IEC 63026:2019

Submarine power cables with extruded insulation and their accessories for rated voltages from 6 kV (<em>U</em>_m = 7,2 kV) up to 60 kV (<em>U</em>_m = 72,5 kV) - Test methods and requirements

IEC 63026:2019 specifies test methods and requirements for power cable systems, cables with extruded insulation and their accessories for fixed submarine installations, for rated voltages from 6 kV (Um = 7,2 kV) up to 60 kV (Um = 72,5 kV).
This document includes the electrical tests and the physical tests on materials and components as well as the specific mechanical tests that are applicable to submarine cable systems.
The requirements apply to armoured single-core cables and three-core cables in combination with their accessories, terminations and joints for usual conditions of installation and operation, but not to special cables and their accessories, such as submarine cables for dynamic applications (i.e. for direct connection to a floating structure), for which modifications to the standard tests can be necessary or special test conditions be devised.
This document is applicable to submarine cables installed in permanently submerged conditions with water depths up to 250 m.
This document does not include accessories having a mechanical function only, such as hang-offs or armour clamps.

General Information

• Status: Published
• Publication Date: 10-Dec-2019
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 29.060.20 - Cables
• Technical Committee: TC 20 - Electric cables
• Drafting Committee: WG 16 - TC 20/WG 16
• Current Stage: PPUB - Publication issued
• Start Date: 20-Dec-2019
• Completion Date: 11-Dec-2019

Standards Content (Sample)

IEC 63026
®

Edition 1.0 2019-12
INTERNATIONAL
STANDARD

colour
inside


Submarine power cables with extruded insulation and their accessories for
rated voltages from 6 kV (U = 7,2 kV) up to 60 kV (U = 72,5 kV) –
m m
Test methods and requirements
IEC 63026:2019-12(en)

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IEC 63026

®


Edition 1.0 2019-12




INTERNATIONAL



STANDARD








colour

inside










Submarine power cables with extruded insulation and their accessories for

rated voltages from 6 kV (U = 7,2 kV) up to 60 kV (U = 72,5 kV) –
m m

Test methods and requirements


























INTERNATIONAL

ELECTROTECHNICAL


COMMISSION





ICS 29.060.20 ISBN 978-2-8322-7642-6




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


® Registered trademark of the International Electrotechnical Commission

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– 2 – IEC 63026:2019 © IEC 2019
CONTENTS
FOREWORD . 7
INTRODUCTION . 9
1 Scope . 10
2 Normative references . 10
3 Terms and definitions . 11
3.1 Definitions of dimensional values (thicknesses, cross-sections, etc.) . 12
3.2 Definitions concerning tests . 12
3.3 Other definitions . 12
3.4 Definitions concerning test objects . 13
4 Voltage designations, materials and rounding of numbers . 14
4.1 Rated voltages . 14
4.2 Cable insulating compounds . 15
4.3 Rounding of numbers . 15
5 Cable construction . 16
5.1 General . 16
5.2 Conductors . 16
5.3 Insulation . 16
5.4 Screening . 16
5.5 Metal screen . 17
5.6 Core oversheathing materials . 17
5.7 Assembly of three-core cables and fillers . 17
5.8 Cable armour . 17
5.9 Cable outer serving . 18
5.10 Packaging . 18
6 Cable characteristics . 18
7 Accessory characteristics . 19
8 Test conditions . 19
8.1 Ambient temperature. 19
8.2 Frequency and waveform for AC voltage tests . 19
8.3 Lightning impulse test . 19
8.4 Relationship of test voltages to rated voltages . 19
8.5 Determination of the cable conductor temperature . 20
9 Routine tests on cables and accessories . 20
9.1 General . 20
9.2 Test on manufacturing lengths . 20
9.2.1 Partial discharge test . 20
9.2.2 AC voltage test . 20
9.3 Test on factory joints. 21
9.4 Test on delivery lengths . 21
9.4.1 General . 21
9.4.2 AC voltage test . 21
9.4.3 Partial discharge test . 21
9.5 Test on accessories . 21
10 Sample tests on cables . 21
10.1 General . 21
10.2 Frequency of tests . 22

