EN 60974-1:2005

SLOVENSKI STANDARD
01-december-2005
1DGRPHãþD
SIST EN 60974-1:2000
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Arc welding equipment -- Part 1: Welding power sources
Lichtbogenschweißeinrichtungen -- Teil 1: Schweißstromquellen
Matériel de soudage à l'arc -- Partie 1: Sources de courant de soudage
Ta slovenski standard je istoveten z: EN 60974-1:2005
ICS:
25.160.30 Varilna oprema Welding equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD EN 60974-1
NORME EUROPÉENNE
EUROPÄISCHE NORM October 2005

ICS 25.160 Supersedes EN 60974-1:1998 + A1:2000 + A2:2003

English version
Arc welding equipment
Part 1: Welding power sources
(IEC 60974-1:2005)
Matériel de soudage à l'arc Lichtbogenschweißeinrichtungen
Partie 1: Sources de courant de soudage Teil 1: Schweißstromquellen
(CEI 60974-1:2005) (IEC 60974-1:2005)

This European Standard was approved by CENELEC on 2005-10-01. 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, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, 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

© 2005 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 60974-1:2005 E
Foreword
The text of document 26/307/FDIS, future edition 3 of IEC 60974-1, prepared by IEC TC 26, Electric
welding, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as
EN 60974-1 on 2005-10-01.
This European Standard supersedes EN 60974-1:1998 + A1:2000 + A2:2003.
The significant changes with respect to EN 60974-1:1998 are the following:
– the scope includes relationship to other parts of EN 60974;
– environmental conditions were changed (see 4.a and 4.e);
– conformity of components is given (see 5.3);
– the sequence of type test was changed (see 5.4);
– more precise requirements for measuring the no-load voltage during routine test are given
(see 5.5d);
– creepage values for printed circuit boards are implemented (see Table 2);
– requirements for enclosures are changed (see 6.2.1);
– requirements for primary leakage current are included (see 6.3.7 and Annex N);
– requirements for engine driven power sources are changed (see 7.1.2 and 7.3.2);
– requirements for supply circuit terminals are changed (see 10.4.3 and 10.4.4);
– requirements for cable anchorage are changed (see 10.5);
– requirements for coupling devices are changed (see 10.9);
– standard characteristic for plasma welding is included (11.2.6);
– requirements for welding cables are added (see 11.7);
– requirements for plastic material used as enclosure materials are added (see 14.2.1);
– requirements for manual handling are added (see 14.3.2);
– existing ISO symbols and labels are taken into account (see 15.3 and 17.2).
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) 2006-07-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2008-10-01
Annex ZA has been added by CENELEC.
__________
- 3 - EN 60974-1:2005
Endorsement notice
The text of the International Standard IEC 60974-1:2005 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60085 NOTE Harmonized as EN 60085:2004 (not modified).
IEC 60204-1 NOTE Harmonized as EN 60204-1:1997 (not modified).
IEC 62079 NOTE Harmonized as EN 62079:2001 (not modified).
IEC 62081 NOTE Harmonized as CLC/TS 62081:2002 (not modified).
__________
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE Where an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
1) 2)
IEC 60038 (mod) - Nominal voltages for low-voltage public HD 472 S1 1989
electricity supply systems + corr. February 2002

1)
IEC 60050-151 - International Electrotechnical - -
Vocabulary (IEV)
Part 151: Electrical and magnetic
devices
1)
IEC 60050-851 - Chapter 851: Electric welding - -

1) 2)
IEC 60112 - Method for the determination of the EN 60112 2003
proof and the comparative tracking
indices of solid insulating materials

1)
IEC 60245-6 - Rubber insulated cables - Rated - -
voltages up to and including 450/750 V
Part 6: Arc welding electrode cables

1) 2)
IEC 60309-1 - Plugs, socket-outlets and couplers for EN 60309-1 1999
industrial purposes + A11 2004
Part 1: General requirements
database
IEC 60417 Graphical symbols for use on - -
equipment
1) 2)
IEC 60445 - Basic and safety principles for man- EN 60445 2000
machine interface, marking and
identification - Identification of
equipment terminals and of terminations
of certain designated conductors,
including general rules for an
alphanumeric system
1) 2)
IEC 60529 - Degrees of protection provided by EN 60529 1991
enclosures (IP Code) + corr. May 1993

1)
Undated reference.
2)
Valid edition at date of issue.

