SIST EN 61238-1:2004

SLOVENSKI STANDARD
01-januar-2004
Stisljivi in vijačni konektorji za električne kable za naznačene napetosti do 36 kV
(Um = 42 kV) - 1. del: Preskusne metode in zahteve
Compression and mechanical connectors for power cables for rated voltages up to 36 kV
(Um = 42 kV) - Part 1: Test methods and requirements
Pressverbinder und Schraubverbinder für Starkstromkabel für Nennspannungen bis
einschließlich 36 kV (Um = 42 kV) -- Teil 1: Prüfverfahren und Anforderungen
Raccords sertis et à serrage mécanique pour câbles d'énergie de tensions assignées
inférieures ou égales à 36 kV (Um = 42 kV) -- Partie 1: Méthodes et prescriptions
d'essais
Ta slovenski standard je istoveten z: EN 61238-1:2003
ICS:
29.060.20 Kabli Cables
29.120.20 Spojni elementi Connecting devices
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 61238-1
NORME EUROPÉENNE
EUROPÄISCHE NORM August 2003
ICS 29.060.20
English version
Compression and mechanical connectors for power cables
for rated voltages up to 36 kV (U = 42 kV)
m
Part 1: Test methods and requirements
(IEC 61238-1:2003, modified)
Raccords sertis et à serrage mécanique Pressverbinder und Schraubverbinder
pour câbles d'énergie de tensions für Starkstromkabel für Nennspannungen
assignées inférieures ou égales bis einschließlich 36 kV (U = 42 kV)
m
à 36 kV (U = 42 kV) Teil 1: Prüfverfahren und Anforderungen
m
Partie 1: Méthodes et prescriptions (IEC 61238-1:2003, modifiziert)
d'essais
(CEI 61238-1:2003, modifiée)
This European Standard was approved by CENELEC on 2003-06-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and
notified to the Central Secretariat has the same status as the official versions.

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

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

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

© 2003 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61238-1:2003 E
Foreword
The text of document 20/599/FDIS, future edition 2 of IEC 61238-1, prepared by IEC TC 20, Electric
cables, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 61238-1 on 2003-06-01.
A draft amendment, prepared by the Technical Committee CENELEC TC 20, Electric cables, was
submitted to the formal vote and was approved by CENELEC for inclusion into EN 61238-1 on
2003-06-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2004-03-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2006-06-01
Annexes designated "normative" are part of the body of the standard.
Annexes designated "informative" are given for information only.
In this standard, annexes A, B, E and ZA are normative and annexes C, D, F, G and H are informative.
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 61238-1:2003 was approved by CENELEC as a European
Standard with agreed common modifications as given below.

COMMON MODIFICATIONS
Title
Amend the title to show the following upper voltage limit:

“………….for rated voltages up to 36 kV (U = 42 kV)”
m
Introduction
Amend the end of the first sentence of paragraph 1 to read:

“………….for rated voltages up to 36 kV (U = 42 kV)”
m
Scope and object
Amend the voltage reference in paragraph 1 to read:

“………….for rated voltages up to 36 kV (U = 42 kV),………….”
m
In the Bibliography, add the following note for the standard indicated:
IEC 60694 NOTE  Harmonized as EN 60694:1996 (not modified).
__________
– 3 – EN 61238-1:2003
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other publications.
These normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this European Standard only when incorporated in it by amendment or revision. For undated
references the latest edition of the publication referred to applies (including amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.
Publication Year Title EN/HD Year
IEC 60050-461 1984 International Electrotechnical - -
Vocabulary (IEV)
Chapter 461: Electric cables
A1 1993 - -
IEC 60228 (mod) 1978 Conductors of insulated cables
+ IEC 60228A 1982 First supplement: Guide to the HD 383 S2 1986
(mod) dimensional limits of circular conductors

IEC 60493-1 1974 Guide for the statistical analysis of - -
ageing test data
Part 1: Methods based on mean values
of normally distributed test results

