IEC 60974-6:2010
(Main)Arc welding equipment - Part 6: Limited duty equipment
Arc welding equipment - Part 6: Limited duty equipment
IEC 60974-6:2010 specifies safety and performance requirements applicable to limited duty arc welding and cutting power sources, and auxiliaries designed for use by laymen. Electrically powered equipment is intended to be connected to the single phase public low-voltage supply system. Engine driven power sources can not exceed output power of 7,5 kVA. This second edition cancels and replaces the first edition published in 2003. It constitutes a technical revision. The main significant technical changes with respect to the previous edition are the following:
- extension of the scope;
- amendment of the title;
- touch current at fault condition (see 6.3.7);
- new definition of thermal requirements based two independent devices, one for thermal protection and one for thermal control (see 7.1);
- new definition for thermal performances at 20 °C (see 7.2);
- thermal safety requirements are based on operating temperature for normal condition and maximum temperature in overload condition (see 7.4);
- addition of abnormal operation test for thermal control device (see 10.4);
- new requirement for auxiliaries (see Clause 16);
- new rating plate definition (see Clause 17);
- introduction of new mandatory warning symbols (see 12.1.117.3, Box 17b) and 19.2);
- induced changes due to publication of IEC 60974-1:2005.
This publication is to be read in conjunction with IEC 60974-1:2005.
Matériel de soudage à l'arc - Partie 6: Matériel à service limité
La CEI 60974-6:2010 spécifie les exigences de sécurité et de performance qui s'appliquent aux sources de courant de soudage et de coupage à l'arc à service limité et dispositifs externes conçus pour être utilisées par des non professionnels. Le matériel électrique est prévu pour être connecté à un système d'alimentation public à basse tension et monophasé. Les sources de courant de soudage à moteur thermique ne peuvent pas dépasser une puissance de sortie de 7,5 kVA. Cette deuxième édition annule et remplace la première édition parue en 2003. Elle constitue une révision technique. Les modifications techniques majeures par rapport à l'édition précédente sont les suivantes:
- élargissement du domaine d'application;
- changement du titre;
- courant de contact en cas de défaut (voir 6.3.7);
- nouvelle définition des exigences thermiques basée sur deux dispositifs indépendants, l'un pour la protection thermique et l'autre pour la commande thermique (voir 7.1);
- nouvelle définition pour performances thermiques à 20 °C (voir 7.2);
- les exigences pour la sécurité thermique sont basées sur la température de fonctionnement à l'état normal et la température maximale à l'état de surcharge (voir 7.4);
- ajout de l'essai de fonctionnement anormal des dispositifs de commande thermique (voir 10.4);
- nouvelle exigence pour les dispositifs auxiliaires (voir Article 16);
- nouvelle plaque signalétique (voir Article 17);
- introduction de nouveaux symboles d'avertissement obligatoires (voir 12.1.1, 17.3, case 17b) et 19.2);
- modifications induites en fonction de la pubilcation de la CEI 60974-1:2005.
Cette publication doit être lue conjointement avec la CEI 60974-1:2005.
General Information
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Standards Content (Sample)
IEC 60974-6 ®
Edition 2.0 2010-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Arc welding equipment –
Part 6: Limited duty equipment
Matériel de soudage à l’arc –
Partie 6: Matériel à service limité
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IEC 60974-6 ®
Edition 2.0 2010-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Arc welding equipment –
Part 6: Limited duty equipment
Matériel de soudage à l’arc –
Partie 6: Matériel à service limité
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
W
CODE PRIX
ICS 25.160.30 ISBN 978-2-88912-265-3
– 2 – 60974-6 Ó IEC:2010
CONTENTS
FOREW ORD . 6
1 Sc o pe . 8
2 Normative references . 8
3 Terms and definitions . 9
4 Environmental conditions. 10
5 Tests . 10
5.1 Test conditions . 10
5.2 Measuring instruments. 10
5.3 Conformity of components. 10
5.4 Type tests . 10
5.5 Routine tests . 11
6 Protection against electric shock . 11
6.1 Insulation . 11
6.1.1 General . 11
6.1.2 Clearances . 11
