Industrial electroheating and electromagnetic processing equipment - Evaluation of hazards caused by magnetic nearfields from 1 Hz to 6 MHz

IEC/TS 62997:2017(E) specifies the characteristics of external magnetic nearfields, computations of and requirements on induced electric fields in body tissues in the frequency range from 1 Hz to 6 MHz with respect to induced electric shock phenomena, for electroheating (EH) based treatment technologies and for electromagnetic processing of materials (EPM). The phenomena include specific absorption rates with time integration.

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Status
Published
Publication Date
14-Jun-2017
Current Stage
PPUB - Publication issued
Start Date
15-Jun-2017
Completion Date
15-Jun-2017
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IEC TS 62997:2017 - Industrial electroheating and electromagnetic processing equipment - Evaluation of hazards caused by magnetic nearfields from 1 Hz to 6 MHz
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IEC TS 62997
Edition 1.0 2017-06
TECHNICAL
SPECIFICATION
colour
inside
Industrial electroheating and electromagnetic processing equipment –
Evaluation of hazards caused by magnetic nearfields from 1 Hz to 6 MHz
IEC TS 62997:2017-06(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TS 62997
Edition 1.0 2017-06
TECHNICAL
SPECIFICATION
colour
inside
Industrial electroheating and electromagnetic processing equipment –
Evaluation of hazards caused by magnetic nearfields from 1 Hz to 6 MHz
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 25.180.10 ISBN 978-2-8322-4449-4

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

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 62997:2017 © IEC 2017
CONTENTS

FOREWORD ........................................................................................................................... 7

INTRODUCTION ..................................................................................................................... 9

1 Scope ............................................................................................................................ 11

2 Normative references .................................................................................................... 11

3 Terms, definitions, symbols and abbreviated terms ........................................................ 11

3.1 Terms and definitions ............................................................................................ 11

3.2 Quantities and units .............................................................................................. 14

4 Organisation and use of the technical specification ........................................................ 15

5 The basic relationship for determination of the in situ induced electric field ................... 16

6 Requirements related to immediate nerve and muscle reactions .................................... 16

6.1 General ................................................................................................................. 16

6.2 Method using the conductor geometry and current restriction (CGCR) .................. 17

6.3 Volunteer test method ........................................................................................... 18

6.3.1 Volunteer basic test method .......................................................................... 18

6.3.2 Method based on volunteer tests and similarity with pre-existing

scenario ........................................................................................................ 19

6.3.3 Method based on volunteer tests, using available elevated conductor

current or shorter distance between the conductor and bodypart ................... 19

6.3.4 Method using magnetic nearfield reference levels (RLs) ................................ 19

7 Requirements related to body tissue overheating ........................................................... 19

7.1 General ................................................................................................................. 19

7.2 Intermittent conditions with 6 minutes time integration .......................................... 20

7.3 Intermittent conditions in fingers and hands with shorter integration times ............ 21

8 Calculations and numerical computations of induced E field and SAR by magnetic

nearfields: inaccuracies, uncertainties and safety factors .............................................. 21

8.1 Principles for handling levels of safety – general ................................................... 21

8.2 The C value variations with B field curvature ......................................................... 22

8.3 Location of parts of the body, instrumentation and measurement issues ............... 22

8.4 Handling of inaccuracies of in situ E field and SAR numerical values .................... 22

8.5 Approaches to compliance .................................................................................... 23

8.5.1 General ......................................................................................................... 23

8.5.2 Cases where verification of levels being below the RL is sufficient ................ 23

8.5.3 Cases where only B flux measurements are sufficient .................................... 23

8.5.4 Cases where the volunteer test method is applicable ..................................... 23

8.5.5 Cases where the CGCR method is applicable ................................................ 23

8.5.6 Cases where numerical modelling is carried out ............................................ 24

8.6 Summary of inaccuracy/uncertainty factors to be considered ................................ 24

9 Risk group classification and warning marking ............................................................... 24

9.1 General ................................................................................................................. 24