NORME CEI
INTERNATIONALE IEC
61238-1
INTERNATIONAL
Deuxième édition
STANDARD
Second edition
2003-05
Raccords sertis et à serrage mécanique
pour câbles d'énergie de tensions assignées
inférieures ou égales à 30 kV (U = 36 kV) –
m
Partie 1:
Méthodes et prescriptions d'essais
Compression and mechanical connectors
for power cables for rated voltages
up to 30 kV (U = 36 kV) –
m
Part 1:
Test methods and requirements
 IEC 2003 Droits de reproduction réservés  Copyright - all rights reserved
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électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from
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Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch  Web: www.iec.ch
CODE PRIX
XA
Commission Electrotechnique Internationale PRICE CODE
International Electrotechnical Commission
Международная Электротехническая Комиссия
Pour prix, voir catalogue en vigueur
For price, see current catalogue

61238-1  IEC:2003 – 3 –
CONTENTS
FOREWORD . 7
INTRODUCTION .11
1 Scope and object .13
2 Normative references.15
3 Definitions.15
4 Symbols.19
5 General.21
5.1 Conductor.21
5.2 Connectors and tooling .21
5.3 Range of approval.21
6 Electrical tests .23
6.1 Installation .23
6.2 Measurements .25
6.3 Heat cycle test .27
6.4 Assessment of results.33
6.5 Requirements .35
7 Mechanical tests .35
7.1 Method .35
7.2 Requirements .35
8 Test report .37

Annex A (normative) Equalizers and their preparation .51
Annex B (normative) Measurements .55
Annex C (informative) Recommendations to improve accuracy of measurement.57
Annex D (informative) Determination of the value of the short-circuit-current.59
Annex E (normative) Calculation method .61
Annex F (informative) Explanation of the calculation method.71
Annex G (informative) Explanation of the temperature profile .105
Annex H (informative) Explanation of the statistical method of assessing results of tests
on electrical connectors.109
Figure 1 – Typical test circuit for through connectors and terminal lugs .39
Figure 2 – Typical test circuit for branch connectors.41
Figure 3 – Typical cases of resistance measurements .47
Figure 4 – Second heat cycle.49
Figure A.1 – Preparation of equalizers .53
Figure E.1 – Graphic example of assessment of an individual connector for Class A .65
Figure F.1 – Plot of connector resistance factors and parameter δ before heat cycle 1 .81
k
ij
Figure F.2 – Plot of resistance factors k , estimated mean resistance factors  and
i.
k
estimated overall mean .85

61238-1  IEC:2003 – 5 –
k
Figure F.3 – Plot of estimated mean resistance factors k , estimated overall mean
i.
and parameter β .87
Figure F.4 – Typical ageing behaviour of an electrical connector (k limiting resistance
lim
factor; t lifetime).89
L
Figure F.5 – Plot of the resistance factors, fitted values, estimated intercept and
estimated slope .91
i
Figure F.6 – Plot of the fitted values, residuals and parameter M .93
Figure F.7 – Plot of the pointwise 90 % confidence interval for the mean response and
i
parameter S .97
i i i
Figure F.8 – Plot of parameters M , S and D with regression line .99
Table 1 – Minimum elevated current heating time .31
Table 2 – Electrical test requirements .35
Table 3 – Tensile force for mechanical tests .35
Table A.1 – Equalizer dimensions .51
Table F.1 – Indices.71
Table F.2 – Measured variables.71
Table F.3 – Constants .71
Table F.4 – Calculated variables.73
Table F.5 – Repeatedly measured parameters .75
ij
Table F.6 – Number of calculated connector resistance factors k for Class A
connectors .77
ij
Table F.7 – Connector resistance factors k for Class A connectors related to the
dummy variable x, the initial scatter δ and the mean scatter β .83
Table F.8 – Number of resistance factor ratios for connectors of Class A .101
Table F.9 – Recorded maximum temperatures during heat cycling .103
Table H.1 – Summary of requirements.113