- 5 - EN 60974-1:2005
Publication Year Title EN/HD Year
IEC 60664-1 1992 Insulation coordination for equipment
within low-voltage systems
Part 1: Principles, requirements and
tests
+ A1 2000
+ A2 2002 EN 60664-1 2003
1) 2)
IEC 60664-3 - Part 3: Use of coating, potting or EN 60664-3 2003
moulding for protection against pollution

1) 2)
IEC 60695-11-10 - Fire hazard testing EN 60695-11-10 1999
Part 11-10: Test flames - 50 W
horizontal and vertical flame test
methods
1) 2)
IEC 60974-7 - Arc welding equipment EN 60974-7 2005
Part 7:Torches
1) 2)
IEC 60974-12 - Part 12: Coupling devices for welding EN 60974-12 2005
cables
1) 2)
IEC 61140 - Protection against electric shock - EN 61140 2002
Common aspects for installation and
equipment
1) 2)
IEC 61558-2-4 - Safety of power transformers, power EN 61558-2-4 1997
supply units and similar
Part 2-4: Particular requirements for
isolating transformers for general use

1) 2)
IEC 61558-2-6 - Part 2-6: Particular requirements for EN 61558-2-6 1997
safety isolating transformers for general
use
1) 2)
CISPR 11 (mod) - Industrial, scientific and medical (ISM) EN 55011 1998
radio-frequency equipment - Radio
disturbance characteristics - Limits and
methods of measurement
NORME CEI
INTERNATIONALE
IEC
60974-1
INTERNATIONAL
Troisième édition
STANDARD
Third edition
2005-07
Matériel de soudage à l'arc –
Partie 1:
Sources de courant de soudage
Arc welding equipment –
Part 1:
Welding power sources
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МеждународнаяЭлектротехническаяКомиссия
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For price, see current catalogue

60974-1  IEC:2005 – 3 –
CONTENTS
FOREWORD.11

1 Scope.17
2 Normative references.17
3 Terms and definitions .19
4 Environmental conditions .33
5 Tests .35
5.1 Test conditions .35
5.2 Measuring instruments.35
5.3 Conformity of components .35
5.4 Type tests .37
5.5 Routine tests .37
6 Protection against electric shock.39
6.1 Insulation.39
6.2 Protection against electric shock in normal service (direct contact).47
6.3 Protection against electric shock in case of a fault condition (indirect contact) .51
7 Thermal requirements.59
7.1 Heating test .59
7.2 Temperature measurement.59
7.3 Limits of temperature rise .63
7.4 Loading test.67
7.5 Commutators and slip-rings .67
8 Abnormal operation.67
8.1 General requirements .67
8.2 Stalled fan test .69
8.3 Short circuit test .69
8.4 Overload test.71
9 Thermal protection.71
9.1 General requirements .71
9.2 Construction .71
9.3 Location .71
9.4 Operation .73
9.5 Resetting.73
9.6 Operating capacity.73
9.7 Indication.73
10 Connection to the input supply network .75
10.1 Supply voltage .75
10.2 Multi supply voltage .75
10.3 Means of connection to the supply circuit .75
10.4 Supply circuit terminals.77
10.5 Cable anchorage .81
10.6 Inlet openings .83
10.7 Supply circuit on/off switching device .83
10.8 Supply cables .85
10.9 Supply coupling device (attachment plug).85

