Basic standard for the evaluation of human exposure to electromagnetic fields from equipment for resistance welding and allied processes

This European Standard applies to equipment for resistance welding and allied processes designed for use in industrial or domestic environments. NOTE 1 Typical allied processes are resistance hard and soft soldering or resistance heating achieved by means comparable to resistance welding equipment. This European Standard establishes a suitable evaluation method for determining the electromagnetic fields in the space around the equipment and defines standardized operating conditions and measuring distances. It provides a method to show conformity with guidelines or requirements concerning human exposure to electromagnetic fields. The Directive 2006/95/EC of the European Parliament and the Council [1], Article 2, stipulates that the Member States take all appropriate measures to ensure that electrical equipment may be placed on the market only if, having been constructed in accordance with good engineering practice in safety matters in force in the Community, it does not endanger the safety of persons, domestic animals or property when properly installed and maintained and used in applications for which is was made. The principal elements of those safety objectives are listed in Annex I Clause 2.b. This standard may be used in conjunction with EN 50445 for demonstration of conformity to the Council Directive with reference to human exposure to electromagnetic fields (EMF). There are additional requirements covered by Article 2 and Annex I Clause 2.b, which are not included in this document. The Council Recommendation 1999/519/EC [2] provides Basic Restrictions and Derived reference levels for exposure of the general public. This standard may be used for demonstration of resistance welding equipment conformity to the Council Recommendation on this basis, but there may be additional specific national or international requirements which are not included. The ICNIRP Guidelines [3], on limits of exposure to static magnetic fields as well as for limiting exposure in time varying electric, magnetic and electromagnetic fields, provide Basic restrictions and Derived reference levels for both occupational and general exposure. This standard may be used for demonstration of equipment conformity to ICNIRP Guidelines on this basis, but there may be additional national or international requirements which are not included. It is also possible to use this document as a basis to demonstrate conformity of resistance welding equipment to other national and international guidelines or requirements with regard to human exposure from EMF, for example Council Directive 2004/40/EC [4] on the minimum health and safety requirements regarding the exposure of workers to the risk arising from physical agents (electromagnetic fields), or the requirements of the Directive 98/37/EC [5]. In these cases, other restrictions and levels than those referenced above may be used. Other standards may apply to equipment covered by this standard. In particular this standard can not be used to demonstrate electromagnetic compatibility with other equipment; nor does it specify any product safety requirements other than those specifically related to human exposure to electromagnetic fields. The frequency range covered is 0 Hz to 300 GHz.

Grundnorm für die Bewertung der menschlichen Exposition gegenüber elektromagnetischen Feldern von Einrichtungen zum Widerstandsschweißen und für verwandte Verfahren

