IEC 62425:2007

Railway applications - Communication, signalling and processing systems - Safety related electronic systems for signalling

Applies to all safety-related railway signalling systems/sub-system/equipment. The hazard analysis and risk assessment processes defined in IEC 62278 and this standard are necessary for all railway signalling systems/sub-systems/equipment, in order to identify any safety requirements.

Applications ferroviaires - Systèmes de signalisation, de télécommunications et de traitement - Systèmes électroniques de sécurité pour la signalisation

Est applicable à tous les systèmes/sous-systèmes/équipements de signalisation ferroviaire relatifs à la sécurité. Les processus d'analyse des situations dangereuses et d'évaluation des risques définis dans la CEI 62278 et dans la présente norme sont nécessaires pour tous les systèmes/sous-systèmes/équipements de signalisation ferroviaire, de manière à identifier les exigences de sécurité.

General Information

• Status: Published
• Publication Date: 17-Sep-2007
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 45.060.01 - Railway rolling stock in general
• Technical Committee: TC 9 - Electrical equipment and systems for railways
• Current Stage: PPUB - Publication issued
• Start Date: 15-Oct-2007
• Completion Date: 18-Sep-2007

Standards Content (Sample)

IEC 62425
Edition 1.0 2007-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Railway applications – Communication, signalling and processing systems –
Safety related electronic systems for signalling

Applications ferroviaires – Systèmes de signalisation, de télécommunications et
de traitement – Systèmes électroniques de sécurité pour la signalisation

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IEC 62425
Edition 1.0 2007-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Railway applications – Communication, signalling and processing systems –
Safety related electronic systems for signalling

Applications ferroviaires – Systèmes de signalisation, de télécommunications et
de traitement – Systèmes électroniques de sécurité pour la signalisation

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
XD
CODE PRIX
ICS 45.060 ISBN 2-8318-9310-0
– 2 – 62425 © IEC:2007
CONTENTS
FOREWORD.5
INTRODUCTION.7

1 Scope.8
2 Normative references.9
3 Terms, definitions and abbreviations .10
3.1 Definitions .10
3.2 Abbreviations.15
4 Overall framework of this standard.16
5 Conditions for safety acceptance and approval.17
5.1 The safety case .17
5.2 Evidence of quality management.19
5.3 Evidence of safety management .21
5.3.1 Introduction .21
5.3.2 Safety life-cycle .22
5.3.3 Safety organisation .23
5.3.4 Safety plan .24
5.3.5 Hazard log .25
5.3.6 Safety requirements specification.25
5.3.7 System/sub-system/equipment design.25
5.3.8 Safety reviews .25
5.3.9 Safety verification and validation .25
5.3.10 Safety justification.26
5.3.11 System/sub-system/equipment handover.26
5.3.12 Operation and maintenance .26
5.3.13 Decommissioning and disposal .26
5.4 Evidence of functional and technical safety .26
5.5 Safety acceptance and approval .29
5.5.1 Introduction .29
5.5.2 Safety approval process.30
5.5.3 After safety approval.32
5.5.4 Dependency between safety approvals.32

Annex A (normative) Safety integrity levels .33
Annex B (normative) Detailed technical requirements .47
Annex C (normative) Identification of hardware component failure modes .62
Annex D (informative) Supplementary technical information.79
Annex E (informative) Techniques and measures for safety-related electronic systems
for signalling for the avoidance of systematic faults and the control of random and
systematic faults .86

Bibliography .95

Figure 1 – Scope of the main IEC railway application standards.9
Figure 2 – Structure of IEC 62425 .17

62425 © IEC:2007 – 3 –
Figure 3 – Structure of safety case .19
Figure 4 – Example of system life-cycle (from IEC 62278) .21
Figure 5 – Example of design and validation portion of system life-cycle .23
Figure 6 – Arrangements for independence .24
Figure 7 – Structure of technical safety report.29
Figure 8 – Typical safety acceptance and approval process .31
Figure 9 – Examples of dependencies between safety cases/safety approval .32
Figure A.1 – Safety requirements and safety integrity .34
Figure A.2 – Global process overview.36
Figure A.3 – Example risk analysis process .37
Figure A.4 – Definition of hazards with respect to the system boundary.38
Figure A.5 – Example hazard control process .40
Figure A.6 – Interpretation of failure and repair times .41
Figure A.7 – Treatment of functional independence by FTA .42
Figure A.8 – Relationship between SILs and techniques .45
Figure B.1 – Influences affecting the independence of items.52
Figure B.2 – Detection and negation of single faults.55
Figure C.1 – Example of a 4-terminal resistor, using a hybrid thick layer technique .65
Figure D.1 – Example of a fault analysis method .83

Table A.1 – SIL-table .45
Table C.1 – Resistors.68
Table C.2 – Capacitors.69
Table C.3 – Electromagnetic components.69
Table C.4 – Diodes .71
Table C.5 – Transistors.72
Table C.6 – Controlled rectifiers .73
Table C.7 – Surge suppressors .74
Table C.8 – Opto-electronic components .75
Table C.9 – Filters.76
Table C.10 – Interconnection assemblies .76
Table C.11 – Fuses.77
Table C.12 – Switches and push/pull buttons.77
Table C.13 – Lamps .77
Table C.14 – Batteries.78
Table C.15 – Transducers/sensors (not including those with internal electronic circuitry).78
Table C.16 – Integrated circuits.78
Table D.1 – Examples of measures to detect faults in large-scale integrated circuits by
means of periodic on-line testing, with comparison (SW or HW), in a 2-out-of-n system .
Table E.1 – Safety planning and quality assu
...