60974-1  IEC:2005 – 5 –
11 Output .87
11.1 Rated no-load voltage.87
11.2 Type test values of the conventional load voltage.93
11.3 Mechanical switching devices used to adjust output .95
11.4 Welding circuit connections .95
11.5 Power supply to external devices .97
11.6 Auxiliary power output.97
11.7 Welding cables .99
12 Control circuits .99
13 Hazard reducing device .99
13.1 General requirements .99
13.2 Voltage reducing device. 101
13.3 Switching device for a.c. to d.c. 101
13.4 Disabling the hazard reducing device . 101
13.5 Interference with operation of a hazard reducing device . 101
13.6 Indication of satisfactory operation. 101
13.7 Fail to a safe condition. 103
14 Mechanical provisions. 103
14.1 General requirements . 103
14.2 Enclosure . 103
14.3 Handling means. 105
14.4 Drop withstand . 107
14.5 Tilting stability . 107
15 Rating plate . 107
15.1 General requirements . 107
15.2 Description . 109
15.3 Contents. 111
15.4 Tolerances . 117
15.5 Direction of rotation . 117
16 Adjustment of the output . 117
16.1 Type of adjustment . 117
16.2 Marking of the adjusting device. 117
16.3 Indication of current or voltage control . 119
17 Instructions and markings . 119
17.1 Instructions. 119
17.2 Markings . 123

Annex A (informative) Nominal voltages of supply networks. 125
Annex B (informative) Example of a combined dielectric test . 127
Annex C (normative) Unbalanced load in case of a.c. tungsten inert-gas welding power
sources. 129
Annex D (informative) Extrapolation of temperature to time of shutdown . 133
Annex E (normative) Construction of supply circuit terminals . 135
Annex F (informative) Cross-reference to non-SI units. 139
Annex G (informative) Suitability of supply network for the measurement of the true
r.m.s. value of the supply current. 141

60974-1  IEC:2005 – 7 –
Annex H (informative) Plotting of static characteristics. 143
Annex I (normative) Test methods for a 10 Nm impact. 145
Annex J (normative) Thickness of sheet metal for enclosures . 147
Annex K (informative) Examples of rating plates. 151
Annex L (informative) Graphical symbols for arc welding equipment . 159
Annex M (informative) Efficiency . 203
Annex N (normative) Primary leakage current measurement. 205

Bibliography . 209

Figure 1 – Measurement of leakage current of welding circuit .53
Figure 2 – Measuring network for primary leakage current .57
Figure 3 – Measurement of peak values .91
Figure 4 – Principle of the rating plate . 109
Figure B.1 – Combined high-voltage transformers . 127
Figure C.1 – Voltage and current during a.c. tungsten inert-gas welding. 129
Figure C.2 – Unbalanced voltage during a.c. tungsten inert-gas welding . 131
Figure C.3 – AC welding power source with unbalanced load . 131
Figure I.1 – Test set-up . 145
Figure K.1 – Single-phase transformer . 151
Figure K.2 – Three-phase rotating frequency converter. 153
Figure K.3 – Subdivided rating plate: single-/three-phase transformer rectifier . 155
Figure K.4 – Engine-generator-rectifier. 157
Figure L.1 – Input voltage power switch . 199
Figure L.2 – Arc force control potentiometer . 199
Figure L.3 – Remote receptacle and selector switches. 199
Figure L.4 – Terminals with inductance selector for MIG/MAG welding. 199
Figure L.5 – Process switch (MMA, TIG, MIG) . 201
Figure L.6 – Selector switch on AC/DC equipment . 201
Figure L.7 – Panel indicator lights (overheat, fault, arc striking, output voltage). 201
Figure L.8 – Setting pulsing parameters using digital display. 201
Figure N.1 – Diagram for leakage current meaurement at operating temperature for
single-phase connection of appliances other than those of class II. 205
Figure N.2 – Diagram for leakage current meaurement at operating temperature for
three-phase connection of appliances other than those of class II. 205
Figure N.3 – Diagram for leakage current measurement at operating temperature for
single-phase connection of class II appliances. 207
Figure N.4 – Diagram for leakage current measurement at operating temperature for
three-phase connection of class II appliances. 207

