Arc welding equipment - Part 2: Liquid cooling systems

IEC 60974-2:2019 specifies safety and construction requirements for industrial and professional liquid cooling systems used in arc welding and allied processes to cool torches.
This document is applicable to liquid cooling systems which are stand-alone (separate from the welding equipment) or built-in (housed in a single enclosure with other welding equipment).
This fourth edition cancels and replaces the third edition published in 2013 and constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) changes induced by the publication of IEC 60974-1:2017;
b) reference in 11.1 changed.

Matériel de soudage à l'arc - Partie 2: Systèmes de refroidissement par liquide

L'IEC 60974-2:2019 spécifie les exigences de sécurité et de construction des systèmes de refroidissement par liquide industriels et professionnels utilisés en soudage à l'arc et les procédés connexes pour refroidir des torches.
Le présent document s'applique aux systèmes de refroidissement par liquide qui sont indépendants (séparés du matériel de soudage) ou incorporés (intégrés dans une seule enveloppe avec d’autres matériels de soudage).
Cette quatrième édition annule et remplace la troisième édition parue en 2013. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) modifications résultant de la publication de l’IEC 60974-1:2017;
b) référence au 11.1 modifiée.

General Information

Status
Published
Publication Date
29-Jan-2019
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
30-Jan-2019
Ref Project

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IEC 60974-2
Edition 4.0 2019-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Arc welding equipment –
Part 2: Liquid cooling systems
Matériel de soudage à l’arc –
Partie 2: Systèmes de refroidissement par liquide
IEC 60974-2:2019-01(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 60974-2
Edition 4.0 2019-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Arc welding equipment –
Part 2: Liquid cooling systems
Matériel de soudage à l’arc –
Partie 2: Systèmes de refroidissement par liquide
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.160.30 ISBN 978-2-8322-6497-3

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 60974-2:2019 © IEC 2019
CONTENTS

FOREWORD ........................................................................................................................... 4

1 Scope .............................................................................................................................. 6

2 Normative references ...................................................................................................... 6

3 Terms and definitions ...................................................................................................... 6

4 Environmental conditions ................................................................................................. 7

5 Tests ............................................................................................................................... 7

5.1 Test conditions ....................................................................................................... 7

5.2 Measuring instruments ............................................................................................ 7

5.3 Conformity of components ...................................................................................... 7

5.4 Type tests ............................................................................................................... 7

5.5 Routine tests........................................................................................................... 7

6 Protection against electric shock ..................................................................................... 8

6.1 Insulation ................................................................................................................ 8

6.1.1 General ........................................................................................................... 8

6.1.2 Clearances ...................................................................................................... 8

6.1.3 Creepage distances ......................................................................................... 8

6.1.4 Insulation resistance ........................................................................................ 8

6.1.5 Dielectric strength ............................................................................................ 8

6.2 Protection against electric shock in normal service (direct contact) ......................... 8

6.3 Protection against electric shock in case of a fault condition (indirect

contact) .................................................................................................................. 8

6.3.1 Protective provisions ....................................................................................... 8

6.3.2 Isolation between windings of the supply circuit and the welding circuit ........... 8

6.3.3 Internal conductors and connections ................................................................ 8

6.3.4 Touch current in fault condition ........................................................................ 8

6.4 Connection to the supply network ........................................................................... 8

6.4.1 Supply voltage ................................................................................................. 8

6.4.2 Multi-supply voltage ......................................................................................... 9

6.4.3 Means of connection to the supply circuit ........................................................ 9

6.4.4 Marking of terminals ........................................................................................ 9

6.4.5 Protective circuit .............................................................................................. 9

6.4.6 Cable anchorage ............................................................................................. 9

6.4.7 Inlet openings .................................................................................................. 9

6.4.8 Supply circuit on/off switching device ............................................................... 9

6.4.9 Supply cables .................................................................................................. 9

6.4.10 Supply coupling device (attachment plug) ........................................................ 9

6.5 Leakage current between welding circuit and protective earth ................................. 9

7 Mechanical provisions ................................................................................................... 10

7.1 General ................................................................................................................. 10