Diese Norm gilt für Einrichtungen zum Widerstandsschweißen und für verwandte Verfahren für die Verwendung in gewerblichen oder privaten Bereichen. ANMERKUNG 1 Typische verwandte Verfahren sind Widerstands-Hart- und Weichlöten oder Widerstandserwärmen mit Mitteln, die mit Einrichtungen zum Widerstandsschweißen vergleichbar sind. Diese Norm legt geeignete Verfahren zur Bewertung elektromagnetischer Felder in den die Einrichtung umgebenden Bereichen fest und definiert genormte Betriebsbedingungen und Bewertungsabstände. Sie stellt Verfahren bereit, mit denen die Konformität mit Richtlinien oder Anforderungen in Bezug auf die Exposition von Personen gegenüber elektromagnetischen Feldern festgestellt werden kann. Die Richtlinie des Europäischen Parlaments und des Rates 2006/95/EG [1], Artikel 2, legt fest, dass die Mitgliedstaaten alle zweckdienlichen Maßnahmen treffen, damit die elektrischen Betriebsmittel nur dann in Verkehr gebracht werden können, wenn sie, entsprechend dem in der Gemeinschaft gegebenen Stand der Sicherheitstechnik, so hergestellt sind, dass sie bei einer ordnungsgemäßen Installation und Wartung sowie einer bestimmungsgemäßen Verwendung die Sicherheit von Menschen und Nutztieren sowie die Erhaltung von Sachwerten nicht gefährden. Die Hauptelemente dieser Sicherheitsziele sind in Anhang I, Abschnitt 2.b aufgeführt. Diese Norm kann in Zusammenhang mit EN 50445 zum Nachweis der Übereinstimmung mit der Richtlinie des Rates in Bezug auf die Exposition von Personen gegenüber elektromagnetischen Feldern (EMF) verwendet werden. Artikel 2 und Anhang I Abschnitt 2.b enthalten weitere Anforderungen, die von diesem Dokument nicht abgedeckt sind. Die Empfehlung des Rates 1999/519/EG [2] enthält Basisgrenzwerte und abgeleitete Referenzwerte für die Exposition der Allgemeinbevölkerung. Diese Norm kann zum Nachweis der Übereinstimmung der Einrichtungen mit der Empfehlung des Rates auf dieser Grundlage verwendet werden, es gibt jedoch möglicherweise zusätzliche spezielle nationale oder internationale Anforderungen, die nicht einbezogen wurden. Die ICNIRP Richtlinien [3] zu Expositionsgrenzen für statische Magnetfelder sowie für Expositionsbegrenzung in zeitabhängig veränderlichen elektrischen, magnetischen und elektromagnetischen Feldern enthalten Basisgrenzwerte und abgeleitete Referenzwerte für berufsbedingte und allgemeine Exposition. Diese Norm kann dazu verwendet werden, die Übereinstimmung von Einrichtungen mit den ICNIRP Richtlinien auf dieser Grundlage zu zeigen, es kann aber zusätzliche nationale oder internationale Anforderungen geben, die nicht einbezogen wurden. Es ist auch möglich, dieses Dokument als Grundlage zum Nachweis der Übereinstimmung von Widerstandsschweißeinrichtungen mit anderen nationalen oder internationalen Richtlinien oder Anforderungen in Bezug auf Exposition von Menschen gegenüber EMF zu verwenden, z.B. die Richtlinie des Rates 2004/40/EG [4] über Mindestvorschriften zum Schutz von Sicherheit und Gesundheit der Arbeitnehmer vor der Gefährdung durch physikalische Einwirkungen (elektromagnetische Felder) oder die Anforderungen der Richtlinie 98/37/EG [5]. In diesen Fällen können andere Beschränkungen und Grenzwerte verwendet werden als die oben angegebenen. Für Einrichtungen, für die diese Norm gilt, können weitere Normen anwendbar sein. Im Besonderen ist diese Norm weder dafür vorgesehen, elektromagnetische Verträglichkeit mit anderen Einrichtungen nachzuweisen, noch spezifiziert sie andere Produktsicherheitsanforderungen als jene, die sich speziell auf die Exposition von Personen durch elektromagnetische Felder beziehen. Der abgedeckte Frequenzbereich ist 0 Hz bis 300 GHz. ANMERKUNG 2 Konformitätsnachweisverfahren sind nicht für den gesamten Frequenzbereich festgelegt.

Norme de base destinée à l’évaluation de l’exposition humaine aux champs électromagnétiques émanant du matériel de soudage par résistance et des techniques connexes

Osnovni standard za oceno izpostavljenosti ljudi elektromagnetnim sevanjem opreme za uporovno varjenje in sorodne procese

General Information

Status
Withdrawn
Publication Date
17-Apr-2008
Technical Committee
Drafting Committee
Parallel Committee
Current Stage
6060 - Document made available
Due Date
18-Apr-2008
Completion Date
18-Apr-2008

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SLOVENSKI STANDARD
SIST EN 50505:2008
01-september-2008
Osnovni standard za oceno izpostavljenosti ljudi elektromagnetnim sevanjem
opreme za uporovno varjenje in sorodne procese

