EN ISO 17657-4:2007

SLOVENSKI STANDARD
01-september-2007
Uporovno varjenje - Merjenje jakosti varilnega toka pri uporovnem varjenju - 4. del:
Sistem umerjanja (ISO 17657-4:2005)
Resistance welding - Welding current measurement for resistance welding - Part 4:
Calibration system (ISO 17657-4:2005)
Widerstandsschweißen - Schweißstrommessung für das Widerstandsschweißen - Teil 4:
Kalibriersystem (ISO 17657-4:2005)
Soudage par résistance - Mesurage des courants en soudage par résistance - Partie 4:
Systeme d'étalonnage (ISO 17657-4:2005)
Ta slovenski standard je istoveten z: EN ISO 17657-4:2007
ICS:
25.160.10 Varilni postopki in varjenje Welding processes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 17657-4
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2007
ICS 25.160.10
English Version
Resistance welding - Welding current measurement for
resistance welding - Part 4: Calibration system (ISO 17657-
4:2005)
Soudage par résistance - Mesurage des courants en Widerstandsschweißen - Schweißstrommessung für das
soudage par résistance - Partie 4: Système d'étalonnage Widerstandsschweißen - Teil 4: Kalibriersystem (ISO
(ISO 17657-4:2005) 17657-4:2005)
This European Standard was approved by CEN on 19 May 2007.
CEN 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 CEN Management Centre or to any CEN 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 CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2007 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 17657-4:2007: E
worldwide for CEN national Members.

Foreword
The text of ISO 17657-4:2005 has been prepared by Technical Committee ISO/TC 44 "Welding and allied
processes” of the International Organization for Standardization (ISO) and has been taken over as EN ISO
17657-4:2007 by Technical Committee CEN/TC 121 "Welding", the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by December 2007, and conflicting national standards shall be withdrawn
at the latest by December 2007.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and United Kingdom.
Endorsement notice
The text of ISO 17657-4:2005 has been approved by CEN as a EN ISO 17657-4:2007 without any
modification.
INTERNATIONAL ISO
STANDARD 17657-4
First edition
2005-09-15
Resistance welding — Welding current
measurement for resistance welding —
Part 4:
Calibration system
Soudage par résistance — Mesurage des courants en soudage par
résistance —
Partie 4: Système d'étalonnage

Reference number
ISO 17657-4:2005(E)
©
ISO 2005
ISO 17657-4:2005(E)
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ii © ISO 2005 – All rights reserved

ISO 17657-4:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Construction of calibration system . 2
4.1 Reference welding current measuring system. 2
4.2 Test set-up. 2
4.3 Basic feature for calibration of welding current measuring system . 2
4.4 Basic feature for calibration of current sensor .4
4.5 Basic feature for calibration of welding current meter without sensor . 5
5 Physical environment and operating conditions . 6
6 Calibration requirements . 6
6.1 Reference welding current measuring system. 6
6.2 Reference current sensor . 6
6.3 Data acquisition device. 7
6.4 Test stage and power sources . 7
7 Test report . 7
7.1 Test report for calibration of welding current measuring systems. 7
7.2 Test report for calibration of current sensors . 8
7.3 Test report for calibration of welding current meters without sensors. 8
8 Test procedure . 9
8.1 General. 9
8.2 Calibration of welding current measuring system . 9
8.3 Calibration of current sensor . 10
8.4 Calibration of welding current meter without sensor . 10
8.5 Special calibration cases . 10
Annex A (informative) Measuring set-up . 12
Annex B (informative) Items to be recorded or filed as reference documentation for calibration . 17
Annex C (informative) Examples of the test report in accordance with this part of ISO 17657 . 19

ISO 17657-4:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 17657-4 was prepared by Technical Committee ISO/TC 44, Welding and allied processes, Subcommittee
SC 6, Resistance welding.
ISO 17657 consists of the following parts, under the general title Resistance welding — Welding current
measurement for resistance welding:
 Part 1: Guidelines for measurement
 Part 2: Welding current meter with current sensing coil
 Part 3: Current sensing coil
 Part 4: Calibration system
 Part 5: Verification of welding current measuring system

iv © ISO 2005 – All rights reserved

ISO 17657-4:2005(E)
Introduction
Requests for official interpretations of any aspect of this part of ISO 17657 should be directed to the
Secretariat of ISO/TC 44/SC 6 via your national standards body. A complete listing of these bodies can be
found at http://www.iso.org.
INTERNATIONAL STANDARD ISO 17657-4:2005(E)