6.1.3 Creepage distances. 11
6.1.4 Insulation resistance. 12
6.1.5 Dielectric strength . 12
6.2 Protection against electric shock in normal service (direct contact). 12
6.2.1 Protection provided by the enclosure . 12
6.2.2 Capacitors . 12
6.2.3 Automatic discharge of input capacitors . 13
6.3 Protection against electric shock in case of a fault condition (indirect contact) . 13
6.3.1 Protective provisions . 13
6.3.2 Isolation of the supply circuit and the welding circuit . 13
6.3.3 Insulation between windings of the supply circuit and the welding
circuit . 13
6.3.4 Internal conductors and connections . 13
6.3.5 Additional requirements for plasma cutting systems . 13
6.3.6 Movable coils and cores. 13
6.3.7 Touch current in fault condition . 13
7 Thermal requirements . 15
7.1 Devices for thermal protection and thermal control . 15
7.2 Heating test . 15
7.2.1 Test conditions . 15
7.2.2 Tolerances of the test parameters . 15
7.2.3 Rated maximum welding current . 15
7.2.4 Calculation . 16
7.3 Temperature measurement . 16
7.3.1 Measurement condition . 16
7.3.2 Surface temperature sensor . 16
7.3.3 Resistance . 16
7.3.4 Embedded temperature sensor . 16
7.3.5 Determination of the ambient air temperature . 16
7.3.6 Recording of temperatures . 16
7.4 Limits of temperature . 16
60974-6 Ó IEC:2010 – 3 –
7.4.1 Windings, commutators and slip-rings . 16
7.4.2 External surfaces . 17
7.4.3 Other components . 17
7.5 Loading test . 17
7.6 Commutators and slip-rings . 17
8 Thermal control device . 18
8.1 Construction . 18
8.2 Location . 18
8.3 Operation . 18
8.4 Resetting . 18
8.5 Operating capacity . 18
8.6 Indication . 18
9 Thermal protection . 19
9.1 Construction . 19
9.2 Location . 19
9.3 Operation . 19
10 Abnormal operation . 19
10.1 General requirements . 19
10.2 Stalled fan test. 20
10.3 Short circuit test . 20
10.4 Overload test . 20
11 Connection to the input supply network . 20
11.1 Input supply . 20
11.1.1 Supply voltage . 20
11.1.2 Supply current . 20
11.1.3 Engine driven welding power source . 20
11.2 Multi supply voltage . 21
11.3 Means of connection to the supply circuit . 21
11.4 Supply circuit terminals . 21
11.5 Cable anchorage . 21
11.6 Inlet openings . 21
11.7 Supply circuit on/off switching device . 21
11.8 Supply cables . 21
11.9 Supply coupling device (attachment plug) . 21
12 Output . 22
12.1 Rated no-load voltage . 22
12.1.1 Rated no-load voltage for arc welding power source . 22
12.1.2 Rated no-load voltage for plasma cutting power source . 22
12.1.3 Additional requirements . 23
12.1.4 Measuring circuit . 23
12.2 Type test values of the conventional load voltage . 25
12.2.1 Manual metal arc welding with covered electrodes . 25
12.2.2 Tungsten inert gas . 25
12.2.3 Metal inert/active gas and flux cored arc welding . 25
12.2.4 Plasma cutting . 25
12.2.5 Additional requirements . 25
12.3 Mechanical switching devices used to adjust output . 25
12.4 Welding circuit connections . 25
– 4 – 60974-6 Ó IEC:2010
12.4.1 Protection against unintentional contact . 25
12.4.2 Location of coupling devices . 25
12.4.3 Outlet openings. 25
12.4.4 Marking . 25
12.4.5 Connections for plasma cutting torches . 25
12.5 Power supply to external devices . 25
12.6 Auxiliary power output . 26
12.7 Welding cables . 26
13 Control circuits . 26
14 Hazard reducing device . 26
15 Mechanical provisions . 27
15.1 General requirements . 27
15.2 Enclosure . 27
15.2.1 Enclosure materials . 27
15.2.2 Enclosure strength . 27
15.3 Handling means . 27
15.4 Drop withstand . 27
15.5 Tilting stability . 27
16 Auxiliaries . 27
16.1 General . 27
16.2 Wire feeder . 27
16.2.1 General . 27
16.2.2 Test conditions . 27
16.2.3 Thermal requirements . 27
16.2.4 Protection against unintentional contact . 27
16.3 Torch . 28
16.3.1 General . 28
16.3.2 Test conditions . 28
16.3.3 Thermal requirements . 28
16.4 Electrode holder. 28
16.5 Pressure regulator . 28
17 Rating plate . 28
17.1 General requirements . 28
17.2 Description . 28
17.3 Contents . 29
17.4 Tolerances . 31
18 Adjustment of the output . 31
19 Instructions and markings . 31
19.1 Instructions . 31
19.1.1 General . 31
19.1.2 Instruction manual . 32
19.1.3 Safety instructions . 32
19.2 Markings . 33
Annex A (informative) Test probes . 34
Annex B (informative) Examples of rating plates . 35
Annex C (informative) Symbols-only precautionary label . 36