7.2 Cooling liquid overflow .......................................................................................... 10

7.3 Hose coupling devices and hose connections ....................................................... 10

8 Cooling system .............................................................................................................. 10

8.1 Rated maximum pressure ..................................................................................... 10

8.2 Thermal requirements ........................................................................................... 11

8.2.1 Heating test ................................................................................................... 11

8.2.2 Tolerances of test parameters ....................................................................... 11

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IEC 60974-2:2019 © IEC 2019 – 3 –

8.2.3 Duration of test .............................................................................................. 11

8.3 Pressure and temperature ..................................................................................... 11

9 Abnormal operation ....................................................................................................... 11

9.1 General requirements ........................................................................................... 11

9.2 Stalled test............................................................................................................ 12

10 COOLING POWER ............................................................................................................. 12

11 Rating plate ................................................................................................................... 13

11.1 General ................................................................................................................. 13

11.2 Description ........................................................................................................... 13

11.3 Contents ............................................................................................................... 14

11.4 Tolerances ............................................................................................................ 15

12 Instructions and markings .............................................................................................. 15

12.1 Instructions ........................................................................................................... 15

12.2 Markings ............................................................................................................... 16

12.2.1 General ......................................................................................................... 16

12.2.2 Inlet and outlet ............................................................................................... 16

12.2.3 Pressure warning ........................................................................................... 16

Annex A (informative) Example diagram of built-in and stand-alone LIQUID COOLING

SYSTEMS ................................................................................................................................ 17

Annex B (informative) Example for a rating plate of stand-alone cooling system ................... 18

Figure 1 – Leakage current measurement configuration ........................................................ 10

Figure 2 – Measuring circuit for determination of the COOLING POWER .................................... 13

Figure 3 – Principle of the rating plate of stand-alone cooling systems .................................. 14

Figure A.1 – Example diagram of built-in LIQUID COOLING SYSTEMS ......................................... 17

Figure A.2 – Example diagram of stand-alone LIQUID COOLING SYSTEMS ................................. 17

Figure B.1 – Single-phase stand-alone cooling unit ............................................................... 18

Table 1 – Example of cooling liquid data at 60 °C ................................................................. 13

---------------------- Page: 5 ----------------------
– 4 – IEC 60974-2:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ARC WELDING EQUIPMENT –
Part 2: Liquid cooling systems
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

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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

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between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

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 60974-2 has been prepared by IEC technical committee 26:

Electric welding.

This fourth edition cancels and replaces the third edition published in 2013 and constitutes a

technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) changes induced by the publication of IEC 60974-1:2017;
b) reference in 11.1 changed.
---------------------- Page: 6 ----------------------
IEC 60974-2:2019 © IEC 2019 – 5 –
The text of this International Standard is based on the following documents:
FDIS Report on voting
26/670/FDIS 26/675/RVD

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

In this standard, the following print types are used:
– conformity statements: in italic type.

– terms used throughout this standard which have been defined in clause 3: SMALL ROMAN

CAPITALS.
This document shall be used in conjunction with IEC 60974-1:2017.

A list of all parts of IEC 60974, under the general title Arc welding equipment, can be found

on the IEC web site.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 7 ----------------------
– 6 – IEC 60974-2:2019 © IEC 2019
ARC WELDING EQUIPMENT –
Part 2: Liquid cooling systems
1 Scope

This part of IEC 60974 specifies safety and construction requirements for industrial and

professional LIQUID COOLING SYSTEMS used in arc welding and allied processes to cool torches.

