>>
3.1 Terms and definitions
3.2 Symbols
4 Permissible current rating of cables
4.1 General
4.2 Buried cables where drying out of the soil does not occur or cables in air
4.2.1 AC cables
4.2.2 DC cables up to 5 kV
4.3 Buried cables where partial drying-out of the soil occurs
4.3.1 AC cables
4.3.2 DC cables up to 5 kV
4.4 Buried cables where drying-out of the soil shall be avoided
4.4.1 AC cables
4.4.2 DC cables up to 5 kV
4.5 Cables directly exposed to solar radiation
4.5.1 General
4.5.2 AC cables
5 Calculation of losses
5.1 AC resistance of conductor
5.1.1 General
5.1.2 DC resistance of conductor
5.1.3 Skin effect factor ys
5.1.4 Proximity effect factor yp for two-core cables and for two single-core cables
5.1.5 Proximity effect factor yp for three-core cables and for three single-core cables
5.1.6 Skin and proximity effects in pipe-type cables
5.2 Dielectric losses (applicable to AC cables only)
5.3 Loss factor for sheath and screen (applicable to power frequency AC cables only)
5.3.1 General
5.3.2 Two single-core cables, and three single-core cables (in trefoil formation), sheaths bonded at both ends of an electrical section
5.3.3 Three single-core cables in flat formation, with regular transposition, sheaths bonded at both ends of an electrical section
5.3.4 Three single-core cables in flat formation, without transposition, sheaths bonded at both ends of an electrical section
5.3.5 Variation of spacing of single-core cables between sheath bonding points
5.3.6 Effect of Milliken conductors
5.3.7 Single-core cables, with sheaths bonded at a single point or cross-bonded
5.3.8 Two-core unarmoured cables with common sheath
5.3.9 Three-core unarmoured cables with common sheath
5.3.10 Two-core and three-core cables with steel tape armour
5.3.11 Cables with each core in a separate metallic sheath (SL type) and armoured
5.3.12 Losses in screen and sheaths of pipe-type cables
5.4 Loss factor for armour, reinforcement and steel pipes (applicable to power frequency AC cables only)
5.4.1 General
5.4.2 Non-magnetic armour or reinforcement
5.4.3 Magnetic armour or reinforcement
5.4.4 Losses in steel pipes
Annex A (normative) Correction factor for increased lengths of individual cores within multicore cables
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GSO IEC 60287-1-1:2025
IEC 60287-1-1:2023
مواصفة قياسية خليجية
الكابلات الكهربائية-حساب مقنن التيار- جزء 1-1: معادلات تقنين التيار (معامل الحمل 100 ٪) وحساب المفاقيد - عام
Gulf Standard
Electric cables - Calculation of the current rating - Part 1-1: Current rating equations (100 % load factor) and calculation of losses - General
ICS: |
29.060.20
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© GCC Standardization Organization 2025 – All rights reserved
© هيئة التقييس لدول مجلس التعاون لدول الخليج العربية 2025 – جميع الحقوق محفوظة
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جميع الحقوق محفوظة لهيئة لتقييس لدول مجلس التعاون لدول الخليج العربية.
ما لم ينص على خلاف ذلك، لا يجوز إعادة إنتاج أي جزء من هذا المنشور أو استخدامه بأي شكل آخر أو بأي وسيلة، إلكترونية أو ميكانيكية، بما في ذلك التصوير، أو النشر على الإنترنت أو الإنترانت، دون إذن كتابي مسبق من هيئة التقييس لدول مجلس التعاون لدول الخليج العربية على العنوان أدناه أو الدول الأعضاء في الهيئة داخل بلدانهم.
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All rights reserved to GCC Standardization Organization (GSO). Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either GSO at the address below or GSO's member body in the country of the requester.
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Outreach Dept, Knowledge Management Section
GCC Standardization Organization (GSO)
P.O.Box: 85245 Riyadh 12511
Kingdom of Saudi Arabia
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إدارة التواصل، قسم إدارة المعرفة
هيئة التقييس لدول مجلس التعاون لدول الخليج العربية (GSO)
ص. ب: 85245 الرياض 12511
المملكة العربية السعودية
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Gulf Foreword
GCC Standardization Organization (GSO) is a regional organization which consists of the national standardization bodies of GCC member states. One of GSO main functions is to issue gulf standards and technical regulations through specialized technical committees.
