SIST EN 50504:2009

SLOVENSKI STANDARD
SIST EN 50504:2009
01-januar-2009
1DGRPHãþD
SIST ENV 50184:2002
9DOLGDFLMDRSUHPH]DREORþQRYDUMHQMH
Validation of arc welding equipment
Validierung von Lichtbogenschweißeinrichtungen
Validation du matériel de soudage à l'arc
Ta slovenski standard je istoveten z: EN 50504:2008
ICS:
25.160.30 Varilna oprema Welding equipment
SIST EN 50504:2009 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

SIST EN 50504:2009

---------------------- Page: 2 ----------------------

SIST EN 50504:2009

EUROPEAN STANDARD
EN 50504

NORME EUROPÉENNE
July 2008
EUROPÄISCHE NORM

ICS 25.160.10


English version


Validation of arc welding equipment



Validation du matériel de soudage à l'arc Validierung von
Lichtbogenschweißeinrichtungen





This European Standard was approved by CENELEC on 2008-06-01. 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, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the 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


© 2008 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50504:2008 E

---------------------- Page: 3 ----------------------

SIST EN 50504:2009
EN 50504:2008 – 2 –
Foreword
This European Standard has been prepared by the Technical Committee CENELEC TC 26A,
Electric arc welding equipment.
The text of the draft was submitted to the formal vote and was approved by CENELEC as
EN 50504 on 2008-06-01.
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) 2009-06-01

– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2011-06-01

This European Standard has been developed under the authority of CLC/TC 26A, Electric arc
welding equipment. Welding is considered to be a special process because the final result
may not always be capable of being verified by testing, hence it requires continuous control
and/or adherence to documented procedures.
This European Standard has been developed to identify the controls and procedures required.
It requires the use of calibrated welding equipment, then the quality/consistency of the weld
depends upon accurate and repeatable setting of parameters such as current, voltage, speed,
gas flow, etc.
This European Standard concentrates on validating equipment built to the constructional
standard EN 60974-1. The accuracy of this equipment is designated as standard grade.
A higher level of accuracy (precision grade) is introduced in this document.
As a code of practice, this European Standard takes the form of guidance and
recommendations. It should not be quoted as if it were a specification and particular care
should be taken to ensure that claims of compliance are not misleading.
A standard does not purport to include all necessary provisions of a contract. Users of
standards are responsible for their correct application.
Compliance with a standard does not of itself confer immunity from legal obligations.
__________

---------------------- Page: 4 ----------------------

SIST EN 50504:2009
– 3 – EN 50504:2008
Contents
Introduction . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Validation accuracies . 7
5 Consistency . 8
6 Frequency of validation and calibration . 8
7 Validators of welding equipment . 8
8 Validation . 8
8.1 General . 8
8.2 Manual metal arc welding with covered electrodes . 9
8.3 Tungsten inert gas . 9
8.4 Metal inert/active gas and flux cored arc welding . 10
8.5 Auxiliary co mponents . 10
9 Validation techniques . 10
9.1 General . 10
9.2 Safety precautions . 10
9.3 Instrumentation. 11
9.4 Power source loads . 12
9.5 Method . 13
10 Validation labels and ce rtifi c ates . 14
10.1 Validation labels . 14
10.2 Validation certificate . 15
Annex A (informative) Accuracies for precision grade power sources . 16
Annex B (informative) Wire feed equipment . 17
B.1 Validation accuraci es . 17
B.2 Requirements for validation . 17
B.3 Method . 18
Annex C (informative) Slope, pulse and synergic controls . 19
C.1 Validation accuracy . 19
C.2 Requirements for validation . 19
C.3 Method . 19
C.4 Pulsed MIG and synergic controls . 20
Annex D (informative) Precautions to be taken with TIG welding equipment . 21
Annex E (informative) Validation of ancillary components in a welding s ystem . 22
Annex F (informative) Voltage drops in the welding circuit . 23
Bibliography . 25
Figure
Figure F.1 . 23
Tables
Table 1 – Validation accuracies for standard grade power sources . 7
Table A.1 – Validation accuracies for precision grade power sources . 16
Table B.1 – Validation accuracies for wire feed equipment . 17
Table F.1 – Voltage drop in copper and aluminium welding cables at normal and elevated
temperatures . 24