60974-1  IEC:2005 – 9 –
Table 1 – Minimum clearances for overvoltage category III .39
Table 2 – Minimum creepage distances.43
Table 3 – Insulation resistance .45
Table 4 – Dielectric test voltages.45
Table 5 – Minimum distance through insulation.53
Table 6 – Limits of temperature rise for windings, commutators and slip-rings .63
Table 7 – Limits of temperature rise for external surfaces.65
Table 8 – Cross-section of the output short-circuit conductor .69
Table 9 – Current and time requirements for protective circuits.79
Table 10 – Minimum cross-sectional area of the external protective copper conductor .79
Table 11 – Verification of continuity of the protective bonding circuit .81
Table 12 – Pull.83
Table 13 – Summary of allowable rated no-load voltages.91
Table 14 – Hazard reducing device requirements. 101
Table E.1 – Range of conductor dimensions to be accepted by the supply circuit
terminals. 135
Table E.2 – Spacing between supply circuit terminals . 137
Table F.1 – Cross-reference for mm to American wire gauge (AWG) . 139
Table F.2 – Cross reference for kW to horsepower (hp). 139
Table I.1 – Mass of the free fall weight and height of the free fall . 145
Table J.1 – Minimum thickness of sheet metal for steel enclosures. 147
Table J.2 – Minimum thickness of sheet metal for enclosures of aluminium, brass or
copper . 149
Table L.1 – Letters used as symbols . 161

60974-1  IEC:2005 – 11 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ARC WELDING EQUIPMENT –
Part 1: Welding power sources
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 provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
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.
International Standard IEC 60974-1 has been prepared by IEC technical committee 26: Electric
welding.
This third edition cancels and replaces the second edition published in 1998, amendment 1
(2000) and amendment 2 (2003) and constitutes a technical revision.
The significant changes with respect to the previous edition are the following:
– The scope includes relationship to other parts of IEC 60974.
– Environmental conditions were changed (see 4.a and 4.e).
– Conformity of components is given (see 5.3).
– Sequence of type test was changed (see 5.4).
– More precise requirements for measuring the no-load voltage during routine test are given
(see 5.5d).
60974-1  IEC:2005 – 13 –
– Creepage values for printed circuit boards are implemented (see Table 2).
– Requirements for enclosures are changed (see 6.2.1).
– Requirements for primary leakage current are included (see 6.3.7 and Annex N).
– Requirements for engine driven power sources are changed (see 7.1.2 and 7.3.2).
– Requirements for supply circuit terminals are changed (see 10.4.3 and 10.4.4).
– Requirements for cable anchorage are changed (see 10.5).
– Requirements for coupling devices are changed (see 10.9).
– Standard characteristic for plasma welding is included (11.2.6).
– Requirements for welding cables are added (see 11.7).
– Requirements for plastic material used as enclosure materials are added (see 14.2.1).
– Requirements for manual handling are added (see 14.3.2).
– Taken care of existing ISO symbols and labels (see 15.3 and 17.2).