61238-1  IEC:2003 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
COMPRESSION AND MECHANICAL CONNECTORS
FOR POWER CABLES FOR RATED VOLTAGES
UP TO 30 kV (U = 36 kV) –
m
Part 1: Test methods and requirements
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61238-1 has been prepared by IEC technical committee 20: Electric
cables.
This second edition cancels and replaces the first edition published in 1993 and constitutes
a technical revision.
Significant technical changes with respect to the previous edition are as follows:
a) The scope is now restricted to connectors to be used on power cables for rated voltages up
to 30 kV (U = 36 kV);
m
b) The concept of direct measurement of resistance has been introduced as an alternative to
the indirect measurement, with associated tolerances;
c) Temperature limits have been given for insulation piercing connectors, depending on the
type of cable insulation;
d) For short-circuit tests, tolerances have been given on the duration and recommendations
have been given for large cross-sections;
e) Some approval criteria have been revised and harmonized between mechanical connectors
and compression connectors;
f) The information to be included in the test report has been added;
g) Informative annexes have been added, with information on measuring accuracy, the calcul-
ation method, the temperature profile and the statistical method.

61238-1  IEC:2003 – 9 –
The text of this standard is based on the following documents:
FDIS Report on voting
20/599/FDIS 20/632/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 2012.
At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
61238-1  IEC:2003 – 11 –
INTRODUCTION
This part of IEC 61238 deals with type tests for compression and mechanical connectors for
use on copper or aluminium conductors of power cables for rated voltages up to 30 kV
(U = 36 kV). When a design of connector meets the requirements of this standard, then it is
m
expected that in service:
a) the resistance of the connection will remain stable;
b) the temperature of the connector will be of the same order or less than that of the
conductor;
c) the mechanical strength will be fit for the purpose;
d) if the intended use demands it, application of short-circuit currents will not affect a) and b).
It should be stressed that, although the electrical and mechanical tests specified in this
standard are to prove the suitability of connectors for most operating conditions, they do not
necessarily apply to situations where a connector may be raised to a high temperature by virtue
of connection to highly rated plant, or where the connector is subjected to excessive
mechanical vibration or shock or to corrosive conditions. In these instances, the tests in
this standard may need to be supplemented by special tests agreed between supplier and
purchaser.
61238-1  IEC:2003 – 13 –
COMPRESSION AND MECHANICAL CONNECTORS
FOR POWER CABLES FOR RATED VOLTAGES
UP TO 30 kV (U = 36 kV) –
m
Part 1: Test methods and requirements
1 Scope and object
This part of IEC 61238 applies to compression and mechanical connectors for power cables for
rated voltages up to 30 kV (U = 36 kV), e.g. buried cables or cables installed in buildings,
m
having
a) conductors complying with IEC 60228 and IEC 60228A with cross-sectional areas 10 mm
and greater for copper and 16 mm and greater for aluminium,
b) a maximum continuous conductor temperature not exceeding 90 °C.
This standard is not applicable to connectors for overhead conductors, which are designed for
special mechanical requirements, or to separable connectors with a sliding contact or multi-
core connectors (i.e. ring connectors).
Although it is not possible to define precisely the service conditions for all applications, two
broad classes of connectors have been identified.
Class A
These are connectors intended for electricity distribution or industrial networks in which they
can be subjected to short-circuits of relatively high intensity and duration. As a consequence,
Class A connectors are suitable for the majority of applications.
Class B
These are connectors for networks in which overloads or short-circuits are rapidly cleared by
the installed protective devices, e.g. fast-acting fuses.
Depending on the application, the connectors are subjected to the following tests:
Class A: heat cycle and short-circuit tests;
Class B: heat cycle tests only.
The object of this standard is to define the type test methods and requirements, which apply
to compression and mechanical connectors for power cables with copper or aluminium
conductors.
Formerly, approval for such products has been achieved on the basis of national standards and
specifications and/or the demonstration of satisfactory service performance. The publication of
this IEC standard does not invalidate existing approvals. However, products approved
according to these earlier standards or specifications cannot claim approval to this IEC
standard unless specifically tested to it.