---------------------- Page: 5 ----------------------

SIST EN 50504:2009
EN 50504:2008 – 4 –
Introduction
The quality and consistency of a weld depends on the welder, the materials and the welding
equipment. Variability in the output of the welding equipment will affect the quality of the weld.
In some arc welding processes, e.g. MMA, the welder controls the process through his
experience and measurement of run out length is used to monitor the heat input. However, in
other arc welding processes the quality of the weld depends upon accurate and repeatable
setting of parameters such as current, voltage, speed, gas flow, pulse characteristics, etc.
The relevant construction standard for arc welding equipment is EN 60974-1. This standard
sets the reference level for the accuracy and consistency of the welding output. EN 60974-1
derives its specification for performance accuracy from the requirements of manual welding.
In manual welding the welder plays a key role in adapting and adjusting the output of the
equipment to meet the requirements of the weld. This adaptability allows equipment to be
constructed with a relaxed specification for calibration of output.
Mechanised welding methods lack the skilled adaptability of the manual welder and require
precise control of all aspects of the welding process. The control of the output of the welding
equipment is of particular importance. Manufacturers have responded to this need by
producing equipment with an accuracy of output control and calibration, which exceed the
requirements of EN 60974-1.
In addition to the demands of mechanized welding, manual welding methods have become
more refined and welding procedures often call for the precise control of power source
outputs to limit the freedom of the manual welder in order to produce particular results.
The improvement in equipment construction, the adoption of mechanized welding, the
introduction of quality assurance programmes and the increased understanding of the factors
which control weld quality have led to the demand for more rigorous calibration and validation
of welding equipment performance.
The term calibration has been used in the foregoing text to introduce the general subject of
checking that the welding equipment output meets the manufacturer's specification and is fit
for the purpose of making welds. This is a commonly accepted term for this checking
operation but it does not meet the strict definition of the word calibration.
Clause 3 of this document gives the definition of calibration. The operation of calibration can
be applied only to determining and adjusting the errors of a measuring instrument. An item of
welding equipment is not a measuring instrument though the meters fitted to the welding
equipment are and can be calibrated. The difficulty of terminology and the checking task is
further compounded as many pieces of welding equipment do not have calibrated outputs but
are scaled in arbitrary units. Again this is a function of the manual welding usage in which the
skill of the manual welder is used to adjust and set the welding variables. It is necessary to
use an alternative term to describe the operation of verifying that the welding equipment is fit
for the intended purpose. The term selected is validation.
Validation is the operation which verifies that the welding equipment conforms to the
operating specification for that equipment. If the equipment fails to conform to the
specification then the correction of the errors within the equipment is outside the scope of this
European Standard. That operation is the province of the manufacturers or equipment
specialists.

---------------------- Page: 6 ----------------------

SIST EN 50504:2009
– 5 – EN 50504:2008
It is implicit in the introduction of a more rigorous standard of accuracy of control of output for
welding equipment that the scope of application of that standard should be defined. This
European Standard defines two levels of accuracy. One is derived directly from EN 60974-1
and is called standard grade. A higher level of accuracy for more exacting welding
applications is defined, called precision grade, and this is given in Annex A for information.
The use of precision grade is dependent upon the welding application.
The welding equipment covered by this European Standard will be fitted with controls
intended to regulate the output of the welding equipment. The controls may be scaled in
absolute units (amperes, volts and metres per minute) or in arbitrary units (numbers, letters,
geometrical marks). Controls scaled in absolute units may be validated and the consistency of
those controls scaled in arbitrary units may be assessed.
The welding equipment may be fitted with meters that measure the output of the equipment
and these meters should normally be validated against the appropriate standard, unless a
different method is used to control the welding process.
The use of meters and measuring instrument packages with welding equipment that is
required to produce welds of integrity and reliability is strongly recommended.
This code of practice recommends the use of resistive loads to validate the power source and
associated meters. Alternatively, independent instrumentation may be used to monitor the
welding process, rather than validating the power source itself. The method of control and
type of instrumentation should be detailed on the welding procedure sheet.