The text of this standard is based on the following documents:
FDIS Report on voting
26/307/FDIS 26/311/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.
IEC 60974 consists of the following parts, under the general title Arc welding equipment:
Part 1: Welding power sources
Part 2: Liquid cooling systems
Part 3: Arc striking and stabilizing devices
Part 4: Safety, maintenance and inspection of arc welding equipment in use
Part 5: Wire feeders
Part 6: Limited duty manual metal arc welding power sources
Part 7: Torches
Part 8: Gas consoles for welding and plasma cutting systems
Part 10: Electromagnetic compatibility (EMC) requirements
Part 11: Electrode holders
Part 12: Coupling devices for welding cables
Part 13: Terms
___________
Under consideration.
60974-1  IEC:2005 – 15 –
The committee has decided that the contents of this publication will remain unchanged until the
maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
60974-1  IEC:2005 – 17 –
ARC WELDING EQUIPMENT –
Part 1: Welding power sources
1 Scope
This part of IEC 60974 is applicable to power sources for arc welding and allied processes
designed for industrial and professional use, and supplied by a voltage not exceeding that
specified in Table 1 of IEC 60038, or driven by mechanical means.
This part of IEC 60974 specifies safety and performance requirements of welding power
sources and plasma cutting systems.
This part of IEC 60974 is not applicable to welding power sources for manual metal arc welding
with limited duty operation which are designed mainly for use by laymen.
This part of IEC 60974 is not applicable to testing of power sources during periodic
maintenance or after repair.
NOTE 1 Typical allied processes are electric arc cutting and arc spraying.
NOTE 2 This part of IEC 60974 does not include electromagnetic compatibility (EMC) requirements.
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 60038, IEC standard voltages
IEC 60050(151), International Electrotechnical Vocabulary (IEV) – Part 151: Electrical and
magnetic devices
IEC 60050(851), International Electrotechnical Vocabulary (IEV) – Chapter 851: Electric
welding
IEC 60112, Method for the determination of the proof and the comparative tracking indices of
solid insulating materials
IEC 60245-6, Rubber insulated cables – Rated voltages up to and including 450/750 V – Part 6:
Arc welding electrode cables
IEC 60309-1, Plugs, socket-outlets and couplers for industrial purposes – Part 1: General
requirements
IEC 60417-DB:2002 , Graphical symbols for use on equipment
___________
“DB” refers to the IEC on-line database.

60974-1  IEC:2005 – 19 –
IEC 60445, Basic and safety principles for man-machine interface, marking and identification –
Identification of equipment terminals and of terminations of certain designated conductors,
including general rules for an alphanumeric system
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60664-1:1992, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
Amendment 1 (2000)
Amendment 2 (2002)
IEC 60664-3, Insulation coordination for equipment within low-voltage systems – Part 3: Use of
coating, potting or moulding for protection against pollution
IEC 60695-11-10, Fire hazard testing – Part 11-10: Test flames – 50 W horizontal and vertical
flame test methods
IEC 60974-7, Arc welding equipment – Part 7: Torches
IEC 60974-12, Arc welding equipment – Part 12: Coupling devices for welding cables
IEC 61140, Protection against electric shock – Common aspects for installation and equipment
IEC 61558-2-4, Safety of power transformers, power supply units and similar – Part 2-4:
Particular requirements for isolating transformers for general use
IEC 61558-2-6, Safety of power transformers, power supply units and similar – Part 2-6:
Particular requirements for safety isolating transformers for general use
CISPR 11, Industrial, scientific and medical (ISM) radio-frequency equipment – Electro-
magnetic disturbance characteristics – Limits and methods of measurement
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050(151),
IEC 60050(851) and IEC 60664-1, as well as the following, apply.
3.1
arc welding power source
equipment for supplying current and voltage and having the required characteristics suitable for arc
welding and allied processes
NOTE 1 An arc welding power source may also supply services to other equipment and auxiliaries for example
auxiliary power, cooling liquid, consumable arc welding electrode and gas to shield the arc and the welding area.
NOTE 2 In the following text, the term "welding power source" is used.
3.2
industrial and professional use
use intended only for experts or instructed persons
___________
A consolidated edition 1.2 (2002) exists that includes edition 1.0 and its amendments 1 (2000) and 2 (2002).