GSO Technical Council
in its meeting number (60) held
on 23/10/1446 H,
which corresponds to 22/04/2025, has approved
the update of
Gulf
Standard
GSO IEC 60287-1-1:2025
titled "Electric cables - Calculation of the current rating - Part 1-1: Current rating equations (100 % load factor) and calculation of losses - General" in
English
language
which was studied
and adopted
from
International Electrotechnical Commission
Standard
IEC 60287-1-1:2023
without any technical modifications
through
the technical program of
GSO Technical Committee for Electric Power Generation, Transmission and Distribution Equipment
(TC09)
in YEMEN schedule
.
This document will cancel and replace the Gulf
Standard
GSO IEC 60287-1-1:2014.
| تقديم خليجي |
هيئة التقييس لدول مجلس التعاون لدول الخليج العربية هيئة إقليمية تضم في عضويتها أجهزة التقييس الوطنية في الدول الأعضاء ، ومن مهام الهيئة إعداد المواصفات القياسية واللوائح الفنية الخليجية بواسطة لجان فنية متخصصة.
قرر المجلس الفني
لهيئة التقييس لدول مجلس التعاون لدول الخليج العربية
في الاجتماع الـ (60)
بتاريخ 1446/10/23 هـ ،الموافق 2025/04/22م اعتماد
تحديث
المواصفة القياسية الخليجية
رقم GSO IEC 60287-1-1:2025
وعنوانها "الكابلات الكهربائية-حساب مقنن التيار- جزء 1-1: معادلات تقنين التيار (معامل الحمل 100 ٪) وحساب المفاقيد - عام"
باللغة
الانجليزية
التي تم دراستها
وتبنيها
عن
اللجنة الدولية الكهروتقنية
رقم
IEC 60287-1-1:2023
بدون إدخال تعديلات فنية عليها
ضمن برنامج عمل
اللجنة الفنية الخليجية لمواصفات معدات توليد ونقل وتوزيع الطاقة الكهربائية
(TC09)
المدرجة في خطة الجمهورية اليمنية
.
على أن تلغي وتحل محل
المواصفة القياسية
رقم
GSO IEC 60287-1-1:2014
.
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Gulf StandardGSO IEC 60287-1-1:2025
Gulf StandardGSO IEC 60287-1-1:2025
Gulf StandardGSO IEC 60287-1-1:2025
GSO IEC 60287-1-1:2025Gulf Standard
| IEC 60287-1-1 |
INTERNATIONAL STANDARD | Edition 3.0 2023-05 | |
| Electric cables – Calculation of the current rating – Part 1-1: Current rating equations (100 % load factor) and calculation of losses – General | ||
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Gulf StandardGSO IEC 60287-1-1:2025
Gulf StandardGSO IEC 60287-1-1:2025
GSO IEC 60287-1-1:2025Gulf Standard
 | THIS PUBLICATION IS COPYRIGHT PROTECTEDCopyright © 2023 IEC, Geneva, Switzerland |
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Gulf StandardGSO IEC 60287-1-1:2025
Gulf StandardGSO IEC 60287-1-1:2025
Gulf StandardGSO IEC 60287-1-1:2025
GSO IEC 60287-1-1:2025Gulf Standard
| IEC 60287-1-1 |
INTERNATIONAL STANDARD | Edition 3.0 2023-05 | |
| Electric cables – Calculation of the current rating – Part 1-1: Current rating equations (100 % load factor) and calculation of losses – General | ||
INTERNATIONAL
ELECTROTECHNCIAL
COMMISSION
ICS 29.060.20ISBN 9782832269374Warning! Make sure that you obtained this publication from an authorized distributor.© Registered trademark of the International Electrotechnical Commission
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GSO IEC 60287-1-1:2025Gulf Standard
CONTENTS
4 Permissible current rating of cables
4.1 General
4.2 Buried cables where drying out of the soil does not occur or cables in air
4.2.1 AC cables
4.2.2 DC cables up to 5 kV
4.3 Buried cables where partial drying-out of the soil occurs
4.3.1 AC cables
4.3.2 DC cables up to 5 kV
4.4 Buried cables where drying-out of the soil shall be avoided
4.4.1 AC cables
4.4.2 DC cables up to 5 kV
4.5 Cables directly exposed to solar radiation
4.5.1 General
4.5.2 AC cables
5 Calculation of losses
5.1 AC resistance of conductor
5.1.1 General
5.1.2 DC resistance of conductor
5.1.3 Skin effect factor ys
5.1.4 Proximity effect factor yp for two-core cables and for two single-core cables
5.1.5 Proximity effect factor yp for three-core cables and for three single-core cables
5.1.6 Skin and proximity effects in pipe-type cables
5.2 Dielectric losses (applicable to AC cables only)