61238-1  IEC:2003 – 15 –
After they have been made, these tests need not be repeated unless changes are made in the
connector material, design or manufacturing process which might affect the performance
characteristics.
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
IEC 60050(461):1984, International Electrotechnical Vocabulary (IEV) – Chapter 461: Electric
cables
Amendment 1 (1993)
IEC 60228:1978, Conductors of insulated cables
IEC 60228A:1982, First supplement – Conductors of insulated cables – Guide to the dimen-
sional limits of circular conductors
IEC 60493-1:1974, Guide for the statistical analysis of ageing test data – Part 1: Methods
based on mean values of normally distributed test results
3 Definitions
For the purposes of part of IEC 61238, the following definitions apply. Where possible, the
definitions used are in accordance with IEC 60050(461).
3.1
connector (of cables)
metallic device for connecting a conductor to an equipment terminal or for connecting two or
more conductors to each other
[IEV 461-17-03, modified]
3.2
through connector
metallic device for connecting two consecutive lengths of conductor
[IEV 461-17-04]
3.3
branch connector
metallic device for connecting a branch conductor to a main conductor at an intermediate point
on the latter
[IEV 461-17-05]
3.4
(terminal) lug
metallic device to connect a cable conductor to other electrical equipment
[IEV 461-17-01]
61238-1  IEC:2003 – 17 –
3.5
palm (of terminal lug)
part of a terminal lug used to make the connection to electrical equipment
[IEV 461-17-07]
3.6
barrel (of terminal lug, of connector, etc.)
part of a device into which the conductor to be connected is introduced
[IEV 461-17-06]
3.7
reference conductor
length of unjointed bare conductor or conductor with the insulation removed, which is included
in the test loop and which enables the reference temperature and reference resistance to be
determined
3.8
equalizer
arrangement used in the test loop to ensure a point of equipotential in a stranded conductor
3.9
compression jointing
method of securing a connector to a conductor by using a special tool to produce permanent
deformation of the connector and the conductor
3.10
mechanical jointing
method of securing a connector to a conductor, for example by means of a bolt or screw acting
on the latter or by alternative methods
3.11
median connector
connector which during the first heat cycle records the third highest temperature of the six
connectors in the test loop
3.12
insulation piercing connector (IPC)
connector in which electrical contact with the conductor is made by metallic protrusions which
pierce the insulation of the cable core
[IEV 461-11-08]
NOTE The abbreviation IPC will be used throughout the standard.

61238-1  IEC:2003 – 19 –
4 Symbols
A nominal cross-sectional area of the conductor
D change in the resistance factor of the connector
I direct current flowing through a connection during resistance measurement
I equivalent r.m.s. short-circuit current
rms
I alternating current necessary to maintain the reference conductor at its equilibrium
N
temperature
I direct current flowing through the reference conductor/conductors during resistance
r
measurement
k connector resistance factor: ratio of the resistance of a connector to that of the
resistance of the equivalent length of the reference conductor
l , l , l lengths of the connector assembly associated with the measurement points after
a b j
jointing
l length of the reference conductor between measurement points
r
t heating time
t time necessary for the connectors and the reference conductor to cool to a value
equal to or less than 35 °C
U potential difference between measurement points when current I is flowing
U potential difference between measuring points on a reference conductor when current
r
I is flowing
r
α temperature coefficient of resistance at 20 °C
β mean scatter of the connector resistance factors
δ initial scatter of the connector resistance factors
λ resistance factor ratio: change in the resistance factor of the connector, relative to its
initial resistance factor
θ temperature of a connector
θ maximum temperature recorded on a connector over the total period of test
max
θ temperature of the reference conductor determined in the first heat cycle
R
θ temperature of the reference conductor at the moment of measuring θ
ref max
NOTE Suffixes may be used to indicate values for the individual connector, see Annex F.

