning impulse voltage test is no longer followed by a
power frequency voltage test.
A list of relevant CIGRE references is given in the bibliography.

60840 © IEC:2011 – 9 –
POWER CABLES WITH EXTRUDED INSULATION AND
THEIR ACCESSORIES FOR RATED VOLTAGES ABOVE 30 kV
(U = 36 kV) UP TO 150 kV (U = 170 kV) –
m m
TEST METHODS AND REQUIREMENTS
1 Scope
This International Standard specifies test methods and requirements for power cable systems,
cables alone and accessories alone, for fixed installations and for rated voltages above 30 kV
(U = 36 kV) up to and including 150 kV (U = 170 kV).
m m
The requirements apply to single-core cables and to individually screened three-core cables
and to their accessories for usual conditions of installation and operation, but not to special
cables and their accessories, such as submarine cables, for which modifications to the
standard tests may be necessary or special test conditions may need to be devised.
This standard does not cover transition joints between cables with extruded insulation and
paper insulated cables.
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.
NOTE The IEC 60811 series is currently undergoing a revision, which will lead to a restructuring of its parts. A
description of this, as well as a cross-reference table between the current and planned parts will be given in
IEC 60811-100.
IEC 60060-1, High-voltage test techniques – Part 1: General definitions and test requirements
IEC 60183, Guide to the selection of high-voltage cables
IEC 60228, Conductors of insulated cables
IEC 60229:2007, Electric cables – Tests on extruded oversheaths with a special protective
function
IEC 60230, Impulse tests on cables and their accessories
IEC 60287-1-1:2006, Electric cables – Calculation of the current rating – Part 1-1: Current
rating equations (100 % load factor) and calculation of losses – General
IEC 60332-1-2, Tests on electric and optical fibre cables under fire conditions – Part 1-2: Test
for vertical flame propagation for a single insulated wire or cable – Procedure for 1 kW pre-
mixed flame
IEC 60811-1-1:1993, Common test methods for insulating and sheathing materials of electric
cables – Part 1: Methods for general application – Section 1: Measurement of thickness and
overall dimensions – Tests for determining the mechanical properties
Amendment 1 (2001)
– 10 – 60840 © IEC:2011
IEC 60811-1-2:1985, Common test methods for insulating and sheathing materials of electric
cables – Part 1: Methods for general application – Section Two: Thermal ageing methods
Amendment 1 (1989)
Amendment 2 (2000)
IEC 60811-1-3:1993, Common test methods for insulating and sheathing materials of electric
cables – Part 1-3: General application – Methods for determining the density – Water
absorption tests – Shrinkage test
Amendment 1 (2001)
IEC 60811-1-4:1985, Common test methods for insulating and sheathing materials of electric
cables – Part 1: Methods for general application – Section Four: Tests at low temperature
Amendment 1 (1993)
Amendment 2 (2001)
IEC 60811-2-1:1998, Common test methods for Insulating and sheathing materials of electric
and optical cables –Part 2-1: Methods specific to elastomeric compounds – Ozone resistance,
hot set and mineral oil immersion tests
Amendment 1 (2001)
IEC 60811-3-1:1985, Common test methods for insulating and sheathing materials of electric
cables – Part 3-1: Methods specific to PVC compounds –Pressure test at high temperature –
Tests for resistance to cracking
Amendment 1 (1994)
Amendment 2 (2001)
IEC 60811-3-2:1985, Common test methods for insulating and sheathing materials of electric
cables – Part 3: Methods specific to PVC compounds –Loss of mass test – Section two:
Thermal stability test
Amendment 1 (1993)
Amendment 2 (2003)
IEC 60811-4-1:2004, Insulating and sheathing materials of electric and optical cables –
Common test methods – Part 4-1: Methods specific to polyethylene and polypropylene
compounds – Resistance to environmental stress cracking –Measurement of the melt flow
index – Carbon black and/or mineral filler content measurement in polyethylene by direct
combustion – Measurement of carbon black content by thermogravimetric analysis (TGA) –
Assessment of carbon black dispersion in polyethylene using a microscope
IEC 60885-3, Electrical test methods for electric cables – Part 3: Test methods for partial
discharge measurements on lengths of extruded power cables
ISO 48, Rubber, vulcanized or thermoplastic – Determination of hardness (hardness between
10 IRHD and 100 IRHD)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 Definitions of dimensional values (thicknesses, cross-sections, etc.)
3.1.1
nominal value
value by which a quantity is designated and which is often used in tables
NOTE Usually, in this standard, nominal values give rise to values to be checked by measurements taking into
account specified tolerances.
60840 © IEC:2011 – 11 –
3.1.2
median value
when several test results have been obtained and ordered in an increasing (or decreasing)
succession, middle value if the number of available values is odd, and mean of the two middle
values if the number is even
3.2 Definitions concerning tests
3.2.1
routine test
tests made by the manufacturer on each manufactured component (length of cable or
accessory) to check that the component meets the specified requirements
3.2.2
sample test
tests made by the manufacturer on samples of completed cable or components taken from a
completed cable or accessory, at a specified frequency as to verify that the finished product
meets the specified requirements
3.2.3
type test
tests made before supplying on a general commercial basis a type of cable system or cable or
accessory covered by this standard, in order to demonstrate satisfactory performance
characteristics to meet the intended application
NOTE Once successfully completed, these tests need not be repeated, unless changes are made in the cable or
accessory with respect to materials, manufacturing process, design or design electrical stress levels, which might
adversely change the performance characteristics.
3.2.4
prequalification test
test made before supplying on a general commercial basis a type of cable system covered by
this standard, in order to demonstrate satisfactory long term performance of the complete
cable system
3.2.5
extension of prequalification test
tests made before supplying on a general commercial basis a type of cable system covered by
this standard, in order to demonstrate satisfactory long term performance of the complete
cable system, taking into account an already prequalified cable system
3.2.6
electrical test after installation
tests made to demonstrate the integrity of the cable system as installed
3.3 Other definitions
3.3.1
cable system
cable with installed accessories including components used for thermo-mechanical restraint of
systems limited to those used for terminations and joints only
3.3.2
nominal electrical stress
electrical stress calculated at U using nominal dimensions
– 12 – 60840 © IEC:2011
4 Voltage designations and materials
4.1 Rated voltages
In this standard, the symbols U , U and U are used to designate the rated voltages of cables
0 m
and accessories where these symbols have the meanings given in IEC 60183.
4.2 Cable insulating materials
This standard applies to cables insulated with one of the materials listed in Table 1. It also
specifies for each type of insulating compound the maximum operating conductor temperatures
on which the specified test conditions are based.
4.3 Cable metal screens/sheaths
This standard applies to the various designs in use. It covers designs providing a radial
watertightness and other designs.
Designs that provide radial watertightness mainly consist of
• metal sheaths,
• longitudinally applied metal tapes or foils bonded to the oversheath,
• composite screens, involving a bunch of wires and, in addition, either a metal sheath or a
metal tape or foil bonded to the oversheath, acting as a radial water impermeable barrier
(see Clause 5),
and other designs such as
• metal tapes or foils not bonded to the oversheath,
• bunch of metal wires only.
NOTE In all cases the metal screen/sheath should be able to carry the total fault current.
4.4 Cable oversheathing materials
Tests are specified for four types of oversheath, as follows:
– ST and ST based on polyvinyl chloride (PVC);
1 2
– ST and ST based on polyethylene (PE).
3 7
The choice of the type of oversheath depends on the design of the cable and the mechanical,
thermal and fire constraints during installation and operation.
The maximum conductor temperatures in normal operation for the different types of
oversheathing materials covered by this standard are given in Table 2.
NOTE For some applications the oversheath can be covered by a functional layer (e.g. semi-conductive).
5 Precautions against water penetration in cables
When cable systems are installed in ground, in easily flooded galleries or in water, a radial
water impermeable barrier around the cable is recommended.
NOTE A test for radial water penetration is currently not available.
Longitudinal water barriers may also be applied in order to avoid the need to replace long
sections of cable in case of damage in the presence of water.