Basic standard for the evaluation of human exposure to electromagnetic fields from

equipment for resistance welding and allied processes
Grundnorm für die Bewertung der menschlichen Exposition gegenüber
elektromagnetischen Feldern von Einrichtungen zum Widerstandsschweißen und für
verwandte Verfahren
Norme de base destinée à l’évaluation de l’exposition humaine aux champs

électromagnétiques émanant du matériel de soudage par résistance et des techniques

connexes
Ta slovenski standard je istoveten z: EN 50505:2008
ICS:
13.280 Varstvo pred sevanjem Radiation protection
25.160.10 Varilni postopki in varjenje Welding processes
SIST EN 50505:2008 en,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 50505:2008
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SIST EN 50505:2008
EUROPEAN STANDARD
EN 50505
NORME EUROPÉENNE
April 2008
EUROPÄISCHE NORM
ICS 25.160.30
English version
Basic standard for the evaluation
of human exposure to electromagnetic fields
from equipment for resistance welding
and allied processes
Norme de base destinée à l’évaluation Grundnorm für die Bewertung
de l’exposition humaine der menschlichen Exposition gegenüber
aux champs électromagnétiques émanant elektromagnetischen Feldern
du matériel de soudage par résistance von Einrichtungen zum Widerstands-
et des techniques connexes schweißen und für verwandte Verfahren

This European Standard was approved by CENELEC on 2008-03-01. 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 50505:2008 E
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SIST EN 50505:2008
EN 50505:2008 - 2 -
Foreword

This European Standard was prepared by the Technical Committee CENELEC TC 26B, Electric

resistance welding.

The text of the draft was submitted to the formal vote and was approved by CENELEC as EN 50505

on 2008-03-01.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
(dop) 2009-03-01
national standard or by endorsement
– latest date by which the national standards conflicting
(dow) 2011-03-01
with the EN have to be withdrawn
This European Standard shall be read in conjunction with EN 50445.

This European Standard has been prepared under mandates M/305 and M/351 given to CENELEC by

the European Commission and the European Free Trade Association.
__________
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SIST EN 50505:2008
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Contents

1 Scope ............................................................................................................................................... 5

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

3 Definitions ....................................................................................................................................... 6

3.1 General ................................................................................................................................... 6

3.2 Specific for resistance welding and similar applications ........................................................ 8

4 Physical quantities, units and constants ...................................................................................10

4.1 Quantities and units ..............................................................................................................10

4.2 Constants..............................................................................................................................10

5 Assessment procedures ..............................................................................................................10

5.1 General .................................................................................................................................10

5.2 Resistance welding equipment EMF emission description ..................................................10

5.3 Assessment conditions .........................................................................................................11

5.4 Averaging..............................................................................................................................11

5.5 Pulsed or non-sinusoidal welding current .............................................................................12

5.6 Conductivity of living tissue ..................................................................................................18

5.7 Frequency range limitations .................................................................................................18

5.8 Application of assessment procedures .................................................................................19

5.9 Measurements ......................................................................................................................21

5.10 Analytical calculations ..........................................................................................................23

5.11 Numerical calculations ..........................................................................................................28

6 Uncertainty of assessment ..........................................................................................................30

6.1 Including uncertainty .............................................................................................................30

6.2 Evaluation of uncertainties ...................................................................................................31

6.3 Reasonable overall uncertainties .........................................................................................31

6.4 Examples of typical uncertainties .........................................................................................32

7 Assessment report .......................................................................................................................32

7.1 General principles .................................................................................................................32

7.2 Items to be recorded in the assessment report ....................................................................33

Annex A (normative) Assessment parameters ..................................................................................34

Annex B (informative) Examples for exposure assessment ............................................................46

Annex C (informative) Numerical simulation using anatomical body models ...............................59

Annex D (normative) Determination of coupling factor ....................................................................63

Annex E (informative) Summation weighting and transfer function examples ..............................65