5.3 Loss factor for sheath and screen (applicable to power frequency AC cables only)
5.3.1 General
5.3.2 Two single-core cables, and three single-core cables (in trefoil formation), sheaths bonded at both ends of an electrical section
5.3.3 Three single-core cables in flat formation, with regular transposition, sheaths bonded at both ends of an electrical section
5.3.4 Three single-core cables in flat formation, without transposition, sheaths bonded at both ends of an electrical section
5.3.5 Variation of spacing of single-core cables between sheath bonding points
5.3.6 Effect of Milliken conductors
5.3.7 Single-core cables, with sheaths bonded at a single point or cross-bonded
5.3.8 Two-core unarmoured cables with common sheath
5.3.9 Three-core unarmoured cables with common sheath
5.3.10 Two-core and three-core cables with steel tape armour
5.3.11 Cables with each core in a separate metallic sheath (SL type) and armoured
5.3.12 Losses in screen and sheaths of pipe-type cables
5.4 Loss factor for armour, reinforcement and steel pipes (applicable to power frequency AC cables only)
5.4.1 General
5.4.2 Non-magnetic armour or reinforcement
5.4.3 Magnetic armour or reinforcement
5.4.4 Losses in steel pipes
Annex A (normative) Correction factor for increased lengths of individual cores within multicore cables
Electric cables - Calculation of the current rating - Part 1-1: Current rating equations (100 % load factor) and calculation of losses - General
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.
IEC 60287-1-1 has been prepared by IEC technical committee 20: Electric cables. It is an International Standard.
This third edition cancels and replaces the second edition published in 2006 and Amendment 1:2014. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a)
thorough redefinition of symbols used across the IEC 60287 and IEC 60853 series to realign and unify definitions, eliminate inconsistencies and to improve cross-use of the different parts of both IEC 60287 and IEC 60853 series;
b)
introduction of corrective factors on relevant calculated physical characteristics to take into account the effect of multicore lay-lengths; a dedicated annex to highlight correction factors for different number of cores has been introduced (Annex A).
The text of this International Standard is based on the following documents:
| Draft | Report on voting |
|---|---|
| 20/2096/FDIS | 20/2103/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 60287 series, published under the general title Electric cables - Calculation of the current rating, 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,
•
replaced by a revised edition, or
•
amended.
INTRODUCTION
This part of IEC 60287 contains formulae for the quantities RC, Wd, λ1 and λ2.
It contains methods for calculating the permissible current rating of cables from details of the permissible temperature rise, conductor resistance, losses and thermal resistivities.
Formulae for the calculation of losses are also given.
The formulae in this document contain quantities which vary with cable design and materials used. The values given in the tables are either internationally agreed, for example, electrical resistivities and resistance temperature coefficients, or are those which are generally accepted in practice, for example, thermal resistivities and permittivities of materials. In this latter category, some of the values given are not characteristic of the quality of new cables but are considered to apply to cables after a long period of use. In order that uniform and comparable results can be obtained, the current ratings should be calculated with the values given in this document. However, where it is known with certainty that other values are more appropriate to the materials and design, then these may be used, and the corresponding current rating declared in addition, provided that the different values are quoted.
