BS EN 60990:2016 – TC:2020 Edition
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Tracked Changes. Methods of measurement of touch current and protective conductor current
| Published By | Publication Date | Number of Pages |
| BSI | 2020 | 145 |
IEC 60990:2016 is available as /2 which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition. IEC 60990:2016 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 third edition cancels and replaces the second edition published in 1999. It constitutes a technical revision. The principal changes in this edition as compared with the second edition are as follows: – the effects names have been updated to reflect increased understanding of the range of effects and is in concert with present usage; – the conditions of use invoking a GRIPPABLE PART have been reduced in the application of the requirements based upon the current understanding of this effect; – the references to ISO 10012-1, which has been replaced by management standard of the same number, have been replaced with explanatory text, where needed to maintain the sense of the document; – former informative Annex H (GRIPPABLE PART) has been deleted from this update as it does not properly represent the full set of conditions under which immobilization can occur. A new informative Annex H (Analysis of frequency filtered touch current circuits measurement) has been added and the Bibliography (formerly Annex M) has been updated with additional references for completeness. This basic safety publication is primarily intended for use by technical committees in the preparation of standards in accordance with /2 and ISO/IEC Guide 51. It is not intended for use by manufacturers or certification bodies independent of product standards. It has the status of a Basic Safety Publication in accordance with /2 Key words: Touch Current, Protective Conductor Current, Current Flow
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 83 | European foreword Endorsement notice |
| 84 | Annex ZA (normative) Normative references to international publications with their corresponding European publications |
| 85 | English CONTENTS |
| 89 | FOREWORD |
| 91 | INTRODUCTION |
| 93 | 1 Scope 2 Normative references |
| 94 | 3 Terms and definitions 4 Test site 4.1 Test site environment |
| 95 | 4.2 Test transformer 4.3 Earthed neutral conductor Figures Figure 1 – Example of earthed neutral, direct supply |
| 96 | 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 |
| 97 | 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 |
| 98 | 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 |
| 99 | Figure 6 – Single-phase equipment on star TN or TT system Figure 7 – Single-phase equipment on centre-earthed TN or TT system |
| 100 | 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 |
| 101 | Figure 11 – Three-phase equipment on star TN or TT system Figure 12 – Three-phase equipment on star IT system |
| 102 | 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 |
| 103 | 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 |
| 104 | 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 |
| 106 | 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 |
| 107 | 8.2 Multiple equipment 8.3 Measuring method |
| 108 | Annexes Annex A (normative) Equipment Figure A.1 – Equipment |
| 109 | Annex B (normative) Use of a conductive plane Figure B.1 – Equipment platform |
| 110 | Annex C (normative) Incidentally connected parts |
| 111 | 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 |
| 112 | D.3 Choice of limits |
| 113 | D.4 Electric burn effects of touch current |
| 114 | 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 |
| 115 | E.4 Letgo-immobilization (and body impedance) network – Figure 5 |
| 116 | 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 |
| 117 | Figure F.3 – Frequency factor for letgo-immobilization |
| 118 | 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 |
| 119 | G.1.4 Resistors R1, R2 and R3 G.1.5 Capacitors C1, C2 and C3 G.2 Voltmeter G.3 Accuracy |
| 120 | G.4 Calibration and application of measuring instruments G.5 Records G.6 Confirmation systems |
| 122 | Annex H (informative) Analysis of frequency filtered touch current circuit measurements |
| 123 | Figure H.1 – Triangular waveform touch current, startle-reaction Tables Table H.1 – Triangular waveform response comparison |
| 124 | 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 |
| 125 | Figure H.5 – Touch current vs. rise time plot, 20 ms square wave Figure H.6 – PFC SMPS touch current waveform |
| 126 | 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 |
| 127 | Figure H.9 – IEC TS 60479-2 let-go threshold for AC and DC combinations augmented by additional data, mA each axis |
| 128 | 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 |
| 129 | Table H.5 – Mixed ACnDC waveform evaluation, ex2 |
| 130 | Annex I (informative) AC power distribution systems (see 5.4) I.1 General |
| 131 | I.2 TN power systems Figure I.1 – Examples of TN-S power system |
| 132 | Figure I.2 – Example of TN-C-S power system Figure I.3 – Example of TN-C power system |
| 133 | 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 |
| 134 | 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 |
| 135 | Figure I.8 – Example of 3-line IT power system |
| 136 | Annex J (informative) Routine and periodic touch current tests, and tests after repair or modification of mains operated equipment |
| 137 | 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) |
| 138 | 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) |
| 139 | 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 |
| 140 | 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) |
| 141 | Table K.6 – Output voltage to input voltage ratiosfor letgo-immobilization measuring network (Figure 5) |
| 142 | Bibliography |
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