Annex F (informative) Example for an uncertainty budget ...............................................................70

Bibliography ..........................................................................................................................................71

Figures

Figure 1 – Example for parameters of a welding current sequence ..................................................... 12

Figure 2 – Average electrical conductivities for homogeneous body modelling from 10 Hz to

10 MHz ................................................................................................................................ 18

Figure 3 – Double parallel conductor model .......................................................................................... 25

Figure 4 – Rectangular conductor model .............................................................................................. 26

Figure A.1 – Points of investigation for stationary welding equipment .................................................. 35

Figure A.2 – Point of investigation for portable hand-held welding equipment ..................................... 36

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SIST EN 50505:2008
EN 50505:2008 - 4 -

Figure A.3 – Point of investigation for suspended welding equipment ................................................. 37

Figure A.4 – Point of investigation for a single side welding tool .......................................................... 38

Figure A.5 – Point of investigation for a double side welding tool ......................................................... 38

Figure A.6 – Simulation geometry for stationary equipment ................................................................. 40

Figure A.7 – Simulation geometry A ...................................................................................................... 41

Figure A.8 – Simulation geometry B ...................................................................................................... 42

Figure A.9 – Simulation geometry C ..................................................................................................... 43

Figure A.10 – Simulation geometry for single side welding tool equipment .......................................... 44

Figure A.11 – 3D models dimensions for spheroid and cylindrical models ........................................... 45

Figure B.1 – Flux density waveform and r.m.s. spectral components for summation........................... 48

Figure B.2 – Summation of ratios B / B including phases in the time domain ................................... 49

i L,i

Figure B.3 – Flux density waveform and r.m.s. spectral components for summation........................... 50

Figure B.4 – Current density distribution on disk diameter for f = 50 Hz............................................... 51

Figure B.5 – Summation of ratios J / J including phases in the time domain ..................................... 52

i L,i

Figure B.6 – Welding current and measured field waveform ................................................................ 53

Figure B.7 – Obtained flux density waveform and r.m.s. spectral components .................................... 55

Figure B.8 – Summation of ratios J / J including phases in the time domain ..................................... 56

i L,i

Figure B.9 – J spectral components summation including phases in the time domain......................... 56

Figure B.10 – Measurement sensor position......................................................................................... 57

Figure E.1 – Peak reference level transfer function and tabulated values ............................................ 66

Figure E.2 – B summation weighting function and phase tabulated values .......................................... 67

Figure E.3 – Peak basic restriction transfer function and tabulated values .......................................... 68

Figure E.4 – J summation weighting function and phase tabulated values .......................................... 69

Tables

Table 1 – Permissible assessment procedures for resistance welding equipment .............................. 19

Table 2 – Reasonable expanded assessment uncertainties ................................................................. 31

Table B.1 – Flux density spectral components...................................................................................... 47

Table B.2 – Flux density spectral components...................................................................................... 48

Table B.3 – Flux density spectral components...................................................................................... 49

Table B.4 – Flux density spectral components...................................................................................... 50

Table B.5 – Result of flux density spectral components summation ..................................................... 50

Table B.6 – Result of current density spectral components summation ............................................... 51

Table B.7 – Result of spectral components summation ........................................................................ 54

Table B.8 – Flux density and induced current spectral components .................................................... 55

Table C.1 – Electrical conductivity of tissue types ................................................................................ 61

Table F.1 – Example uncertainty budget for broadband field measurement ........................................ 70

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1 Scope

This European Standard applies to equipment for resistance welding and allied processes designed

for use in industrial or domestic environments.

NOTE 1 Typical allied processes are resistance hard and soft soldering or resistance heating achieved by means comparable

to resistance welding equipment.

This European Standard establishes a suitable evaluation method for determining the electromagnetic

fields in the space around the equipment and defines standardized operating conditions and

measuring distances. It provides a method to show conformity with guidelines or requirements

concerning human exposure to electromagnetic fields.