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IEC 63026:2019 © IEC 2019 – 3 –
10.3 Repetition of tests . 22
10.4 Conductor examination . 22
10.5 Measurement of electrical resistance of conductor and of metal screen . 22
10.6 Measurement of thickness of insulation . 23
10.6.1 General . 23
10.6.2 Requirements for the insulation . 23
10.7 Measurement of thickness of oversheath . 23
10.7.1 General . 23
10.7.2 Requirements for the oversheath . 23
10.8 Measurement of thickness of metal sheath . 23
10.8.1 General . 23
10.8.2 General . 24
10.8.3 Strip method . 24
10.8.4 Ring method . 24
10.9 Measurement of diameters . 24
10.10 Hot set test for XLPE, EPR and HEPR insulations. 24
10.10.1 Procedure . 24
10.10.2 Requirements . 24
10.11 Measurement of capacitance . 25
10.12 Tests on components of cables with a longitudinally applied metal tape or
foil, bonded to the oversheath . 25
10.13 Examination of completed cable . 25
11 Sample tests on accessories . 25
11.1 Factory joints . 25
11.1.1 General . 25
11.1.2 PD measurement and AC voltage test . 25
11.1.3 Lightning impulse voltage test . 25
11.1.4 Hot set test for insulation . 25
11.1.5 Tensile test . 26
11.1.6 Joint inspection . 26
11.1.7 Pass criteria . 26
11.2 Sample tests on repair (field) joints and terminations . 26
11.2.1 Tests on components . 26
11.2.2 Tests on complete accessory . 26
12 Type tests on cable systems . 27
12.1 General . 27
12.2 Range of type approval . 27
12.3 Summary of type tests . 29
12.4 Mechanical tests . 29
12.4.1 Coiling test . 29
12.4.2 Tensile bending test . 32
12.4.3 Tensile test . 34
12.5 Electrical type tests . 35
12.5.1 Test voltage values . 35
12.5.2 Electrical type tests and sequence of tests . 35
12.5.3 Partial discharge tests . 36
12.5.4 Tan δ measurement . 36
12.5.5 Heating cycle voltage test . 36

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– 4 – IEC 63026:2019 © IEC 2019
12.5.6 Lightning impulse voltage test followed by a power frequency voltage
test . 37
12.5.7 Examination . 37
12.5.8 Resistivity of semi-conducting screens . 38
12.6 Longitudinal/radial water penetration (LWP, RWP) test . 38
12.6.1 General . 38
12.6.2 Conductor water penetration test . 39
12.6.3 Metal screen water penetration test . 40
12.6.4 Radial water penetration test for joints . 41
12.7 Non-electrical type tests on cable components and on complete cable . 42
12.7.1 General . 42
12.7.2 Check of cable construction . 42
12.7.3 Tests for determining the mechanical properties of insulation before and
after ageing . 43
12.7.4 Tests for determining the mechanical properties of oversheaths before
and after ageing . 43
12.7.5 Ageing tests on pieces of complete cable to check compatibility of

materials . 43
12.7.6 Pressure test at high temperature for ST oversheaths. 44
7
12.7.7 Ozone resistance test for EPR and HEPR insulation . 44
12.7.8 Hot set test for EPR, HEPR and XLPE insulations . 44
12.7.9 Measurement of carbon black content of black PE oversheaths . 44
12.7.10 Tests on components of cables with a longitudinally applied metal tape
or foil, bonded to the oversheath . 45
12.7.11 Water absorption test on insulation . 45
12.7.12 Shrinkage test for XLPE insulation . 45
12.7.13 Determination of hardness of HEPR insulation . 45
12.7.14 Determination of the elastic modulus of HEPR insulation . 45
12.7.15 Shrinkage test for PE oversheath . 46
13 Electrical tests after installation . 46
13.1 General . 46
13.2 DC voltage test of the oversheath . 46
13.3 AC voltage test of the insulation . 46
13.4 DC voltage test of the insulation . 46
13.5 Time domain reflectometry (TDR) . 46
Annex A (normative) Methods of heating the test cable and determination of the cable
conductor temperature . 52
A.1 Purpose . 52
A.2 Methods of heating armoured cables for the electrical test . 52
A.2.1 Single-core cables . 52
A.2.2 Three-core cables . 53
A.3 Measurement of the temperature of the test cable. 54
A.3.1 General . 54
A.3.2 Installation of cable and temperature sensors . 54
A.4 Heating for the test . 57
Annex B (normative) Rounding of numbers . 58
Annex C (normative) Method of measuring resistivity of semi-conducting screens . 59
Annex D (normative) Tests on components of cables with a longitudinally applied
metal tape or foil, bonded to the oversheath . 62
D.1 Visual inspection . 62