This document is applicable to LIQUID COOLING SYSTEMS which are stand-alone (separate from

the welding equipment) or built-in (housed in a single enclosure with other welding

equipment).
This document is not applicable to refrigerated cooling systems.
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 that are given

in IEC 60974-10.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their

content constitutes requirements 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 60974-1:2017, Arc welding equipment – Part 1: Welding power sources
IEC 60974-7:2013, Arc welding equipment – Part 7: Torches

IEC 60974-10:2014, Arc welding equipment – Part 10: Electromagnetic compatibility (EMC)

requirements
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60974-1 and

IEC 60974-7 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
cooling power
power related to the coolant flow rate and temperature rise
3.2
liquid cooling system

system that circulates and cools liquid used for decreasing the temperature of torches

---------------------- Page: 8 ----------------------
IEC 60974-2:2019 © IEC 2019 – 7 –
3.3
cooling power at 1 l/min
1 l/min
COOLING POWER at 1 l/min flow rate defined for comparison
4 Environmental conditions
As specified in Clause 4 of IEC 60974-1:2017.
5 Tests
5.1 Test conditions
As specified in 5.1 of IEC 60974-1:2017.
Stand-alone cooling systems may be tested without a welding power source.
Built-in cooling systems shall be tested with the welding power source.
5.2 Measuring instruments
The accuracy of measuring instruments shall be:

a) electrical measuring instruments: class 1 (± 1 % of full-scale reading), except for the

measurement of insulation resistance and dielectric strength where the accuracy of the

instruments is not specified, but shall be taken into account for the measurement;

b) thermometer: ± 2 K;
c) pressure measuring instruments: class 2,5 (± 2,5 % of full-scale reading);
d) flow-rate measuring instruments: class 2,5 (± 2,5 % of full-scale reading).
5.3 Conformity of components
As specified in 5.3 of IEC 60974-1:2017.
5.4 Type tests

All type tests shall be carried out on the same cooling system unless specified otherwise.

As a condition of conformity the type tests given below shall be carried out in the following

sequence:
a) general visual inspection (as defined in 3.1.7 of IEC 60974-1:2017);
b) mechanical provisions (as specified in Clause 7);

c) protection provided by the enclosure (as specified in 6.2.1 of IEC 60974-1:2017);

d) insulation resistance (as specified in 6.1.4);
e) dielectric strength (as specified in 6.1.5).

The other tests included in this document and not listed here may be carried out in any

convenient sequence.
5.5 Routine tests

All routine tests given below shall be carried out on each cooling system in the following

sequence:
a) visual inspection in accordance with manufacturer’s specification;
---------------------- Page: 9 ----------------------
– 8 – IEC 60974-2:2019 © IEC 2019

b) continuity of the protective circuit (as specified in 10.5.3 of IEC 60974-1:2017);

c) dielectric strength (as specified in 6.1.5).
6 Protection against electric shock
6.1 Insulation
6.1.1 General
As specified in 6.1.1 of IEC 60974-1:2017.
6.1.2 Clearances
As specified in 6.1.2 of IEC 60974-1:2017.
6.1.3 Creepage distances
As specified in 6.1.3 of IEC 60974-1:2017.
6.1.4 Insulation resistance
As specified in 6.1.4 of IEC 60974-1:2017.
The test may be carried out without cooling liquid.
6.1.5 Dielectric strength
As specified in 6.1.5 of IEC 60974-1:2017.
The test may be carried out without cooling liquid.
6.2 Protection against electric shock in normal service (direct contact)
As specified in 6.2 of IEC 60974-1:2017.

6.3 Protection against electric shock in case of a fault condition (indirect contact)

6.3.1 Protective provisions
As specified in 6.3.1 of IEC 60974-1:2017.
6.3.2 Isolation between windings of the supply circuit and the welding circuit
As specified in 6.3.2 of IEC 60974-1:2017.
6.3.3 Internal conductors and connections
As specified in 6.3.3 of IEC 60974-1:2017.
6.3.4 Touch current in fault condition
As specified in 6.3.6 of IEC 60974-1:2017.
6.4 Connection to the supply network
6.4.1 Supply voltage
As specified in 10.1 of IEC 60974-1:2017.
---------------------- Page: 10 ----------------------
IEC 60974-2:2019 © IEC 2019 – 9 –
6.4.2 Multi-supply voltage
As specified in 10.2 of IEC 60974-1:2017.
6.4.3 Means of connection to the supply circuit
As specified in 10.3 of IEC 60974-1:2017.
6.4.4 Marking of terminals
As specified in 10.4 of IEC 60974-1:2017.
6.4.5 Protective circuit
As specified in 10.5 of IEC 60974-1:2017.
6.4.6 Cable anchorage
As specified in 10.6 of IEC 60974-1:2017.
6.4.7 Inlet openings
As specified in 10.7 of IEC 60974-1:2017.
6.4.8 Supply circuit on/off switching device
As specified in 10.8 of IEC 60974-1:2017.
6.4.9 Supply cables
As specified in 10.9 of IEC 60974-1:2017.
6.4.10 Supply coupling device (attachment plug)