The Directive 2006/95/EC of the European Parliament and the Council [1], Article 2, stipulates that the

Member States take all appropriate measures to ensure that electrical equipment may be placed on

the market only if, having been constructed in accordance with good engineering practice in safety

matters in force in the Community, it does not endanger the safety of persons, domestic animals or

property when properly installed and maintained and used in applications for which is was made. The

principal elements of those safety objectives are listed in Annex I Clause 2.b. This standard may be

used in conjunction with EN 50445 for demonstration of conformity to the Council Directive with

reference to human exposure to electromagnetic fields (EMF). There are additional requirements

covered by Article 2 and Annex I Clause 2.b, which are not included in this document.

The Council Recommendation 1999/519/EC [2] provides Basic Restrictions and Derived reference

levels for exposure of the general public. This standard may be used for demonstration of resistance

welding equipment conformity to the Council Recommendation on this basis, but there may be

additional specific national or international requirements which are not included.

The ICNIRP Guidelines [3], on limits of exposure to static magnetic fields as well as for limiting

exposure in time varying electric, magnetic and electromagnetic fields, provide Basic restrictions and

Derived reference levels for both occupational and general exposure. This standard may be used for

demonstration of equipment conformity to ICNIRP Guidelines on this basis, but there may be

additional national or international requirements which are not included.

It is also possible to use this document as a basis to demonstrate conformity of resistance welding

equipment to other national and international guidelines or requirements with regard to human

exposure from EMF, for example Council Directive 2004/40/EC [4] on the minimum health and safety

requirements regarding the exposure of workers to the risk arising from physical agents

(electromagnetic fields), or the requirements of the Directive 98/37/EC [5]. In these cases, other

restrictions and levels than those referenced above may be used.

Other standards may apply to equipment covered by this standard. In particular this standard can not

be used to demonstrate electromagnetic compatibility with other equipment; nor does it specify any

product safety requirements other than those specifically related to human exposure to

electromagnetic fields.
The frequency range covered is 0 Hz to 300 GHz.

NOTE 2 Procedures to demonstrate conformity are not specified for the whole frequency range.

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EN 50505:2008 - 6 -
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 50392 2004 Generic standard to demonstrate the compliance of electronic and
electrical apparatus with the basic restrictions related to human
exposure to electromagnetic fields (0 Hz – 300 GHz)
EN 50445 2008 Product family standard to demonstrate compliance of equipment for
resistance welding, arc welding and allied processes with the basic
restrictions related to human exposure to electromagnetic fields
(0 Hz – 300 GHz)
EN 61566 1997 Measurement of exposure to radio-frequency electromagnetic
fields – Field strength in the frequency range 100 kHz to 1 GHz
(IEC 61566:1997)

EN 62226-1 2005 Exposure to electric or magnetic fields in the low and intermediate

frequency range – Methods for calculating the current density and
internal electric field induced in the human body – Part 1: General
(IEC 62226-1:2004)

EN 62226-2-1 2005 Exposure to electric or magnetic fields in the low and intermediate

frequency range – Methods for calculating the current density and
internal electric field induced in the human body – Part 2-1: Exposure
to magnetic fields – 2D models (IEC 62226-2-1:2004)

EN ISO/IEC 17025 2005 General requirements for the competence of testing and calibration

laboratories (ISO/IEC 17025:2005)
IEC 61786 1998 Measurement of low-frequency magnetic and electric fields with
regard to exposure of human beings – Special requirements for
instruments and guidance for measurements
ISO 669 2000 Resistance welding – Resistance welding equipment – Mechanical
and electrical requirements
3 Definitions
3.1 General
For the purposes of this document, the following terms and definitions apply.
3.1.1
averaging time (t )
avg

appropriate time over which exposure is averaged for purposes of determining conformity

3.1.2
basic restrictions

restrictions on exposure to electric, magnetic and electromagnetic fields that are based directly on

established health effects and biological considerations
3.1.3
compliance boundary

spatial border outside which any point of investigation is deemed to be compliant