Quantities related to the operating conditions of cables are liable to vary considerably from one country to another. For instance, with respect to the ambient temperature and soil thermal resistivity, the values are governed in various countries by different considerations. Superficial comparisons between the values used in the various countries can lead to erroneous conclusions if they are not based on common criteria: for example, there can be different expectations for the life of the cables, and in some countries design is based on maximum values of soil thermal resistivity, whereas in others average values are used. Particularly, in the case of soil thermal resistivity, it is well known that this quantity is very sensitive to soil moisture content and can vary significantly with time, depending on the soil type, the topographical and meteorological conditions, and the cable loading.
The following procedure for choosing the values for the various parameters should, therefore, be adopted.
Numerical values should preferably be based on results of suitable measurements. Often such results are already included in national specifications as recommended values, so that the calculation can be based on these values generally used in the country in question; a survey of such values is given in IEC 60287-3-1.
A suggested list of the information required to select the appropriate type of cable is given in IEC 60287-3-1.
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1Scope
This part of IEC 60287 is applicable to the conditions of steady-state operation of cables at all alternating voltages, and direct voltages up to 5 kV, buried directly in the ground, in ducts, troughs or in steel pipes, both with and without partial drying-out of the soil, as well as cables in air. The term "steady state" is intended to mean a continuous constant current (100 % load factor) just sufficient to produce asymptotically the maximum conductor temperature, the surrounding ambient conditions being assumed constant.
This document provides formulae for current ratings and losses.
The formulae given are essentially literal and designedly leave open the selection of certain important parameters. These can be divided into three groups:
-
parameters related to construction of a cable (for example, thermal resistivity of insulating material) for which representative values have been selected based on published work;
-
parameters related to the surrounding conditions, which can vary widely, the selection of which depends on the country in which the cables are used or will be used;
-
parameters which result from an agreement between manufacturer and user and which involve a margin for security of service (for example, maximum conductor temperature).
2Normative 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 60228, Conductors of insulated cables
IEC 60287-1-3, Electric cables - Calculation of the current rating - Part 1-3: Current rating equations (100 % load factor) and calculation of losses - Current sharing between parallel single-core cables and calculation of circulating current losses
IEC 60287-2-1:2023, Electric cables - Calculation of the current rating - Part 2-1: Thermal resistance - Calculation of the thermal resistance
3Terms, definitions and symbols
3.1Terms 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
3.2Symbols
The symbols used in this document and the quantities which they represent are given in the following list.
AA | cross-sectional area of the armour mm2 | ||
B1, B2 | coefficients (see 5.4.3) Ω/m | ||
C | capacitance per core F/m | ||
CF | coefficient defined in 5.3.6 | ||
CfL | coefficient to take into account the position of the neutral axis of the helically wound core in Annex A | ||
Cgs | coefficient used in 5.3.7.1 | ||
CLL | length correction factor for considering laying up of cores | ||
CM1 | coefficient defined in 5.3.6 | ||
CN | coefficient defined in 5.3.6 | ||
CP | coefficient defined in 5.3.4 Ω/m | ||
Cp | coefficient used in 5.3.7.2 | ||
CQ | coefficient defined in 5.3.4 Ω/m | ||
Cq | coefficient used in 5.3.7.2 | ||
De* | external diameter of cable m | ||
Di | diameter over insulation mm | ||
Dp* | diameter over the individual core of a multicore cable m | ||
Ds | external diameter of metal sheath mm | ||
Doc | diameter of the imaginary coaxial cylinder which just touches the crests of a corrugated sheath mm | ||