61238-1  IEC:2003 – 21 –
5 General
5.1 Conductor
The following information shall be recorded in the test report:
– conductor material;
– nominal cross-sectional area, dimensions and shape. It is recommended that the actual
cross-sectional area should also be given;
– type of conductor, i.e. solid or stranded. In the case of stranded conductors, details of
conductor constructions shall be given when known, or can be determined by inspection,
e.g:
– compacted;
– non-compacted;
– flexible (Class 5 and 6, according to IEC 60228);
– number and arrangement of strands;
– type of plating, if applicable;
– type of impregnation, water blocking, etc., if applicable;
– approximate indication of hardness, e.g. annealed, half-hard, hard;
– in the case of insulation-piercing connectors, material and thickness of insulation.
5.2 Connectors and tooling
The following information shall be recorded in the test report:
– the assembly technique that is to be used;
– tooling, dies and necessary setting;
– bolts, nuts, washers, torque, etc.;
– preparation of contact surfaces, if applicable;
– type, reference number and any other identification of the connector;
– in the case of insulation piercing connectors, type of insulation and installation temperature.
5.3 Range of approval
In general, tests made on one type of connector/conductor combination apply to that
arrangement only. However, to limit the number of tests the following is permitted:
– a connector which can be used on stranded round conductors or on stranded sector-
shaped conductors which have been rounded, is approved for both types if satisfactory
results are obtained on a compacted round conductor;
– a connector which covers a range of cross-sectional areas shall be approved, if satisfactory
results are obtained on the smallest and the largest cross-sectional area (see Note 2
below);
– if a connector is a through connector for two conductors of different cross-sectional areas,
shapes, or materials, and if the technique and the connector barrels used have already
been tested separately for each cross-sectional area, no additional test is necessary. If not,
and if it is required for bimetallic through connectors, additional tests shall be made using
the conductor having the highest temperature of the two conductors, as reference
conductor;
61238-1  IEC:2003 – 23 –
– if a manufacturer can clearly demonstrate that common and relevant connector design
criteria were used for a family of connectors, conformity to this standard is achieved by
successfully testing the largest, the smallest and two intermediate connector sizes;
Exception no.1: for a family of connectors consisting of five sizes, only the largest
connector, the smallest connector, and one connector of a representative intermediate size
need to be tested.
Exception no.2: for a family of connectors consisting of four sizes or less, only the largest
connector and the smallest connector need to be tested.
– in the case of range-taking connectors, the maximum and minimum conductor cross-
sectional area for the selected connectors shall be tested;
– satisfactory test results on insulation piercing connectors tested on PVC insulation at lower
temperatures for heat cycles and for short-circuits shall give approval of such connectors
for PVC insulation only;
– satisfactory test results of a connector on dry conductor shall give approval for its use on a
conductor of the same type from an impregnated paper insulated cable;
– for connectors where one or both sides are designed for a range of cross-sectional areas,
and a common clamping or crimping arrangement serves for the connection of the different
cross-sectional areas, then mechanical tests on conductors with the largest and smallest
cross-sectional areas shall be carried out according to Clause 7.
NOTE 1 Examples of relevant design criteria include
– compression reduction,
– number of contact screws or crimps,
– force per unit area of contact screw or crimp,
– ratio of amount of material of connector to that of conductor.
NOTE 2  Different types of water blocking may affect the performance.
6 Electrical tests
6.1 Installation
All conductors of the same cross-sectional area in the test loop shall be taken from the same
continuous core.
For each series of tests, six connectors shall be fitted in accordance with the manufacturer’s
instructions, on a bare conductor or on a conductor that has had the insulation removed before
assembly, to form a test loop together with the corresponding reference conductor.
For stranded conductors, potential between the strands at measuring points can cause errors
in measuring electrical resistance. Equalizers (see Annex A) shall be used to overcome this
problem and to ensure uniform current distribution in the reference conductor and between
connectors at the equalizer points.
In the case of insulation piercing connectors, the insulation shall be retained on the conductor
under the connector and for a distance of at least 100 mm outside the connector. Reference
conductor(s) with the insulation retained shall also be included in the test loop. If the connector
is to be tested according to Class B, there is no need for bare reference conductors.
The test loop shall be installed in a location where the air is calm. The ambient temperature of
the test location shall be between 15 °C and 30 °C.
For assembly of the IPC, the temperature shall be (23 ± 3) °C.