Bibliography . 37
60974-6 Ó IEC:2010 – 5 –
Figure 1 – Measurement of touch current in fault condition . 14
Figure 2 – Measuring network for weighted touch current . 14
Figure 3 – Measurement of r.m.s values . 24
Figure 4 – Measurement of peak values . 24
Figure 5 – Principle of the rating plate . 29
Figure A.1 – Test probe 12 of IEC 61032 . 34
Figure A.2 – Test probe 13 of IEC 61032 . 34
Figure B.1 – Rating plate . 35
Figure C.1 – Example of precautionary label for engine driven manual metal arc
welding power sourceBibliography . 36
Table 1 – Temperature limits according to the class of insulation. 17
Table 2 – Summary of rated no-load voltages . 23
Table 3 – Hazard reducing device requirements for plasma cutting power source . 26
– 6 – 60974-6 Ó IEC:2010
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ARC WELDING EQUIPMENT –
Part 6: Limited duty equipment
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
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
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6) All users should ensure that they have the latest edition of this publication.
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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 60974-6 has been prepared by IEC technical committee 26:
Electric welding.
This second edition cancels and replaces the first edition published in 2003. It constitutes a
technical revision.
The main significant technical changes with respect to the previous edition are the following:
– extension of the scope;
– amendment of the title;
– touch current at fault condition (see 6.3.7);
– new definition of thermal requirements based two independent devices, one for thermal
protection and one for thermal control (see 7.1);
– new definition for thermal performances at 20 °C (see 7.2);
– thermal safety requirements are based on operating temperature for normal condition and
maximum temperature in overload condition (see 7.4);
60974-6 Ó IEC:2010 – 7 –
– addition of abnormal operation test for thermal control device (see 10.4);
– new requirement for auxiliaries (see Clause 16);
– new rating plate definition (see Clause 17);
– introduction of new mandatory warning symbols (see 12.1.117.3, Box 17b) and 19.2);
– induced changes due to publication of IEC 60974-1:2005.
The text of this standard is based on the following documents:
FDIS Report on voting
26/429/FDIS 26/437/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.
This standard is to be used in conjunction with IEC 60974-1:2005.
In this standard, the following print types are used:
– conformity statements: in italic type.
A list of all the parts in the IEC 60974 series, published under the general title Arc welding
equipment, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability 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.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.
– 8 – 60974-6 Ó IEC:2010
ARC WELDING EQUIPMENT –
Part 6: Limited duty equipment
1 Scope
This part of IEC 60974 specifies safety and performance requirements applicable to limited
duty arc welding and cutting power sources, and auxiliaries designed for use by laymen.
Electrically powered equipment is intended to be connected to the single phase public low-
voltage supply system. Engine driven power sources can not exceed output power of 7,5 kVA.
NOTE 1 This equipment is typically used by non-professionals in residential areas.
This part of IEC 60974 is not applicable to arc welding and cutting power sources that require
for operation:
· arc striking and stabilizing devices;
· liquid cooling systems;
· gas consoles;
· three-phase input supply;
and which are intended for industrial and professional use only.
This part of IEC 60974 is not applicable to arc welding and cutting power sources and
ancillary equipment used in:
· mechanically guided applications;
· submerged arc welding process;
· plasma gouging process;
· plasma welding process;
that are covered by other parts of IEC 60974.
NOTE 2 Power sources, wire feeders, torches and electrode holders designed for industrial and professional use
are respectively covered by IEC 60974-1, IEC 60974-5, IEC 60974-7 and IEC 60974-11.
NOTE 3 This part of IEC 60974 does not specify electromagnetic compatibility (EMC) requirements that are given
in IEC 60974-10.