9.2 Induced electric fields from 1 Hz to 1 kHz ............................................................. 25

9.3 Induced electric fields from 1 kHz to 100 kHz ........................................................ 25

9.4 Induced electric fields from 100 kHz to 6 MHz ....................................................... 25

9.5 Magnetic flux fields from 1 Hz to 6 MHz ................................................................ 25

9.6 Warning marking ................................................................................................... 25

Annex A (informative) Survey of basic restrictions, reference levels in other

standards, etc. ...................................................................................................................... 27

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IEC TS 62997:2017 © IEC 2017 – 3 –

A.1 Basic restrictions – general and deviations ........................................................... 27

A.2 The coupling values C in ICNIRP guidelines and IEEE standards .......................... 27

A.3 Basic restrictions – immediate nerve and muscle reactions ................................... 28

A.4 Basic restrictions – specific absorption rates (SAR) .............................................. 29

A.5 Reference levels – external magnetic B field ......................................................... 29

Annex B (normative) Analytical calculations of magnetically induced internal E field

phenomena ........................................................................................................................... 30

B.1 Some basic formulas – magnetic fields and Laws of Nature .................................. 30

B.2 Induced field deposition in tissues by magnetic nearfields ..................................... 31

B.3 Coupling of a homogeneous B field to homogeneous objects with simple

geometries ............................................................................................................ 31

B.4 Starting points for numerical modelling ................................................................. 32

B.4.1 Relevant bodyparts ........................................................................................ 32

B.4.2 The use of external B field and internal power density in numerical

modelling ....................................................................................................... 32

Annex C (normative) Reference objects representing parts of the body: tissue

conductivities ........................................................................................................................ 33

C.1 Reference bodyparts ............................................................................................. 33

C.1.1 General ......................................................................................................... 33

C.1.2 The wrist/arm models .................................................................................... 33

C.1.3 The hand model with tight fingers .................................................................. 33

C.1.4 The hand model with spread-out fingers ........................................................ 33

C.1.5 The finger model............................................................................................ 33

C.2 Dielectric properties of human tissues ................................................................... 33

C.2.1 General data for assessments ....................................................................... 33

C.2.2 Inner parts of the body ................................................................................... 34

C.2.3 Skin data ....................................................................................................... 34

Annex D (informative) Results of numerical modelling with objects in a Helmholtz coil

and at a long straight conductor ............................................................................................ 35

D.1 General and a large Helmholtz coil scenario with a diameter 200 mm sphere

– FDTD 3D modelling ............................................................................................ 35

D.2 Other reference objects in the Helmholtz coil – FDTD 3D modelling ...................... 36

D.2.1 The scenario .................................................................................................. 36

D.2.2 Numerical modelling results with smaller spheres .......................................... 36

D.2.3 Numerical results with other objects .............................................................. 37

Annex E (informative) Numerical FDTD modelling with objects at a long straight wire

conductor .............................................................................................................................. 38

E.1 Scenario and general information .......................................................................... 38

E.2 Two 200 mm diameter spheres ............................................................................. 39

E.3 The hand model with tight fingers at different distances from the wire –

FDTD modelling .................................................................................................... 40

E.3.1 General information and scenario .................................................................. 40

E.3.2 Modelling results – power deposition patterns ................................................ 40

E.4 The hand model with tight fingers at 100 mm from the wire – Flux® 12 FEM

modelling .............................................................................................................. 42

E.5 Coupling data and analysis for the hand model with tight fingers above the

wire – FDTD modelling .......................................................................................... 42

E.6 Coupling data and analysis for the wrist/arm model above the wire ....................... 43

Annex F (informative) Numerical modelling and volunteer experiments with the hand

models at a coil..................................................................................................................... 45

F.1 General and on the B field amplitude .................................................................... 45

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– 4 – IEC TS 62997:2017 © IEC 2017
F.2 The hand model with tight fingers 2 mm, 4 mm, 6 mm and 50 mm above the

coil and with its right side above the coil axis – FDTD modelling ........................... 46

F.2.1 The scenario .................................................................................................. 46

F.2.2 Modelling results ........................................................................................... 47

F.3 The hand model with tight fingers 6 mm above the coil and with variable

position in the x direction – FDTD modelling ......................................................... 51