---------------------- Page: 7 ----------------------

SIST EN 50504:2009
EN 50504:2008 – 6 –
1 Scope
This European Standard specifies validation methods for arc welding equipment constructed
and used to the accuracy specified in EN 60974-1 or other equivalent standards. The
accuracy of this equipment is designated as standard grade.
This European Standard is applicable to
a) arc welding power sources,
b) wire feeders,
c) welding instrumentation.
This European Standard is not applicable to arc striking and stabilizing device.
Calibration, verification and validation of equipment for other welding processes and ancillary
equipment which may affect the quality of the weld, e.g. flow gauges, thermocouples, robots
and manipulators are given in EN ISO 17662.
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.
EN 60051-1:1998, Direct acting indicating analogue electrical measuring instruments and
their accessories – Part 1: Definitions and general requirements common to all parts
(IEC 60051-1:1997)
EN 60974-1, Arc welding equipment – Part 1: Welding power sources (IEC 60974-1)
EN ISO 17662, Welding – Calibration, verification and validation of equipment used for
welding, including ancillary activities (ISO 17662)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 60974-1 and the
following apply.
3.1
calibration
operations for the purpose of determining the magnitude of the errors of a measuring
instrument and if necessary to determine other metrological properties
3.2
validation
operations for the purpose of demonstrating that an item of welding equipment or a welding
system conforms to the operating specification for that welding equipment or system
3.3
accuracy
closeness of an observed quantity to the defined or true value

---------------------- Page: 8 ----------------------

SIST EN 50504:2009
– 7 – EN 50504:2008
3.4
consistency test
test to determine the repeatability of the equipment output over a period of time
NOTE The results obtained from the present validation are compared to the results of the initial tests. The
repeatability/consistency is the difference between these readings.
3.5
class
designation according to the accuracy of a measuring instrument conforming to EN 60051-1
NOTE For example class 2,5 refers to ± 2,5 % full scale deflection.
3.6
portable welding monitor (brief case monitor)
assembly of measuring instruments packaged in a portable case used to measure, record
and/or analyse the welding equipment output
3.7
standard grade
grade of validating equipment built to the constructional standard EN 60974-1
3.8
precision grade
grade of validating equipment built to the constructional standard EN 60974-1 but with a
higher level of accuracy for more exacting welding applications
NOTE See Annex A for power sources and Annex B for wire feeders.
4 Validation accuracies
When tested in accordance with Clause 9, the validation accuracies for standard grade power
source controls and instrumentation should conform to Table 1.
Table 1 – Validation accuracies for standard grade power sources
Quantity Accuracy
Current and voltage ± 10 % of the true value, between 100 % and
25 % of the maximum setting
± 2,5 % of the maximum setting, below 25 % of
the maximum setting
Analogue meters Class 2,5 See 3.5
Digital meters
- Current ± 2,5 % of maximum rated welding current
- Voltage ± 2,5 % of no-load voltage, or
according to the manufacturer′s
specification

Validation may be carried out over a limited range, as agreed by the manufacturer and user or
specified in the welding procedure.