3.1.4
conductivity (σ)

ratio of the conduction current density in a medium to the electric field strength

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SIST EN 50505:2008
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3.1.5
contact current

current flowing into the body by touching a conductive object in an electromagnetic field

3.1.6
coupling factor (K)

used to enable exposure assessment for complex exposure situations, such as non-uniform magnetic

field or perturbed electric field

NOTE The coupling factor K has different physical interpretations depending on whether it relates to electric or magnetic field

exposure. The value of the coupling factor K depends on the model used for the field source and the model used for the human

body.
3.1.7
effective reference level (B )
L,eff

level, provided for practical exposure assessment purposes using a broadband measurement, derived

from frequency dependent reference levels considering the spectral content of the field

3.1.8
EMF
electric, magnetic or electromagnetic field
3.1.9
exposure

situation that occurs when a person is subjected to electric, magnetic or electromagnetic fields or to

contact current other than those originating from physiological processes in the body and other natural

phenomena
3.1.10
exposure level

value of the quantity evaluated when a person is exposed to electromagnetic fields or contact currents

3.1.11
exposure, non-uniform

results when fields are non-uniform over volumes comparable to the whole human body

3.1.12
induced current density (J)
electromagnetic field induced current per unit area inside the body
3.1.13
magnetic field strength (H)

magnitude of a field vector in a point that results in a force ( F ) on a charge (q) moving with velocity

( v )
r r
F = q(v × µH )
(1)
or magnetic flux density divided by permeability of the medium
3.1.14
magnetic flux density (B)

magnitude of a field vector that is equal to the magnetic field strength (H) multiplied by the

permeability (µ) of the medium
B = µ H (2)
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SIST EN 50505:2008
EN 50505:2008 - 8 -
3.1.15
permeability (µ)

property of a material which defines the relationship between magnetic flux density (B) and magnetic

field strength (H)

NOTE 1 It is commonly used as the combination of the permeability of free space (µ ) and the relative permeability for

specific dielectric materials (µ ).
µ = µ µ (3)
R 0
NOTE 2 Permeability is expressed in henry per metre (H m ).
3.1.16
point of investigation (POI)

location in space at which the value of the E-field, H-field or power density is evaluated

NOTE This location is defined in Cartesian, cylindrical or spherical co-ordinates relative to the reference point on the EUT.

3.1.17
root-mean-square (r.m.s.)
effective value or the value associated with joule heating, of a periodic signal

NOTE The r.m.s. value is obtained by taking the square root of the mean of the squared value of a function.

x = x (t)dt
rms (expression in time domain) (4)
where x(t) is the signal at time t, T is the signal period or multiples of it
x = x
(expression in frequency domain) (5)
rms ∑ n

where x is the magnitude of spectral component at n frequency, expressed as r.m.s. value.

3.1.18
reference levels

directly measurable quantities, derived from basic restrictions, provided for practical exposure

assessment purposes

NOTE Respect of the reference level will ensure respect of the relevant basic restriction. If the reference level is exceeded, it

does not necessarily follow that the basic restriction will be exceeded.
3.1.19
response time

time required for field strength indicated by a measurement instrument to reach 90 % of its final value

when the instrument is exposed to a defined step function of field strength

NOTE This step function is defined as a change in field strength from less than 1 % of the full scale deflection (fsd) of the

measurement instrument to 100 % of fsd occurring in a time of 1/4 of the period of the waveform at the frequency of interest.