F.4 The hand model with spread-out fingers, 6 mm straight above the coil –

FDTD modelling .................................................................................................... 51

F.5 The hand model with tight fingers near a coil with metallic workload – FDTD

modelling .............................................................................................................. 52

F.6 The finger model 2 mm above the coil – FDTD numerical modelling ...................... 54

F.6.1 The scenarios ................................................................................................ 54

F.6.2 Modelling results ........................................................................................... 54

F.7 Analysis of the FDTD modelling results ................................................................. 56

F.7.1 General ......................................................................................................... 56

F.7.2 With the hand model ...................................................................................... 56

F.7.3 With the finger model ..................................................................................... 56

F.8 Volunteer studies .................................................................................................. 56

F.8.1 General ......................................................................................................... 56

F.8.2 Calculations of the induced electric field strength in F.7.1 .............................. 57

F.9 Comparisons with conventional electric shock effects by contact current .............. 57

F.10 Conclusions from the data in Annexes E and F ..................................................... 58

F.10.1 Coupling factor C data in relation to reference object geometries and

magnetic flux characteristics without workload ............................................... 58

F.10.2 Coupling factor C modifications by workloads ................................................ 58

F.10.3 Rationales for the CGCR basic value with the volunteer method .................... 58

Annex G (informative) Some examples of CGCR values of a hand near conductors as

function of frequency, conductor current and configuration ................................................... 60

G.1 Frequency and conductor current relationships: adopted CGCR value .................. 60

G.2 A hand above a thin wire ....................................................................................... 60

G.3 A hand above a coil .............................................................................................. 61

Annex H (informative) Frequency upscaling with numerical modelling .................................. 64

H.1 General and energy penetration depth .................................................................. 64

H.2 Actual penetration depth data ............................................................................... 64

H.3 The penetration depth issue of representativity with frequency upscaling .............. 65

H.4 Separation of the internal power density caused by direct capacitive

coupling, and that caused by the external magnetic field ....................................... 65

H.5 The frequency upscaling procedures ..................................................................... 66

H.5.1 General ......................................................................................................... 66

H.5.2 Choices of conductivity and control procedures ............................................. 66

Bibliography .......................................................................................................................... 68

Figure 1 – Examples of warning marking ............................................................................... 26

Figure A.1 – ICNIRP, IEEE and 2013/35/EU basic restrictions (RMS) ................................... 28

Figure D.1 – The z-directed magnetic field momentaneous maximal amplitude in the

central y plane of the Helmholtz coil with the conductive 200 mm diameter sphere ............... 36

Figure D.2 – The power density patterns in the central y plane (left) and central z

(equatorial) plane of the 200 mm diameter sphere ................................................................ 36

Figure D.3 – The power density patterns in the central z plane of the reference

objects, with maximal C values in m ...................................................................................... 37

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IEC TS 62997:2017 © IEC 2017 – 5 –

Figure E.1 – Long straight wire scenario ............................................................................... 38

Figure E.2 – Power deposition patterns in the central z planes of the two spheres at

10 mm and 20 mm away from the sphere axis; σ = 20 Sm ................................................. 39

Figure E.3 – Power deposition pattern in the central y plane of the sphere at 10 mm

distance from the wire axis; σ = 20 Sm .............................................................................. 39

Figure E.4 – Scenario with the hand model above the wire axis ............................................ 40

Figure E.5 – Power density in the hand model 2,5 mm above the wire axis ........................... 40

Figure E.6 – Power density in the hand model 14 mm above the wire axis ............................ 41

Figure E.7 – Power density in the hand model 100 mm above the wire axis .......................... 41

Figure E.8 – Current density in the central cross section of the hand model at 9 mm

from the wire – Flux® 12 FEM modelling ............................................................................... 42

Figure E.9 – Wrist/arm model above a long straight wire ....................................................... 43

Figure E.10 – Linear power density (left, power scaling) and electric field amplitude (linear

scale) in the x plane of wrist/arm model 10 mm straight above a long straight wire .............. 43