Resistance welding — Welding current measurement for
resistance welding —
Part 4:
Calibration system
1 Scope
This part of ISO 17657 specifies calibration systems and calibration procedures for welding current measuring
systems, current sensors, welding current meters and monitoring devices with current sensor used for
measuring welding current in resistance welding with alternating current of 50 Hz or 60 Hz, or with direct
current.
The procedures are applicable for a current range between 0,5 kA and 25 kA.
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.
ISO 669, Resistance welding — Resistance welding equipment — Mechanical and electrical requirements
ISO 17657-2, Resistance welding — Welding current measurement for resistance welding — Part 2: Welding
current meter with current sensing coil
ISO 17657-3:2005, Resistance welding — Welding current measurement for resistance welding — Part 3:
Current sensing coil
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 669 and the following apply.
3.1
test (current) sensor
current sensor to be calibrated
3.2
reference (current) sensor
current sensor calibrated in highly accurate condition, used for calibration of current sensors
3.3
test welding current meter
welding current meter to be calibrated
ISO 17657-4:2005(E)
3.4
non-inductive shunt
high precision and low value resistance with a very low inductive component
3.5
analog-to-digital converter
ADC
device to convert analog input signals into digital signals
3.6
data acquisition device
instrument or device used to acquire analog data, which tracks changes in physical variables such as voltage,
current and temperature
3.7
measuring accuracy of reference welding current measuring system
sum of measuring accuracy values of each component calibrated by a certified reference equipment (e.g.
reference sensor, integrator, ADC etc.)
4 Construction of calibration system
4.1 Reference welding current measuring system
Components of a reference welding current measuring system shall be calibrated by certified reference
equipment in accordance with Clause 6. The reference welding current measuring system consists of a
calibrated current sensor, a data acquisition system and a display unit or a recorder.
4.2 Test set-up
The test set-up consists of a test stage or an appropriate circuit for conducting high current, and a power
source with a current control unit for supplying a test current.
All signal cables shall be twisted and shielded. The cable resistance shall be very small and negligible
compared to the impedance of the current sensor. Typical examples of the test set-up are shown in Annex A.
NOTE A resistance welding machine/transformer can be used as a test set-up.
4.3 Basic feature for calibration of welding current measuring system
A welding current meter with a current sensor should be calibrated in a set consisting of the meter and the
sensor. Calibration systems for a welding current meter with its sensor consist of a test set-up, a reference
welding current measuring system and the welding current measuring system to be tested. The function of a
reference welding current meter can be replaced with a calibrated data acquisition device. Figure 1 shows the
basic features required for calibration of welding current measuring system.
2 © ISO 2005 – All rights reserved

ISO 17657-4:2005(E)
a)
b)
Key
1 reference welding current measuring system 6 test welding current meter
2 reference sensor 7 reference welding current meter
3 test sensor 8 test set-up
4 alternating current or direct current power source 9 data acquisition device
5 secondary circuit
Figure 1 — Basic feature for calibration of welding current measuring system
ISO 17657-4:2005(E)
4.4 Basic feature for calibration of current sensor
A calibration system for a current sensor consists of a test set-up, a reference welding current measuring
system and a calibrated data acquisition device connected to the current sensor to be tested. The function of
the reference welding current meter can be replaced by using another channel of the data acquisition device.
Figure 2 shows the basic feature required for the calibration of current sensor.

a)
b)
Key
1 reference welding current measuring system 5 secondary circuit
2 reference sensor 6 data acquisition device
3 test sensor 7 reference welding current meter
4 alternating current power source 8 data acquisition device
Figure 2 — Basic feature for the calibration of current sensor
4 © ISO 2005 – All rights reserved