2 Normative references
The following normative 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 60529, Degrees of protection provided by enclosures (IP Code)
IEC 60974-1:2005, Arc welding equipment – Part 1: Welding power sources
IEC 60974-5, Arc welding equipment – Part 5: Wire feeders
IEC 60974-7, Arc welding equipment – Part 7: Torches
60974-6 Ó IEC:2010 – 9 –
IEC 60974-10, Arc welding equipment – Part 10: Electromagnetic compatibility (EMC)
requirements
IEC 60974-11, Arc welding equipment – Part 11: Electrode holders
IEC 61032:1997, Protection of persons and equipment by enclosure – Probes for verification
ISO 2503, Gas welding equipment – Pressure regulators and pressure regulators with flow-
metering devices for gas cylinders used in welding, cutting and allied processes up to 300 bar
(30 MPa)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60974-1, as well as
the following apply:
3.1
touch current
electric current passing through a human body or through an animal body when it touches one
or more accessible parts of an installation or equipment
[IEC 60050-195, Amendment 1:2001, 195-05-21]
3.2
limited duty welding power source
power source intended for use by a layman
3.3
layman
operator who does not weld in the performance of his profession and has little or no formal
instruction in arc welding
3.4
effective supply current
I
1eff
value of the effective input current, calculated from the rated maximum supply current
(I in A), the supply current at no-load (I in A) and the rated maximum welding time in
1max 0
intermittent mode ( in s) at the rated maximum welding current during an uninterrupted
t
ON
å
time of one hour by the formula:
æ ö
t t
å å
2 ON 2 ON
ç ÷
I = I ´ + I ´ 1-
1eff 1max 0
ç ÷
3600 3600
è ø
3.5
ON time
t
ON
period of welding operation as allowed by the thermal control device of the welding power
source
3.6
OFF time
t
OFF
period of non-welding operation as imposed by the thermal control device of the welding
power source
– 10 – 60974-6 Ó IEC:2010
3.7
rated welding time in 1 h
t
å
ON
summation of the ON times (t ) at the rated maximum welding current in a 60 min period
ON
following the first OFF time (t )
OFF
3.8
rated continuous welding time
t (max)
ON
ON time (t ) at the rated maximum welding current before the first OFF time (t )
ON OFF
4 Environmental conditions
Welding power sources and auxiliaries shall be capable of operating when the following
environmental conditions prevail:
a) range of ambient air temperature:
during operation: –10 °C to +40 °C;
b) relative humidity of the air:
up to 50 % at 40 °C;
up to 90 % at 20 °C;
c) ambient air, free from abnormal amounts of dust, acids, corrosive gases or substances
etc. other than those generated by the welding process;
d) altitude above sea level up to 1 000 m;
e) base of the welding power source inclined up to 10°.
Welding power sources and auxiliaries shall withstand storage and transport at an ambient air
temperature of –20 °C to +55 °C without any damage to function and performance.
Welding power source and auxiliaries shall be capable of delivering the rated continuous
welding time and the rated welding time in 1 hour at an ambient temperature of 20 °C.
5 Tests
5.1 Test conditions
The thermal tests shall be carried out at an ambient temperature of 20 °C, see tolerances
in 7.2.2 e).
Other tests shall be carried out at an ambient air temperature between 10 °C and 40 °C.
5.2 Measuring instruments
See 5.2 of IEC 60974-1.
5.3 Conformity of components
See 5.3 of IEC 60974-1.
5.4 Type tests
Unless otherwise specified, the tests in this standard are type tests.
The welding power source shall be tested with any ancillary equipment fitted that could affect
the test results.
60974-6 Ó IEC:2010 – 11 –
All type tests shall be carried out on the same welding power source except where it is
specified that a test may be carried out on another welding power source.
As a condition of conformity the type tests given below shall be carried out in the following
sequence with no drying time between f),g) and h):
a) general visual inspection, see 3.7 of IEC 60974-1:2005;
b) insulation resistance, see 6.1.4 (preliminary check);
c) enclosure, see 15.2;
d) handling means, see 15.3;
e) drop withstand, see 15.4;
f) protection provided by the enclosure, see 6.2.1;
g) insulation resistance, see 6.1.4;
h) dielectric strength, see 6.1.5;
i) visual inspection, see 3.7 of IEC 60974-1:2005.
The other tests included in this standard and not listed in 5.4 shall be carried out in any
convenient sequence.