If a supply coupling device is provided as a part of the LIQUID COOLING SYSTEM, its rated values

shall be not less than the maximum effective supply current I .
1eff

For supply networks up to 125 V, the rated current shall, additionally, not be less than either

a) or b):
a) 70 % of the rated maximum supply current;

b) 70 % of the supply current, as measured with the fan motor or pump stalled, whichever is

greater.
Conformity shall be checked by visual inspection, measurement and calculation.
6.5 Leakage current between welding circuit and protective earth

With the cooling system filled with the cooling liquid specified by the manufacturer

(see 12.1 e)), the leakage current from the torch to the protective earth connection of the

cooling system shall not exceed 10 mA DC.

Conformity shall be checked by applying a DC voltage of 500 V at room temperature between

the protective earth connection and a copper pipe to simulate the torch connected to the

outlet of the cooling system by a hose with a maximum length of 0,5 m as shown in Figure 1.

The minimum inner diameter of the hose shall be 5 mm. The minimum length of the copper

pipe shall be 10 cm with a minimum internal diameter of 5 mm. The cooling system and the

simulated torch are filled with liquid for the test. The pump is operating.
---------------------- Page: 11 ----------------------
– 10 – IEC 60974-2:2019 © IEC 2019

NOTE The design of the torch can influence the leakage current value; therefore, a conventional copper pipe is

used to simulate the torch during the conformity test.
Key
1 LIQUID COOLING SYSTEM
2 Hose
3 Copper pipe
Figure 1 – Leakage current measurement configuration
7 Mechanical provisions
7.1 General
As specified in Clause 14 of IEC 60974-1:2017.
The test shall be carried out with cooling liquid.
7.2 Cooling liquid overflow

When filling the cooling system in accordance with the manufacturer's instructions, overflow

or spillage shall not result in electric shock.

Conformity shall be checked by the following treatment and test. The liquid container is

completely filled. A further quantity of liquid equal to 15 % of the capacity of the container or

0,25 l, whichever is the greater, is then poured in steadily over a period not to exceed 60 s.

Immediately after this treatment, the equipment shall pass the dielectric strength test of 6.1.5

between input circuits and exposed conductive parts.
7.3 Hose coupling devices and hose connections

If hose coupling devices or hose connections, which often have to be undone, are placed

above or near to live parts, these live parts shall be protected from cooling liquid by splash

proof enclosures, with drains or other appropriate measures. An exception is made for live

parts of the welding circuit.
8 Cooling system
8.1 Rated maximum pressure

The manufacturer shall determine the rated maximum pressure attainable by the cooling

system (see 11.3 c), box 12).

Conformity shall be checked by measuring the pressure when the outlet is blocked.

---------------------- Page: 12 ----------------------
IEC 60974-2:2019 © IEC 2019 – 11 –
8.2 Thermal requirements
8.2.1 Heating test

LIQUID COOLING SYSTEMS shall be capable of operating at rated COOLING POWER without

causing any component to exceed its rated temperature.
Conformity shall be checked in accordance with Clause 10.
8.2.2 Tolerances of test parameters
+10 %
a) p pressure: p
−2 %
+10 %
b) q volume flow: q
v −2 %
c) T temperature: T ± 2 K
8.2.3 Duration of test
As specified in 7.1.3 of IEC 60974-1:2017.
8.3 Pressure and temperature

LIQUID COOLING SYSTEMS shall be capable of operating without leakage at the maximum

pressure with a cooling liquid temperature of 70 °C.

Conformity shall be checked by visual inspection during 120 s of operation or until shutdown

by a protection system, immediately following the heating test while the outlet of the cooling

system is blocked.
9 Abnormal operation
9.1 G
...

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