60840 © IEC:2011 – 13 –
A test for longitudinal water penetration is given in 12.5.14.
6 Cable characteristics
For the purpose of carrying out the cable system or cable tests described in this standard and
recording the results, the cable shall be identified. The following characteristics shall be known
or declared:
a) Name of manufacturer, type, designation and manufacturing date or date code.

b) Rated voltage: values shall be given for U , U, U (see 4.1 and 8.4).
0 m
c) Type of conductor, its material and nominal cross-sectional area, in square millimetres;
conductor construction; presence, if any, and nature of measures taken to reduce skin
effect; presence, if any, and nature of measures taken to achieve longitudinal
watertightness; if the nominal cross-sectional area is not in accordance with IEC 60228,
the d.c. conductor resistance, corrected to 1 km length and to 20 °C.
) (see 4.2). If the insulation is XLPE,
d) Material and nominal thickness of insulation (t
n
special additives shall be declared if the higher value of tan δ according to Table 3 is
applicable.
e) Type of manufacturing process for insulation system.
f) Presence, if any, and nature of watertightness measures in the screening area.
g) Material and construction of metal screen, e.g. number and diameter of wires. (The d.c.
resistance of the metal screen shall be declared.) Material, construction and nominal
thickness of metal sheath, or longitudinally applied metal tape or foil bonded to the
oversheath, if any.
h) Material and nominal thickness of oversheath.
i) Nominal diameter of the conductor (d).
j) Nominal overall diameter of the cable (D).
k) Nominal inner diameter (d ) and calculated nominal outer diameter (D ) of the insulation.
ii io
l) Nominal capacitance, corrected to 1 km length, between conductor and metal
screen/sheath.
m) Calculated nominal electrical stress at conductor screen (E ) and at insulation screen (E ):
i o
2U
E =
i
d ×ln(D / d )
ii io ii
2U
E =
o
D ×ln(D / d )
io io ii
where
D = d + 2t ;
io ii n
D is the calculated nominal outer diameter of the insulation;
io
d is the declared nominal inner diameter of the insulation;
ii
t is the declared nominal insulation thickness.
n
The value of U is given in Table 4.
7 Accessory characteristics
For the purpose of carrying out the cable system or accessory tests described in this standard
and recording the results, the accessory shall be identified.

– 14 – 60840 © IEC:2011
The following characteristics shall be known or declared:
a) cables used for testing accessories shal
...