5.5 Routine tests
All routine tests shall be carried out on each welding power source. The following sequence is
recommended:
a) visual inspection, see 3.7 of IEC 60974-1:2005;
b) continuity of the protective circuit, see 10.4.2 of IEC 60974-1:2005;
c) dielectric strength, see 6.1.5;
d) no-load voltage
1) rated no-load voltage, see 12.1; or
2) for plasma cutting power source, rated reduced no-load voltage, see 13.2 of
IEC 60974-1:2005;
e) test to ensure rated minimum and maximum output values in accordance with 15.4 b) and
15.4 c) of IEC 60974-1:2005. The manufacturer may select conventional load, short circuit
load or other test conditions;
NOTE In short circuit and other test condition, the output values may differ from conventional load values.
6 Protection against electric shock
6.1 Insulation
6.1.1 General
See 6.1.1 of IEC 60974-1:2005.
6.1.2 Clearances
See 6.1.2 of IEC 60974-1:2005.
6.1.3 Creepage distances
See 6.1.3 of IEC 60974-1:2005.
– 12 – 60974-6 Ó IEC:2010
6.1.4 Insulation resistance
See 6.1.4 of IEC 60974-1:2005.
6.1.5 Dielectric strength
See 6.1.5 of IEC 60974-1:2005.
6.2 Protection against electric shock in normal service (direct contact)
6.2.1 Protection provided by the enclosure
6.2.1.1 General
Welding power sources shall have a minimum degree of protection of IP21S using IEC 60529
test procedures and conditions.
Remote controls for welding power sources shall have a minimum degree of protection of
IP2X using IEC 60529 test procedures and conditions.
6.2.1.2 Protection against ingress of water
Adequate drainage shall be provided by the enclosure. Retained water shall not interfere with
the correct operation of the equipment or impair safety.
Conformity shall be checked as follows:
A welding power source shall be subjected to the appropriate water test without being
energized. Immediately after the test, the welding power source shall be moved to a safe
environment and subjected to the insulation resistance and dielectric strength tests.
Adequate drainage of the enclosure shall be checked by visual inspection.
6.2.1.3 Side and top enclosure openings
The enclosure shall be such that a 50 mm long test pin cannot be inserted from all sides
except the underside to touch:
a) live parts of the input circuit or
b) in the case of Class II welding power sources, any metal part which is separated from live
parts of the input circuit by basic insulation.
Conformity shall be checked with test probe 12 of IEC 61032:1997 (see Figure A.1).
6.2.1.4 Bottom enclosure openings
The enclosure shall be such that a 15 mm long test pin cannot be inserted from the underside
to touch:
a) live parts of the input circuit and
b) in the case of Class II welding power sources, any metal part which is separated from live
parts of the input circuit by basic insulation.
Conformity shall be checked with test probe 13 of IEC 61032:1997 (see Figure A.2).
6.2.2 Capacitors
See 6.2.2 of IEC 60974-1:2005.
60974-6 Ó IEC:2010 – 13 –
6.2.3 Automatic discharge of input capacitors
See 6.2.3 of IEC 60974-1:2005.
6.3 Protection against electric shock in case of a fault condition (indirect contact)
6.3.1 Protective provisions
See 6.3.1 of IEC 60974-1:2005.
6.3.2 Isolation of the supply circuit and the welding circuit
See 6.3.2 of IEC 60974-1:2005.
6.3.3 Insulation between windings of the supply circuit and the welding circuit
See 6.3.3 of IEC 60974-1:2005.
6.3.4 Internal conductors and connections
See 6.3.4 of IEC 60974-1:2005.
6.3.5 Additional requirements for plasma cutting systems
See 6.3.5 of IEC 60974-1:2005.
6.3.6 Movable coils and cores
See 6.3.6 of IEC 60974-1:2005.
6.3.7 Touch current in fault condition
The weighted touch current shall not exceed 7 mA peak in the case of external protective
conductor failure or disconnection.
Conformity shall be checked using the measuring circuit as shown in Figure 1 and Figure 2
under the following conditions:
a) the welding power source is:
– isolated from the ground plane;
– supplied by the highest rated supply voltage;
– not connected to the protective earth except through measurement components;
b) the output circuit is in the no-load condition;
c) interference suppression capacitors shall not be disconnected.
NOTE Caution! A qualified person should perform this test. The protective conductor is disabled for this test.