61238-1  IEC:2003 – 25 –
In the case of solid conductors, the potential measuring points shall be as close as possible to
the connector in order to reduce l and l close to zero.
a b
The test loop may be of any shape provided that it is arranged in such a way that there is no
adverse affect from the floor, walls and ceiling.
To permit the short-circuit tests (Class A connectors only) to be made easily, the loop can be
made dismantleable. In this case, the technology of the sectioning connections shall be such
that they do not influence the measurements, particularly from the point of view of temperature.
Retightening of bolts or screws of the connectors under test is not permitted.
6.1.1 Through connectors and terminal lugs
The test loop is shown in Figure 1, which indicates the dimensions that shall be used.
Where terminal lugs are to be tested, the palms shall be bolted to linking bars in accordance
with the manufacturer's instructions. These linking bars shall, at the point of connection, be of
the same dimensions and thickness as the palm, and also of the same material.
It may be necessary to adjust the thermal characteristics of the linking bar outside the point of
connection, to achieve the temperatures specified in 6.3. As an alternative to linking bars, tests
can be made on terminal lugs with palm connected direct to palm. In case of disagreement, the
method with linking bars shall be used.
If however it is requested that the terminal lug test includes an evaluation of the performance of
the bolted palm when connected to a plant terminal, then linking bar ends, or an intermediate
piece, shall be used of a material, size and surface coating agreed between the parties.
6.1.2 Branch connectors
When the branch connector is intended for a branch cross-sectional area equal to the main, or
a cross-sectional area immediately above or below the main, it is treated as a through
connector between the main and the branch, and the test method for through connectors is
applicable. In other cases, the test loop shall be as shown in Figure 2. Where a type of
connector makes it necessary for the main conductor to be cut, that part of the connector which
acts as a through connector, shall also be tested as for through connectors.
6.2 Measurements
6.2.1 Electrical resistance measurements
Measurements of electrical resistance shall be made at stages throughout the test as specified
in 6.3.
These measurements of resistance shall be made under steady temperature conditions of both
the test loop and test location. The ambient temperature shall be between 15 °C and 30 °C.