ISO 17657-4:2005(E)
4.5 Basic feature for calibration of welding current meter without sensor
A calibration system for a welding current meter of the high-impedance integrator type without current sensor
consists of a calibrated data acquisition device of the high-input-impedance integrator type, a calibrated
reference sensor, and the test welding current meter. See Figure 3 a). The welding current meter to be tested
is connected to the same output port of the reference current sensor. The data acquisition device shall not be
replaced by a reference welding current meter of the low-impedance integrator type.
For calibration of a welding current meter with the low impedance integrator unit, and when two reference coils
are used for the calibration, the calibration system shall consist of a calibrated reference welding current
measuring system and a calibrated second reference sensor connected to the welding current meter to be
tested. See Figure 3 b).
a)
b)
Key
1 reference welding current measuring system 5 secondary circuit
2 reference sensor 6 test welding current meter
3 second reference sensor 7 reference welding current meter
4 alternating current or direct current power source 8 data acquisition device
Figure 3 — Basic feature for calibration of welding current meter without sensor
ISO 17657-4:2005(E)
5 Physical environment and operating conditions
Unless otherwise specified, the calibration system shall be capable of operating under the following conditions
without any adverse effect on its accuracy. Any deviation from these conditions shall be agreed upon between
the test laboratory and the client.
 at an ambient air temperature between +5 °C and +40 °C;
 in relative humidity up to 95 %;
 at altitudes up to 1 000 m above mean sea level.
6 Calibration requirements
6.1 Reference welding current measuring system
Components of the reference welding current measuring system shall be calibrated by using certified
reference equipment at least once a year. The total measuring accuracy is defined as the sum of measuring
accuracy of each component of the reference welding current measuring system and shall be better than that
stipulated for the highly accurate class stipulated in ISO 17657-2.
The specification, name of certifying test body and relevant data for the reference welding current measuring
system, including the data acquisition device, and the reference current sensor shall be recorded on all
documentation. See Annex B.
6.2 Reference current sensor
Properties of reference current sensor shall be measured accurately with no external influences (e.g. strong
magnetic field caused by the high current) and calibrated by using certified reference equipment at a full wave
alternating current of 50 Hz or 60 Hz, or direct current.
In the case of using a non-inductive shunt as the reference current sensor, the conversion coefficient shall be
between 10 mV/kA and 150 mV/kA, and the error shall be less than ± 0,25 %. The phase shift between a
measured welding current and the output voltage shall be less than 1° for a sinusoidal wave current of 10 kHz.
Measuring accuracy of the reference current sensor including positioning error shall be within ± 0,5 %, or the
position should be fixed with pre-mounted current sensors on the current conductor to prevent any positioning
error.
NOTE A current sensing coil used as a reference current sensor should be made with as low internal impedance as
possible. Recommended specifications for a current sensing coil to be cased as a reference current sensor are shown
below:
 toroidal coil with return winding known as a Rogowski-type coil;
 L < 250 µH;
 r < 50 Ω;
i
 K: measuring accuracy shall be within ± 0,25 %;
 R = 1 000 Ω (± 0,2 % and non-inductive type).
L
6 © ISO 2005 – All rights reserved

ISO 17657-4:2005(E)
6.3 Data acquisition device
The data acquisition device shall be designed with an ADC (analog to digital converter) of the 12-bit type or
higher, and with at least two channels as the input port. Each channel datum shall be simultaneously captured,
and sampled. The sampling rate per channel shall be equal to or faster than 10 000 samples, and the input
impedance shall be higher than 500 kΩ.
Calibration of the data acquisition device shall be carried out by using certified reference equipment. The
measuring accuracy for each gain of each channel shall be reported as a document.
6.4 Test stage and power sources
The test set-up shall be capable of delivering the necessary current value for the calibration. This depends on
the final application and the limits of the test set-up. The test set-up shall be capable of delivering at least four
current values within range of the final application between the minimum and maximum current values of the
described range of calibration.
A multi-turn secondary circuit is applicable to reduce the power source capacity. Examples of test set-up are
given in Annex A.
An alternating current resistance welding machine can be used as the power source on condition that the
current value can be controlled by changing the primary tap of the transformer, etc., and the current shall be
delivered in different r.m.s. (root mean square) levels. A direct-current resistance welding machine can be also
used as the power source.
7 Test report
7.1 Test report for calibration of welding current measuring systems
The following shall be recorded during calibration of a welding current measuring system including monitoring
devices with its coil for measuring welding current:
a) type and name of the reference wel
...