3.2 Specific for resistance welding and similar applications
3.2.1
conventional load
load condition with the electrodes short-circuiting as defined in ISO 669:2000
3.2.2
current flow time

duration defined from the start time of current conduction to the time when its current has decreased to

10 % level of the measured welding current value
3.2.3
duty factor (X)
ratio for a given interval of the on-load duration to the total time
NOTE This ratio, lying between 0 and 1, may be expressed as a percentage.
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3.2.4
equipment for resistance welding and allied processes

equipment associated with carrying out the processes of resistance welding or allied processes

consisting of e.g. power source, electrodes, tooling and associated control equipment, which may be a

separate unit or part of a complex machine
3.2.5
hand-held integrated transformer gun

resistance welding equipment with built-in transformer and all conductors carrying their welding

current, which is intended to be held in the hand during use
3.2.6
hand-held separated transformer gun

resistance welding equipment with separate transformer, which is intended to be held in the hand

during use
3.2.7
maximum short-circuit current output (I )
2cc

equipment rated output current with conventional load as defined in ISO 669:2000, Clause 10

3.2.8
phase control

typical current control technique in resistance welding, e.g. by changing the firing angle in each

half-weld cycle of a.c. current
3.2.9
processes allied to resistance welding

processes which are carried out on machines comparable to resistance welding equipment

NOTE Typical allied processes are resistance hard and soft soldering or resistance heating achieved by means comparable to

resistance welding equipment.
3.2.10
stationary resistance welding equipment

resistance welding equipment which is stationary, the operator handle the piece to be welded

3.2.11
suspended integrated transformer gun

resistance welding equipment with built-in transformer and all conductors carrying their welding

current, which is intended to be suspended and hand-guided by the operator to position the equipment

in the correct welding position
3.2.12
suspended separated transformer gun

resistance welding equipment with separate transformer, which is intended to be suspended and

hand-guided by the operator to position the equipment in the correct welding position

3.2.13
weld time

current flow time given as a number of cycles of the mains frequency or as time duration

3.2.14
welding cable(s)

flexible conductor(s) used to connect the power source and the welding tool in some types of

resistance welding equipment

NOTE Typical examples of these equipments are the car-body production and repair welding-station.

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EN 50505:2008 - 10 -
3.2.15
welding circuit

circuit that includes all conductive material through which the welding current is intended to flow

3.2.16
welding current

current value accumulated over the weld time and indicated by the r.m.s. value, which is applicable for

a.c. and d.c. current

NOTE In the case of pulsed current, e.g. a capacitor discharged current, the welding current is indicated by the peak value.

4 Physical quantities, units and constants
4.1 Quantities and units
The internationally accepted SI units are used throughout this document.
Quantity Symbol Unit Dimension
Current density J Ampere per square metre A m
Electric conductivity σ Siemens per metre S m
Frequency f Hertz Hz
Magnetic field strength H Ampere per metre A m
Magnetic flux density B Tesla T (Vs m )
Permeability µ Henry per metre H m
4.2 Constants
Physical constant Symbol Magnitude
-7 -1
Permeability of free space
µ 4π × 10 H m
5 Assessment procedures
5.1 General

This European Standard defines, as far as possible, suitable points of investigation for different types

of equipment that represent the highest exposure positions during practical use. These points of

investigation are based on previous experience and measurement, taking into account typical operator

positions, and have been selected to protect against effects on central nervous system tissues in the

head and trunk of the body.

NOTE 1 Equipment complying with the basic restriction or reference levels at the points of investigation defined in this

European Standard are considered to be compliant with the requirements of the reference document that contains limits.

NOTE 2 Equipment that does not comply with these tests needs to be carefully evaluated to quantify the exposure in all

relevant operator positions. This evaluation shall define compliance boundaries that describe all the operator positions that are

in conformity with the requirements. The equipment use shall be restricted according to the established compliance boundaries.

5.2 Resistance welding equipment EMF emission description

The main source of EMF in a resistance welding equipment is the welding current flowing through the

welding circuit, generating a low frequency magnetic field, this has the greatest influence on the

exposure level.
The emission is a non homogeneous field at the proximity of equipment.
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SIST EN 50505:2008
- 11 - EN 50505:2008

The parameters of the welding current (e.g. amplitude and waveform), and the welding circuit

characteristics (e.g. dimensions), are determined by the equipment only. External fa

...

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