Dit | diameter of the imaginary cylinder which just touches the inside surface of the troughs of a corrugated sheath mm | ||
Ee | intensity of solar radiation W/m2 | ||
H | magnetizing force (see 5.4.3) A/m | ||
Hs | inductance of sheath H/m | ||
H1, H2, H3 | components of inductance due to the steel wires (see 5.4.3) H/m | ||
I | current in one conductor (RMS value) A | ||
IS | current in sheath (RMS value) A | ||
| axial cable length over which the cores make one full helical turn m | ||
RC | alternating current resistance of conductor at its maximum operating temperature per unit length of the cable Ω/m | ||
RA | AC resistance of armour at its maximum operating temperature per unit length of the cable Ω/m | ||
RAo | AC resistance of armour at 20 °C per unit length of the cable Ω/m | ||
Re | equivalent AC resistance of sheath and armour in parallel Ω/m | ||
Rs | AC resistance of cable sheath or screen at their maximum operating temperature per unit length of the cable Ω/m | ||
Rso | AC resistance of cable sheath or screen at 20 °C per unit length of the cable Ω/m | ||
R′ | DC resistance of conductor at maximum operating temperature per unit length of the cable Ω/m | ||
Ro | DC resistance of conductor at 20 °C per unit length of the cable Ω/m | ||
T1 | thermal resistance per core between conductor and sheath per unit length of the cable K · m/W | ||
T2 | thermal resistance between sheath and armour per unit length of the cable K · m/W | ||
T3 | thermal resistance of external serving per unit length of the cable K · m/W | ||
T4 | thermal resistance of surrounding medium (ratio of cable surface temperature rise above ambient to the losses per unit length) K · m/W | ||
T#4 | thermal resistance in free air, adjusted for solar radiation K · m/W | ||
| thermal resistance between cable and duct (or pipe) K · m/W | ||
| thermal resistance of the duct (or pipe) K · m/W | ||
| thermal resistance of the medium surrounding the duct (or pipe) K · m/W | ||
Uo | voltage between conductor and screen or sheath V | ||
WA | losses in armour per unit length of the cable W/m | ||
Wc | losses in conductor per unit length of the cable W/m | ||
Wd | dielectric losses per unit length of the cable per phase W/m | ||
Ws | losses dissipated in sheath per unit length of the cable W/m | ||
W(s+A) | total losses in sheath and armour per unit length of the cable W/m | ||
X | reactance of sheath (two-core cables and three-core cables in trefoil) per unit length of the cable Ω/m | ||
X1 | reactance of sheath (cables in flat formation) Ω/m | ||
Xm | mutual reactance between the sheath of one cable and the conductors of the other two when cables are in flat information Ω/m | ||
a | shortest minor length in a cross-bonded electrical section having unequal minor lengths m | ||
c | distance between the axes of conductors and the axis of the cable for three-core cables mm | ||
d | mean diameter of sheath or screen mm | ||
d′ | mean diameter of sheath and reinforcement mm | ||
d2 | mean diameter of reinforcement mm | ||
dA | mean diameter of armour mm | ||
dc | external diameter of conductor mm | ||
d′c | external diameter of equivalent round solid conductor having the same central duct as a hollow conductor mm | ||
dd | internal diameter of pipe mm | ||
df | diameter of a steel wire mm | ||
di | internal diameter of hollow conductor mm | ||
dM | major diameter of screen or sheath of an oval conductor mm | ||
dm | minor diameter of screen or sheath of an oval conductor mm | ||
dx | diameter of an equivalent circular conductor having the same cross-sectional area and degree of compactness as the shaped one mm | ||
f | system frequency Hz | ||
kf | factor used in the calculation of hysteresis losses in armour or reinforcement (see 5.4.3.4) | ||
kp | factor used in calculating xp (proximity effect) | ||
ks | factor used in calculating xs (skin effect) | ||
l* | length of a cable section (general symbol, see 5.3.5) m | ||
ln | natural logarithm (logarithm to base e, see IEC 60027-3) | ||
m | parameter used in calculation of eddy-current loss factor 10−7 m/Ω | ||
n | number of conductors in a cable | ||
n1 | number of steel wires in a cable (see 5.4.3) | ||
p | length of lay of a steel wire along a cable (see 5.4.3) | ||
r1 | circumscribing radius of two- or three-sector shaped conductors mm | ||