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IEC 63026:2019 © IEC 2019 – 5 –
D.2 Adhesion and peel strength of metal foil . 62
D.2.1 General . 62
D.2.2 Adhesion strength test . 62
D.2.3 Peel strength test of overlapped metal foil . 63
D.2.4 Requirements for adhesion and peel strength . 65
Annex E (normative) Determination of hardness of HEPR insulations . 66
E.1 Test piece . 66
E.2 Test procedure . 66
E.2.1 General . 66
E.2.2 Surfaces of large radius of curvature . 66
E.2.3 Surfaces of small radius of curvature . 66
E.2.4 Conditioning and test temperature . 66
E.2.5 Number of measurements . 67
Annex F (informative) Tests on factory joints . 68
Annex G (normative) Tensile bending and tensile tests load calculation . 69
Annex H (informative) DC voltage test of the insulation . 70
Bibliography . 71

Figure 1 – Example of accessory length extension in the case of factory joint . 27
Figure 2 – Example of coiling test arrangement . 30
Figure 3 – Test cable length for coiling test . 31
Figure 4 – Illustration of an example of an anchoring head where relative load sharing
between conductor and armour can be controlled . 33
Figure 5 – Example of set-up for tensile bending test with a flexible or factory joint . 34
Figure 6 – Set-up for the conductor water penetration test . 40
Figure 7 – Set-up for the metal screen water penetration test . 41
Figure 8 – Circuit diagram for TDR testing (traditional transmission line diagram, π-

model) . 47
Figure A.1 – Arrangement for heating of single-core armoured cables . 52
Figure A.2 – Arrangement 1 for heating of three-core armoured cables . 53
Figure A.3 – Arrangement 2 for heating of three-core armoured cables . 54
Figure A.4 – Installation of the temperature sensors in the conductor(s) of the
reference cable . 55
Figure A.5 – Reference cable for heating of single-core armoured cables . 56
Figure A.6 – Reference cable for heating of three-core armoured cables . 57
Figure C.1 – Preparation of samples for measurement of resistivity of conductor and
insulation screens . 61
Figure D.1 – Adhesion of metal foil . 63
Figure D.2 – Example of overlapped metal foil . 63
Figure D.3 – Peel strength of overlapped metal foil . 64
Figure D.4 – Example 1 of strength versus grip spacing curve . 64
Figure D.5 – Example 2 of strength versus grip spacing curve . 65
Figure E.1 – Test on surfaces of large radius of curvature . 67
Figure E.2 – Test on surfaces of small radius of curvature . 67

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Table 1 – Recommended rated voltages U . 15
0
Table 2 – Insulating materials . 15
Table 3 – Tan δ requirements for insulating compounds for cables . 47
Table 4 – Test voltages . 47
Table 5 – Non-electrical type tests for insulating and oversheath compounds for cables . 48
Table 6 – Test requirements for mechanical characteristics of insulating compounds
for cables (before and after ageing) . 49
Table 7 – Test requirements for mechanical characteristics of oversheathing
compounds for cables (before and after ageing) . 50
Table 8 – Test requirements for particular characteristics of insulating compounds for
cables . 51
Table D.1 – Minimum acceptable adhesion or peel strength forces . 65

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IEC 63026:2019 © IEC 2019 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

SUBMARINE POWER CABLES WITH EXTRUDED INSULATION
AND THEIR ACCESSORIES FOR RATED VOLTAGES
FROM 6 kV (U = 7,2 kV) UP TO 60 kV (U = 72,5 kV) –
m m
TEST METHODS AND REQUIREMENTS

FOREWORD
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