– 14 – 60974-6 Ó IEC:2010
PE
N/L L
A
I I I
PE Out In
B
IEC 2582/10
Key
1 measuring network
2 power source
3 circuit diagram of Figure 2
A, B connection terminals of measuring network
L line
N neutral
PE protective earth
Figure 1 – Measurement of touch current in fault condition
R C
S S
A
R
B
C U
R U
B 1 1 2
IEC 2583/10
Key
A, B test terminals C
0,22 mF
S
R R
1 500 W 10 000 W
S 1
R 500 W C 0,022 mF
B 1
U r.m.s. voltage
weighted touch current (perception/reaction)
U
= (peak value)
Figure 2 – Measuring network for weighted touch current
60974-6 Ó IEC:2010 – 15 –
7 Thermal requirements
7.1 Devices for thermal protection and thermal control
A welding power source with limited duty shall be fitted with two independent devices, one for
thermal protection and one for thermal control.
The thermal control device limits the temperature of its components by opening the circuits or
by reducing the currents, and is reset automatically and is designed in accordance with
Clause 8.
The thermal protection defined in Clause 9 shall be designed to operate if the thermal control
device fails.
7.2 Heating test
7.2.1 Test conditions
The welding power source shall be operated at the rated maximum welding current I and
2max
conventional load voltage given in 12.2, starting from the cold state.
If it is known that I does not give the maximum heating, then a worst case test shall
2max
additionally be made at the setting within the rated range which gives the maximum heating.
When placing the measuring devices, the only access permitted shall be through openings
with cover plates, inspection doors or easily removable panels provided by the manufacturer.
The ventilation in the test area and the measuring devices used shall not interfere with the
normal ventilation of the welding power source or cause abnormal transfer of heat to or from
it.
NOTE 1 The maximum temperature of components may be reached at the no-load condition.
NOTE 2 The rated maximum welding current test and the relevant worst case test may follow each other without
waiting for the welding power source to return to the ambient air temperature.
7.2.2 Tolerances of the test parameters
During the heating test in accordance with 7.2.3 the following tolerances shall be met:
+10
a) load voltage: % of the appropriate conventional load voltage;
-5
+10
b) welding current: % of the appropriate conventional welding current;
-5
c) supply voltage: ±5 % of the appropriate rated supply voltage;
+10
d) engine speed: % of the appropriate rated speed;
-5
+10
e) temperature: K of the ambient temperature;
- 0
7.2.3 Rated maximum welding current
The test sequence for the rated maximum welding current I shall be as follows:
2max
a) Ensure that the welding power source is at thermal equilibrium with the ambient
temperature of 20 °C, see tolerances in 7.2.2 e).
b) Operate the power source at the rated maximum welding current.
– 16 – 60974-6 Ó IEC:2010
c) Record ON time until first operation of the thermal control device: rated continuous
welding time .
t (max)
ON
d) Continue the test immediately after the thermal control device resets, for a duration of
60 min.
e) Record ON time for each cycle .
t
ON
The test has failed if is less than 30 s or is less than 60 s.
t t (max)
ON
ON
7.2.4 Calculation
The following rated value shall be calculated:
· rated welding time in 1 hour at the rated maximum welding current see 7.2.3 e);
t
å
ON
where is the ON time for each cycle.
t
ON
The minimum value of shall be 60 s.
t
å ON
7.3 Temperature measurement
7.3.1 Measurement condition
The peak temperature shall be determined as follows:
a) For windings, by measurement of the resistance or embedded temperature sensor;
b) For other parts, by surface temperature sensor.
The peak temperature shall be measured during the last ON time of the 60 min heating test.
NOTE The design of limited duty power sources is based on a thermal control device that operates at the
maximum allowed temperature as defined by the insulation class.
7.3.2 Surface temperature sensor
See 7.2.2 of IEC 60974-1:2005.
7.3.3 Resistance
See 7.2.3 of IEC 60974-1:2005.
7.3.4 Embedded temperature sensor
See 7.2.4 of IEC 60974-1:2005.
7.3.5 Determination of the ambient air temperature
See 7.2.5 of IEC 60974-1:2005.
7.3.6 Recording of temperatures
See 7.2.6 of IEC 60974-1:2005.
7.4 Limits of temperature
7.4.1 Windings, commutators and slip-rings
The temperature for windings, commutators and slip-rings shall not exceed the operating
temperatures given in Table 1 for the class of insulation.
60974-6 Ó IEC:2010 – 17 –
No
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