s | axial separation of conductors mm | ||
s1 | axial separation of two adjacent cables in a horizontal group of three, not touching mm | ||
s2 | axial spacing between adjacent cables in trefoil formation; for cables in flat formation s2 is the geometric mean of the three spacings mm | ||
t0 | insulation thickness between conductors mm | ||
t3 | thickness of the serving mm | ||
ts | thickness of the sheath mm | ||
v | ratio of the thermal resistivities of dry and moist soils (v = ρd/ρw) | ||
xp | argument of a Bessel function used to calculate proximity effect | ||
xs | argument of a Bessel function used to calculate skin effect | ||
yp | proximity effect factor (see 5.1) | ||
ys | skin effect factor (see 5.1) | ||
α20 | temperature coefficient of electrical resistivity at 20 °C, per kelvin I/K | ||
β1 | coefficient used in 5.3.7.1 | ||
β2 | angle between axis of armour wires and axis of cable (see 5.4.3) | ||
γ | angular time delay (see 5.4.3) | ||
Δ1, Δ2 | coefficients used in 5.3.7.1 | ||
δA | equivalent thickness of armour or reinforcement mm | ||
tanδ | loss factor of insulation | ||
ε | relative permittivity of insulation | ||
ε0 | permittivity of vacuum F/m | ||
θ | maximum operating temperature of conductor °C | ||
θa | ambient temperature °C | ||
θar | maximum operating temperature of armour °C | ||
θsc | maximum operating temperature of cable screen or sheath °C | ||
θx | critical temperature of soil; this is the temperature of the boundary between dry and moist zones °C | ||
Δθ | permissible temperature rise of conductor above ambient temperature K | ||
Δθx | critical temperature rise of soil; this is the temperature rise of the boundary between dry and moist zones above the ambient temperature of the soil K | ||
λ0 | coefficient used in 5.3.7.1 | ||
λ1, λ2 | ratio of the total losses in metallic sheaths and armour respectively to the total conductor losses (or losses in one sheath or armour to the losses in one conductor) | ||
| ratio of the losses in one sheath caused by circulating currents in the sheath to the losses in one conductor | ||
| ratio of the losses in one sheath caused by eddy currents to the losses in one conductor | ||
| loss factor for the middle cable of three cables in flat formation without transposition, with sheaths bonded at both ends | ||
| loss factor for the outer cable with the greater losses of three cables in flat formation without transposition, with sheaths bonded at both ends | ||
| loss factor for the outer cable with the least losses of three cables in flat formation without transposition, with sheaths bonded at both ends | ||
µ | relative magnetic permeability of armour material | ||
µe | longitudinal relative permeability | ||
µt | transverse relative permeability | ||
ρ20 | conductor resistivity at 20 °C Ω · m | ||
ρd | thermal resistivity of dry soil K · m/W | ||
ρw | thermal resistivity of moist soil K · m/W | ||
ρs | sheath resistivity at 20 °C Ω · m | ||
σ | absorption coefficient of solar radiation for the cable surface | ||
ω | angular frequency of system (2πf) |
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Gulf StandardGSO IEC 60287-1-1:2025
Gulf StandardGSO IEC 60287-1-1:2025
Gulf StandardGSO IEC 60287-1-1:2025
GSO IEC 60287-1-1:2025Gulf Standard
Bibliography
IEC 60027-3, Letter symbols to be used in electrical technology - Part 3: Logarithmic and related quantities, and their units
IEC 60028:1925, International standard of resistance for copper
IEC 60141 (all parts), Tests on oil-filled and gas-pressure cables and their accessories
IEC 60502-1, Power cables with extruded insulation and their accessories for rated voltages from 1 kV (Um = 1,2 kV) up to 30 kV (Um = 36 kV) - Part 1: Cables for rated voltages of 1 kV (Um = 1,2 kV) and 3 kV (Um = 3,6 kV)
IEC 60502-2, Power cables with extruded insulation and their accessories for rated voltages from 1 kV (Um = 1,2 kV) up to 30 kV (Um = 36 kV) - Part 2: Cables for rated voltages from 6 kV (Um = 7,2 kV) up to 30 kV (Um = 36 kV)
IEC 60853 (all parts), Calculation of the cyclic and emergency current rating of cables
IEC 60889, Hard-drawn aluminium wire for overhead line conductors
Electra No. 104, Part 1, "Current ratings of cables buried in partially dried-out soil", p.11, January 1966
CIGRE TB 272, Large cross-sections and composite screens design
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