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BS EN 60990:2016

BS EN 60990:2016

$198.66

Methods of measurement of touch current and protective conductor current

Published By Publication Date Number of Pages
BSI 2016 66
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This International Standard defines measurement methods for

  • d.c. or a.c. current of sinusoidal or non-sinusoidal waveform, which could flow through the human body, and

  • current flowing through a protective conductor.

The measuring methods recommended for touch current are based upon the possible effects of current flowing through a human body. In this standard, measurements of current through networks representing the impedance of the human body are referred to as measurements of touch current. These networks are not necessarily valid for the bodies of animals.

The specification or implication of specific limit values is not within the scope of this standard. IEC TS 60479 series provides information regarding the effects of current passing through the human body from which limit values may be derived.

This standard is applicable to all classes of equipment, according to IEC 61140 .

The methods of measurement in this standard are not intended to be used for

  • touch currents having less than 1 s duration,

  • patient currents as defined in IEC 60601‑1 ,

  • a.c. at frequencies below 15 Hz, and

  • currents above those chosen for electric burn limits.

This basic safety publication is primarily intended for use by technical committees in the preparation of standards in accordance with the principles laid down in IEC Guide 104 and ISO/IEC Guide 51 . It is not intended for use by manufacturers or certification bodies independent of product standards.

One of the responsibilities of a technical committee is, wherever applicable, to make use of basic safety publications in the preparation of its publications. The requirements, test methods or test conditions of this basic safety publication only apply when specifically referred to or included in the relevant publications.