60974-1  IEC:2005 – 21 –
3.3
expert
competent person, skilled person
a person who can judge the work assigned and recognize possible hazards on the basis of
professional training, knowledge, experience and knowledge of the relevant equipment
NOTE Several years of practice in the relevant technical field may be taken into consideration in assessment of
professional training.
3.4
instructed person
person informed about the tasks assigned and about the possible hazards involved in
neglectful behaviour
NOTE If necessary, the person has undergone some training.
3.5
type test
test of one or more devices made to a given design to check if these devices comply with the
requirements of the standard concerned
3.6
routine test
test made on each individual device during or after manufacture to check if it complies with the
requirements of the standard concerned or the criteria specified
3.7
visual inspection
inspection by eye to verify that there are no apparent discrepancies with respect to provisions
of the standard concerned
3.8
drooping characteristic
external static characteristic of a welding power source which, in its normal welding range, is
such that the negative slope is greater than or equal to 7 V/100 A
3.9
flat characteristic
external static characteristic of a welding power source which, in its normal welding range, is
such that, as the current increases, the voltage either decreases by less than 7 V/100 A or
increases by less than 10 V/100 A
3.10
static characteristic
relationship between the voltage and the current at the output terminals of a welding power
source when connected to a conventional load
3.11
welding circuit
conductive material through which the welding current is intended to flow
NOTE 1 In arc welding, the arc is a part of the welding circuit.
NOTE 2 In certain arc welding processes, the welding arc may be established between two electrodes. In such a
case, the workpiece is not necessarily a part of the welding circuit.
3.12
control circuit
circuit for the operational control of a welding power source and/or for protection of the power
circuits
60974-1  IEC:2005 – 23 –
3.13
welding current
current delivered by a welding power source during welding
3.14
load voltage
voltage between the output terminals when the welding power source is delivering welding
current
3.15
no-load voltage
voltage, exclusive of any arc striking or arc stabilizing voltage, between the output terminals of
a welding power source when the external welding circuit is open
3.16
conventional value
standardized value that is used as a measure of a parameter for the purposes of comparison,
calibration, testing etc.
NOTE Conventional values do not necessarily apply during the actual welding process.
3.17
conventional welding condition
condition of the welding power source in the energized and thermally stabilized state defined by
a conventional welding current driven by the corresponding conventional load voltage through a
conventional load at rated supply voltage and frequency or speed of rotation
3.18
conventional load
practically non-inductive constant resistive load having a power factor not less than 0,99
3.19
conventional welding current
I
current delivered by a welding power source to a conventional load at the corresponding
conventional load voltage
NOTE The values of I are given as r.m.s. values for a.c. and arithmetic mean values for d.c.
3.20
conventional load voltage
U
load voltage of a welding power source having a specified linear relationship to the
conventional welding current
NOTE 1 The values for U are given as r.m.s. values for a.c. and arithmetic mean values for d.c.
NOTE 2 The specified linear relationship varies in accordance with the process (see 11.2).
3.21
rated value
assigned value, generally by the manufacturer, for a specified operating condition of a
component, device or equipment
3.22
rating
set of rated values and operating conditions

60974-1  IEC:2005 – 25 –
3.23
rated output
rated values of the output of a welding power source
3.24
rated maximum welding current
I
2max
maximum value of the conventional welding current that can be obtained at the conventional
welding condition from a welding power source at its maximum setting
3.25
rated minimum welding current
I
2min
minimum value of the conventional welding current that can be obtained at the conventional
welding condition from a welding power source at its minimum setting
3.26
rated no-load voltage
U
no-load voltage, measured in accordance with 11.1, at rated supply voltage and frequency or
rated no-load speed of rotation
NOTE If a welding power source is fitted with a hazard reducing device, this is the voltage measured before the
hazard reducing device has performed its function.
3.27
rated reduced no-load voltage
U
r
no-load voltage of a welding power source, fitted with a voltage reducing device, measured in
accordance with 11.1 immediately after the device acts to effect a reduction in the voltage
3.28
rated switched no-load voltage
U
s
d.c. no-load voltage of a welding power source, fitted with an a.c. to d.c. switching device
3.29
rated supply voltage
U
r.m.s. value of an input voltage for which the welding power source is designed
3.30
rated supply current
I
r.m.s. value of an input current to the welding power source at a rated conventional welding
condition
3.31
rated no-load supply current
I
input current to the welding power source at rated no-load voltage

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