Figure F.1 – Illustration of the B field at a single turn coil, with the coil centre at the

left margin of the image – Flux® 12 FEM modelling .............................................................. 45

Figure F.2 – Hand above the coil scenario ............................................................................ 46

Figure F.3 – Power density pattern in the central vertical plane and in the bottom 1 mm

layer of the hand model, z = 2 mm above the top of the coil; a = –51 mm .............................. 47

Figure F.4 – Power density pattern in the central vertical plane and in the bottom 1 mm

layer of the hand model, z = 4 mm; a = –51 mm .................................................................... 47

Figure F.5 – Power density pattern in the central vertical plane and in the bottom

1 mm layer of the hand model, z = 50 mm; a = –51 mm ......................................................... 48

Figure F.6 – The ±x-directed (left image) and ±y-directed momentaneous maximal E

field at the hand underside, z = 4 mm; a = –51 mm ............................................................... 49

Figure F.7 – The local power density pattern of the condition in Figure F.3, showing the

1 mm × 1 mm voxel size and the 5 mm integration region 2 mm above the hand

underside .............................................................................................................................. 50

Figure F.8 – The local y-directed momentaneous maximal electric field pattern of the

condition in Figure F.3, showing the 1 mm × 1 mm voxel size and the 5 mm

integration region 2 mm above the hand underside ............................................................... 50

Figure F.9 – The power density pattern in the hand model centred above the coil and

6 mm above it; left image: bottom region, right image: 10 mm up .......................................... 51

Figure F.10 – The hand model with spread-out fingers located 6 mm straight above

the coil (left); relative power densities at the height of maximum power density

between fingers (right) .......................................................................................................... 51

Figure F.11 – The hand model 6 mm above the coil and a 100 mm diameter metallic

workload in the coil ............................................................................................................... 52

Figure F.12 – Quiver plot of the magnetic (H) field amplitude in logarithmic scaling, in

the scenario in Figure F.11 with a non-magnetic (left) and magnetic (right) workload ............ 52

Figure F.13 – The power density pattern in the central vertical cross section in the

hand scenario in Figure F.11 ................................................................................................ 53

Figure F.14 – The power density in the central vertical cross section of the hand as in

the scenario in Figure F.11, but 50 mm above the coil; with no workload (left) and with

permeable metallic workload (right) ...................................................................................... 53

Figure F.15 – The two finger positions above the coil; left = y-directed finger........................ 54

Figure F.16 – Power density maximum pattern in the y-directed 17 mm diameter finger

model ................................................................................................................................... 54

Figure F.17 – Power density maximum pattern in the x-directed 17 mm diameter finger

model ................................................................................................................................... 55

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– 6 – IEC TS 62997:2017 © IEC 2017

Figure F.18 – Momentaneous maximal electric field maximum pattern in the x-directed

17 mm diameter finger model ................................................................................................ 55

Figure F.19 – Plastic plate above the coil .............................................................................. 57

Figure G.1 – Allowed RMS current at 11 kHz, based on CGCR = 40 Vm ........................... 60

Figure G.2 – CGCR coil currents at 11 kHz for the hand model with the side at the coil

axis, at various heights above the coil ................................................................................... 62

Figure G.3 – CGCR coil currents at 11 kHz for the hand model at 6 mm above the coil

with different sideways positions ........................................................................................... 63

Table C.1 – Examples of dielectric data of human tissues at normal body temperature ........ 34

Table E.1 – Coupling factors for the hand model with tight fingers at various heights

above the wire axis ............................................................................................................... 42

Table G.1 – Coupling factors and allowed coil currents at 11 kHz for the hand model

with the side at the coil axis, at various heights above the coil .............................................. 61

Table G.2 – Coupling factors and allowed coil currents at 11 kHz for the hand model

at 6 mm above the coil with different sideways positions ....................................................... 62

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IEC TS 62997:2017 © IEC 2017 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL ELECTROHEATING AND
ELECTROMAGNETIC PROCESSING EQUIPMENT –
Evaluation of hazards caused by magnetic nearfields
from 1 Hz to 6 MHz
FOREWORD

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