PDF Catalog

PDF Pages PDF Title
4 European foreword
Endorsement notice
5 Annex ZA (normative) Normative references to international publications with their corresponding European publications
6 English
CONTENTS
10 FOREWORD
12 INTRODUCTION
14 1 Scope
2 Normative references
15 3 Terms and definitions
4 Test site
4.1 Test site environment
16 4.2 Test transformer
4.3 Earthed neutral conductor
Figures
Figure 1 – Example of earthed neutral, direct supply
17 5 Measuring equipment
5.1 Selection of measuring network
5.1.1 General
Figure 2 – Example of earthed neutral, with transformer for isolation
Figure 3 – Measuring network, unweighted touch current
18 5.1.2 Perception and startle-reaction
5.1.3 Letgo-immobilization
5.1.4 Electric burn (a.c.)
5.1.5 Ripple-free d.c.
Figure 4 – Measuring network, touch current weighted for perception or startle-reaction
Figure 5 – Measuring network, touch current weighted for letgo-immobilization
19 5.2 Test electrodes
5.2.1 Construction
5.2.2 Connection
5.3 Configuration
5.4 Power connections during test
5.4.1 General
20 Figure 6 – Single-phase equipment on star TN or TT system
Figure 7 – Single-phase equipment on centre-earthed TN or TT system
21 Figure 8 – Single-phase equipment connected line-to-line on star TN or TT system
Figure 9 – Single-phase equipment connected line-to-neutral on star IT system
Figure 10 – Single-phase equipment connected line-to-line on star IT system
22 Figure 11 – Three-phase equipment on star TN or TT system
Figure 12 – Three-phase equipment on star IT system
23 5.4.2 Equipment for use only on TN or TT star power distribution systems
5.4.3 Equipment for use on IT power distribution systems including unearthed delta systems
Figure 14 – Three-phase equipment on centre-earthed delta system
Figure 13 – Unearthed delta system
24 5.4.4 Equipment for use on single-phase centre-earthed power supply systems or on centre-earthed delta power supply systems
5.5 Supply voltage and frequency
5.5.1 Supply voltage
5.5.2 Supply frequency
6 Test procedure
6.1 General
6.1.1 Touch current measurements
25 6.1.2 Control switches, equipment and supply conditions
6.1.3 Use of measuring networks
6.2 Normal and fault conditions of equipment
6.2.1 Normal operation of equipment
6.2.2 Equipment and supply fault conditions
27 7 Evaluation of results
7.1 Perception, startle-reaction and letgo-immobilization
7.2 Electric burn
8 Measurement of protective conductor current
8.1 General
28 8.2 Multiple equipment
8.3 Measuring method
29 Annexes
Annex A (normative) Equipment
Figure A.1 – Equipment
30 Annex B (normative) Use of a conductive plane
Figure B.1 – Equipment platform
31 Annex C (normative) Incidentally connected parts
32 Annex D (informative) Choice of current limits
D.1 General
D.2 Limit examples
D.2.1 Ventricular fibrillation
D.2.2 Inability to letgo-immobilization
D.2.3 Startle-reaction
D.2.4 Perception threshold
D.2.5 Special applications
33 D.3 Choice of limits
34 D.4 Electric burn effects of touch current
35 Annex E (informative) Networks for use in measurement of touch current
E.1 General
E.2 Body impedance network – Figure 3
E.3 Startle-reaction (and body impedance) network – Figure 4
36 E.4 Letgo-immobilization (and body impedance) network – Figure 5
37 Annex F (informative) Measuring network limitations and construction
Figure F.1 – Frequency factor for electric burn
Figure F.2 – Frequency factor for perception or startle-reaction
38 Figure F.3 – Frequency factor for letgo-immobilization
39 Annex G (informative) Construction and application of touch current measuring instruments
G.1 Considerations for selection of components
G.1.1 General
G.1.2 Power rating and inductance for RS and RB
G.1.3 Capacitor CS
40 G.1.4 Resistors R1, R2 and R3
G.1.5 Capacitors C1, C2 and C3
G.2 Voltmeter
G.3 Accuracy
41 G.4 Calibration and application of measuring instruments
G.5 Records
G.6 Confirmation systems
43 Annex H (informative) Analysis of frequency filtered touch current circuit measurements
44 Figure H.1 – Triangular waveform touch current, startle-reaction
Tables
Table H.1 – Triangular waveform response comparison
45 Figure H.3 – 1 ms rise time pulse response, startle-reaction
Figure H.4 – 1 ms rise time pulse response, letgo-immobilization
Table H.2 – Square wave touch current response
46 Figure H.5 – Touch current vs. rise time plot, 20 ms square wave
Figure H.6 – PFC SMPS touch current waveform
47 Figure H.7 – 50 Hz square wave, 0,1 ms rise time, startle-reaction
Figure H.8 – 50 Hz square wave, 0,1 ms rise time, letgo-immobilization
Table H.3 – Square wave monopolar touch current response
48 Figure H.9 – IEC TS 60479-2 let-go threshold for AC and DC combinations augmented by additional data, mA each axis
49 Figure H.10 – Ex1 case: showing r.m.s. window
Figure H.11 – Waveform ex2 case: showing r.m.s. window
Table H.4 – Mixed ACnDC waveform evaluation, ex1
50 Table H.5 – Mixed ACnDC waveform evaluation, ex2
51 Annex I (informative) AC power distribution systems (see 5.4)
I.1 General
52 I.2 TN power systems
Figure I.1 – Examples of TN-S power system
53 Figure I.2 – Example of TN-C-S power system
Figure I.3 – Example of TN-C power system
54 I.3 TT power systems
Figure I.4 – Example of single-phase, 3-wire TN-C power system
Figure I.5 – Example of 3-line and neutral TT power system
55 I.4 IT power systems
Figure I.6 – Example of 3-line TT power system
Figure I.7 – Example of 3-line (and neutral) IT power system
56 Figure I.8 – Example of 3-line IT power system
57 Annex J (informative) Routine and periodic touch current tests, and tests after repair or modification of mains operated equipment
58 Annex K (normative) Network performance and calibration
K.1 Network or instrument performance and initial calibration
Table K.1 – Calculated input impedance and transfer impedancefor unweighted touch current measuring network (Figure 3)
59 Table K.2 – Calculated input impedance and transfer impedance for startle-reaction touch current measuring network (Figure 4)
Table K.3 – Calculated input impedance and transfer impedance for letgo-immobilization current measuring network (Figure 5)
60 K.2 Calibration in a confirmation system
K.2.1 General
K.2.2 Measurement of input resistance
K.2.3 Measurement of instrument performance
61 Table K.4 – Output voltage to input voltage ratios for unweighted touch current measuring network (Figure 3)
Table K.5 – Output voltage to input voltage ratios for startle-reaction measuring network (Figure 4)
62 Table K.6 – Output voltage to input voltage ratiosfor letgo-immobilization measuring network (Figure 5)
63 Bibliography

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BS EN 60990:2016
$198.66