---------------------- Page: 9 ----------------------

SIST EN 50504:2009
EN 50504:2008 – 8 –
5 Consistency
It is recognized that the consistency of the equipment is important and in Clause 9 tests for
consistency are recommended.
A consistency test should be carried out on controls, which are not graduated in absolute
units.
Absolute values are assigned to control positions during an initial characterization. The
results obtained from subsequent tests are compared to initial values to determine the
consistency of the output.
The same percentage values for accuracy, as specified in Table 1, should be used in the
consistency test as for standard or precision grade as appropriate.
6 Frequency of validation and calibration
The welding equipment should be validated or calibrated at yearly intervals. Following an
initial consistency test it is recommended that the equipment be retested after three months.
It may be necessary to validate or calibrate at more frequent intervals, depending upon the
recommendation of the manufacturer, the requirements of the user, or where there is reason
to believe that the performance of the equipment may have deteriorated. Validation should
always be carried out after any repair or operation liable to affect the validation.
NOTE Recommendations for precision grade equipment are given in Annex A.
7 Validators of welding equipment
The welding equipment should be validated in accordance with Clause 9 by an expert, using
equipment which has calibration traceable to national standards.
Validation does not require third party certification although an equipment repairer or
validation agent often carries it out. Manufacturers of equipment may provide a validation
service or the users may carry out the work themselves.
8 Validation
8.1 General
Unless specified otherwise, e.g. by the user, all power source meters and controls, which are
graduated in absolute units and adjust the output, shall be validated.
The requirements and method of power source and meter validation will depend on the type of
power source, i.e. whether it is a constant current (drooping characteristic) or constant
voltage (flat characteristic) power source.
Welding power sources can be classified as follows:
a) a.c. power sources with constant current (drooping characteristic);
b) d.c. power sources with constant current (drooping characteristic);
c) d.c. power sources with constant voltage (flat characteristic).
CAUTION  The output of a constant voltage power source should not be short-circuited as a
very high current will flow; use a load resistor.

---------------------- Page: 10 ----------------------

SIST EN 50504:2009
– 9 – EN 50504:2008
Welding power sources may have analogue or digital meters fitted. The general practice is to
fit arithmetic mean instruments on direct current power sources and r.m.s. instruments on
alternating current power sources.
Arithmetic mean analogue instruments measure the average or mean value of the
instantaneous parameter with respect to time. r.m.s. analogue instruments give an indicated
rather than a true r.m.s. reading, see 9.3.
Digital meters may give true or indicated r.m.s. readings. For some equipment a single digital
meter may be used to measure a.c. and d.c. voltage and current. Expert knowledge may be
required to validate such equipment and the manufacturer should be consulted.
The standard methods of measurement are as follows:
a) d.c. welding supplies shall be measured with averaging techniques;
b) a.c. supplies shall be measured with root mean square methods using true r.m.s. meters
or using indicated r.m.s. meters (i.e. assuming pure sinusoidal form).
NOTE For power sources with non-sinusoidal waveforms e.g. square waves, averaging techniques may be used
and the manufacturer should be consulted (see 9.3).
8.2 Manual metal arc welding with covered electrodes
Manual metal arc (MMA) power sources have a constant current characteristic with a.c. or d.c.
output. The current control if marked in absolute units should be validated at conventional
load voltages. An arbitrarily marked scale should be checked for consistency.
The MMA process is often controlled by measurement of run-out length where measurement
of welding current is not necessary. However, if accurate measurement of the welding current
is required it is preferable to use a calibrated ammeter (fitted to the power source or
separate), or to use independent monitoring equipment.
MMA power sources do not have voltage controls but could be fitted with voltmeters, which
can be calibrated.
8.3 Tungsten inert gas
Tungsten inert gas (TIG) power sources have a constant current characteristic with a.c. or
d.c. output. The current control should be marked in absolute units and can be validated at
conventional load voltages. Generally, TIG power sources are fitted with ammeters and
possibly voltmeters, which can be calibrated. TIG power sources do not have voltage controls
TIG welding power sources are used in complex TIG welding systems and it may be required
to validate the system with load conditions, which closely duplicate the arc load conditions.
The resistance of the load is calculated for a specific welding condition using the welding
current and the arc voltage at that current. The welding conditions could be taken from the
welding procedure. Alternatively, a stable arc may be used with a mechanically held torch with
or without arc voltage control.
CAUTION  Care should be taken to ensure damage does not occur to instrumentation. See
Annex D for recommended precautions.
A validation method for pulsed TIG power sources is recommended in Annex C.