61238-1  IEC:2003 – 27 –
The recommended method is to pass a direct current of up to 10 % of the heat cycling current,
through the connectors and the reference conductor, without increasing the temperature and to
measure the potential difference between specific potential points. The ratio of potential
difference and direct current is the resistance between those points.
NOTE To improve the accuracy of the resistance measurement, it is recommended that the same direct current is
used throughout the test programme.
For branch conductors assembled in accordance with Figure 2, the whole of the measuring
current shall flow through that part of the connector whose potential difference is being
measured. Switches or disconnect points may be provided for this purpose.
Thermoelectric voltages may affect the accuracy of low resistance measurements (of the order
of 10 μΩ). If this is suspected, two resistance measurements shall be taken with the direct
measuring current reversed between readings. The mean of the two readings is then the actual
resistance of the sample.
The potential points shall be as indicated in Figure 3, and Annex B, and the various lengths
shown shall also be measured to enable the actual connector resistances to be determined.
The temperature of connector and reference conductor shall be recorded when resistance
measurements are made. For direct comparison, the resistance values shall be corrected to
20 °C. Information on the recommended method is also given in Annex B. Temperature
measurements at these locations shall be made during the heat cycling test.
Indirect resistance readings:
– voltage measurements shall have an accuracy within ±0,5 % or ±10 μV, whichever is the
greater;
– current measurements shall have an accuracy within ±0,5 % or ±0,1 A, whichever is
the greater.
Direct resistance readings:
Resistance measurements shall have an accuracy within ±1 % or ±0,5 μΩ, whichever is the
greater when the instrument is calibrated against a certified standard resistance.
6.2.2 Temperature measurements
The temperature measurements shall be made at stages throughout the test, as specified
in 6.3.
Temperatures of both connectors and reference conductors shall be measured at the points
indicated in Figure 3. The recommended method of temperature measurement is to use
thermocouples. Temperature readings shall have an accuracy within ±2 K.
6.3 Heat cycle test
The heat cycling test shall be made with alternating current.
6.3.1 First heat cycle
The object of the first heat cycle is to determine the reference conductor temperature to be
used for subsequent cycles and also to identify the median connector.
a) Non-IPC through connectors and terminal lugs
Current is circulated in the test loop, bringing the reference conductor to 120 °C at
equilibrium.
61238-1  IEC:2003 – 29 –
Equilibrium is defined as the moment when the reference conductor and the connectors do
not vary in temperature by more than ±2 K for 15 min.
If the temperature of the median connector (see 3.11) is equal to or greater than 100 °C,
the reference conductor temperature for subsequent heat cycles shall be deemed to be
120 °C. If not, then the current shall be increased until the median connector temperature
reaches 100 °C at equilibrium, subject to the reference conductor temperature not
exceeding 140 °C. If the temperature of the median connector does not reach 100 °C, even
with a reference conductor temperature of 140 °C, the test shall be continued at that
temperature. The measured reference conductor temperature θ shall then be used for
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subsequent heat cycles (120 °C ≤ θ ≤ 140 °C). The current I at equilibrium temperature
R N
shall be recorded in the test report.
NOTE 1 Where linking bars are used for terminal lugs, the temperature at the midpoint of the bar linking the palms
should also be measured. This temperature should be equal to the temperature of the reference conductor θ , with
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a tolerance of ±5 K.
b) Non-IPC branch connectors
Where it is necessary to use the circuit shown in Figure 2, current shall be circulated in the
test loop, bringing the main reference conductor and the three branch reference conductors
to 120 °C at equilibrium. To achieve this, the currents in the three branches shall be
adjusted by current injection or impedance control. If the median connector temperature
(see 3.11) is then equal to or greater than 100 °C, the reference conductor temperature for
subsequent heat cycles shall be deemed to be 120 °C. If not, then the current shall be
increased in the loop until the median connector temperature reaches 100 °C at
equilibrium, provided the reference conductors do not exceed 140 °C. It may be necessary
at this stage, and also at intervals throughout the test, to adjust the current in an individual
branch so as to ensure that each branch reference temperature is the same as the main
reference temperature. The measured reference conductor temperature θ on the main and
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branch conductors, shall then be used for subsequent heat cycles (120 °C ≤ θ ≤ 140 °C).
R
The current(s) I at equilibrium temperature in the main and branch conductors shall be
N
recorded in the test report.
c) IPC
For tests of IPCs, the same test loop as in Figure 1 or 2 shall be used except that
the insulated reference conductor(s) is (are) added in the circuit. During cycling, the
temperature on the median connector shall be modified to be 10 K higher than the
maximum conductor temperature in normal operation for which these type of connectors
are intended. However, the circulated current shall be limited so that the temperature of the
insulated reference conductor at equilibrium is not more than 10 K to 15 K above
the maximum conductor temperature in normal operation. In the case of branch connectors,
it may be necessary at intervals throughout the test, to adjust the current in an individual
branch so as to ensure that each branch reference temperature is the same as the main
reference temperature. The current(s) I at equilibrium temperature in the main and
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possible branch conductors shall be recorded in the test report.
NOTE 2 If a connector is used in an application where considerably higher temperatures are reached than the
maximum conductor temperature in normal operation, additional tests at higher temperature of the test loop may be
made, after agreement between manufacturer and user. The additional increase in temperature of the test loop
should be achieved by the application of thermal insulation.
6.3.2 Second heat cycle
The object of this second heat cycle is to determine the heat cycle duration and temperature
profile which will be used on the test loop for all subsequent heat cycles. Current is circulated
in the loop until the main reference conductor temperature reaches the value θ determined in
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+6
6.3.1, with a tolerance of K and the median connector temperature is stable within a band
of 2 K over a 10 min period.
61238-1  IEC:2003 – 31 –
An elevated current may be used to reduce the heating period. The duration of this elevated
current is given in Table 1. The current shall thereafter be decreased or regulated to a mean
value of the current close to I to ensure stable conditions during the median-connector control
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period. It may be necessary to use more than one cycle to determine the second heat cycle.
The reference conductor temperature shall be the control parameter, in order to keep the
temperature profile during the heat cycle test. In this way, the fluctuation of the ambient
temperature will not affect the temperature profile of the reference conductor.
Table 1 – Minimum elevated current heating time
Al 16 ≤ A ≤ 50 50 < A ≤ 150 150 < A ≤ 630 A > 630
Nominal conductor
mm
cross-sectional area, A
Cu A > 400
10 ≤ A ≤ 35 35 < A ≤ 95 95 < A ≤ 400
5 10 15 20
Time min
The reference temperature time (t ) heating profile, see Figure 4, determined in this way shall
be recorded and used for all subsequent cycles.
After the period t , follows a period t of cooling to bring the temperature of all con
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