---------------------- Page: 11 ----------------------

SIST EN 50504:2009
EN 50504:2008 – 10 –
8.4 Metal inert/active gas and flux cored arc welding
Metal inert/active gas (MIG/MAG) and flux cored arc welding (FCW) power sources usually
have a constant voltage characteristic with a d.c. output.
The voltage control may be scaled in absolute or arbitrary units. The voltage control sets the
no-load voltage, and the voltage will fall slightly as current is drawn (typically 3 V to 5 V per
100 A). Some power sources have a slope control that may be used to adjust the static
characteristic and the setting of this control should be noted on the validation certificate.
The voltage control if marked in absolute units should be validated at no-load voltages.
An arbitrarily marked scale should be checked for reproducibility / consistency.
MIG/MAG and FCW power sources do not usually have current controls. The output current of
such a welding power source is generally controlled by the wire feed speed setting which is
set on the wire feeder control panel. The current varies automatically to regulate the burn off
rate of the consumable electrode. See Annex B on wire feed rate consistency and validate the
wire feeder if necessary.
If accurate measurement of the welding current and voltage is required it is preferable to use
an ammeter and voltmeter (fitted to the power source or separate) which can be calibrated or
to use independent monitoring equipment.
CAUTION  Do not short-circuit the output of a constant voltage power source as a very high
current will flow; use a load resistor.
For synergically controlled and pulsed MIG power sources, a validation method is
recommended in Annex C.
8.5 Auxiliary components
For validation of auxiliary components see Annex E.
9 Validation techniques
9.1 General
It is recognized that manufacturers have developed many specialized methods of validating
their welding equipment that may require detailed knowledge of the construction or access to
the interior of the equipment. The validation methods described in this European Standard are
intended to enable the user to check that the equipment is fit for the intended purpose without
the manufacturer's specialist knowledge. However, some of the methods of measurement
described may require specialist knowledge or apparatus.
9.2 Safety precautions
The validator should observe all normal welding safety precautions. Welding equipment
should be installed and used in accordance with CLC/TS 62081. If a TIG power source is
being validated using a welding arc as a power source load, protective clothing and eye
protection should be worn.
The validator should pay particular attention to safety earthing recommendations. Special
attention should be given to the connection of measuring instruments and the welding current
circuit to prevent high current passing through the instruments.

---------------------- Page: 12 ----------------------

SIST EN 50504:2009
– 11 – EN 50504:2008
9.3 Instrumentation
The general rule for the selection of measuring instruments for use in validation tasks is that
they should conform to the following:
a) they should be in good condition;
b) they should be calibrated by a recognized calibrator with standards traceable to a national
standard;
c) they should be at least twice and preferably five times more accurate, than the accuracy
required for the validation grade.
The type of measurement and meter will be specified for the grade of accuracy and the type
of electrical output of the power source.
It is proposed that only three measuring terms be used for describing the basic electrical
measuring techniques:
a) instantaneous value;
b) mean value;
c) r.m.s. value.
NOTE The r.m.s. value may be `true' or `indicated'. Some meters measure r.m.s. directly (`true' r.m.s.) but many
measure the mean and indicate 1,11 times the mean to give an equivalent to the r.m.s. value for a true sine wave.
The straightforward measurement of welding parameters is complicated by the following
factors:
a) the current waveform is usually complex, i.e. the direct current has some fluctuating
component and the alternating current is not sinusoidal;
b) the measurement of current from the output of power sources with a large ripple content,
especially some types of inverter direct current power sources, will produce different
results depending upon the type of meter being used;
c) the shape of the waveform will
...