IEC 62551:2012

Analysis techniques for dependability - Petri net techniques

IEC 62551:2012 provides guidance on a Petri net based methodology for dependability purposes. It supports modelling a system, analysing the model and presenting the analysis results. This methodology is oriented to dependability-related measures with all the related features, such as reliability, availability, production availability, maintainability and safety (e.g. safety integrity level (SIL) [2] related measures). Key words: Petri net based methodology for dependability purposes

Techniques d'analyse de sûreté de fonctionnement - Techniques des réseaux de Petri

La CEI 62551:2012 donne des directives pour une technique basée sur les réseaux de Petri dans le domaine de la sûreté de fonctionnement. Elle porte sur la modélisation d'un système, l'analyse du modèle et la présentation des résultats de l'analyse. Cette méthode est orientée vers les mesures relatives à la sûreté de fonctionnement avec toutes les caractéristiques associées, telles que la fiabilité, la disponibilité, la disponibilité de production, la maintenabilité et la sécurité (par exemple, les mesures associées au niveau d'intégrité de sécurité (SIL[2]: en anglais:system integrity level). Mots clés: technique basée sur les réseaux de Petri dans le domaine de la sûreté de fonctionnement

General Information

• Status: Published
• Publication Date: 01-Oct-2012
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 21.020 - Characteristics and design of machines, apparatus, equipment
• Technical Committee: TC 56 - Dependability
• Current Stage: PPUB - Publication issued
• Start Date: 31-Oct-2012
• Completion Date: 02-Oct-2012

Standards Content (Sample)

IEC 62551 ®
Edition 1.0 2012-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Analysis techniques for dependability – Petri net techniques

Techniques d'analyse de sûreté de fonctionnement – Techniques des réseaux
de Petri
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IEC 62551 ®
Edition 1.0 2012-10
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Analysis techniques for dependability – Petri net techniques

Techniques d'analyse de sûreté de fonctionnement – Techniques des réseaux

de Petri
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XB
ICS 21.020 ISBN 978-2-83220-370-5

– 2 – 62551 © IEC:2012
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms, definitions, symbols and abbreviations . 8
3.1 Terms and definitions . 8
3.2 Symbols and abbreviations . 10
4 General description of Petri nets . 12
4.1 Untimed low-level Petri nets . 12
4.2 Timed low-level Petri nets . 12
4.3 High-level Petri nets . 13
4.4 Extensions of Petri nets and modelling with Petri nets . 13
4.4.1 Further representations of Petri net elements . 13
4.4.2 Relationship to the concepts of dependability . 14
5 Petri net dependability modelling and analysis. 15
5.1 The steps to be performed in general . 15
5.2 Steps to be performed in detail . 16
5.2.1 General . 16
5.2.2 Description of main parts and functions of the system (Step 1) . 16
5.2.3 Modelling the structure of the system on the basis of Petri net-
submodels and their relations (Step 2). 16
5.2.4 Refining the models of Step 2 until the required level of detail is
achieved (Step 3) . 18
5.2.5 Analysing the model to achieve the results of interest (Step 4) . 18
5.2.6 Representation and interpretation of results of analyses (Step 5) . 19
5.2.7 Summary of documentation (Step 6) . 20
6 Relationship to other dependability models . 20
Annex A (informative) Structure and dynamics of Petri nets . 22
Annex B (informative) Availability with redundancy m-out-of-n . 33
Annex C (informative) Abstract example . 39
Annex D (informative) Modelling typical dependability concepts . 43
Annex E (informative) Level-crossing example . 45
Bibliography . 62

Figure 1 – Weighted inhibitor arc . 13
Figure 2 – Place p is a multiple place . 14
Figure 3 – Marking on p after firing of transition t . 14
Figure 4 – The activation of t depends on the value of V . 14
Figure 5 – Methodology consisting mainly of ‘modelling’, ‘analysing’ and ‘representing’
steps. 15
Figure 6 – Process for dependability modelling and analysing with Petri nets . 15
Figure 7 – Modelling structure concerning the two main parts 'plant' and 'control' with
models for their functions and dependability . 17
Figure 8 – Indication of the analysis method as a function of the PN model . 19

62551 © IEC:2012 – 3 –
Figure A.1 – Availability state-transition circle of a component . 22
Figure A.2 – Transition ‘failure’ is enabled . 23
Figure A.3 – ‘Faulty’ place marked due to firing of ‘failure' . 23
Figure A.4 – Transition ‘comp repair’ is enabled . 24
Figure A.5 – The token at the ‘maintenance crew available’ location is not used . 24
Figure A.6 – Transition is not enabled . 25
Figure A.7 – Marking before firing . 25
Figure A.8 – Marking after firing . 25
Figure A.9 – PN with initial marking . 25
Figure A.10 – Corresponding RG . 25
Figure A.11 – Transitions ‘comp repair’ and ‘comp failure’ are enabled . 26
lp hp
Figure A.12 – Marking after firing of transition ‘comp repair’ . 27
lp
Figure A.13 – A timed PN with two exponentially distributed timed transitions . 28
Figure A.14 – The corresponding stochastic reachability graph . 28
Figure A.15 – Petri net with timed transitions . 29
Figure B.1 – Two individual item availability nets with specific failure- and repair-rates . 33
Figure B.2 – Stochastic reachability graph corresponding to Figure B.1 with global
states (as an abbreviation c is used for “comp faulty”) . 33
1 1
Figure B.3 – Three individual item availability nets with specific failure rates and repair
rates . 33
Figure B.4 – Stochastic reachability graph corresponding to Figure B.3 with global
states (as an abbreviation c is used for ‘comp faulty’) . 34
Figure B.5 – Specifically connected 1-out-of-3 availability net . 35
Figure B.6 – Specifically connected 2-out-of-3 availability net . 35
Figure B.7 – Specifically connected 3-out-of-3 availability net . 36
Figure B.8 – Stochastic reachability graph with system specific operating states . 36
Figure B.9 – Specifically connected 1-out-of-3 reliability net . 37
Figure B.10 – Reachability graph for the net in Figure B.9 . 37
Figure B.11 – Specifically connected 2-out-of-3 reliability net . 37
Figure B.12 – Reachability graph for the net in Figure B.11 . 37
Figure B.13 – Specifically connected 3-out-of-3 reliability net . 38
Figure B.14 – Reachability graph for the net in Figure B.13 . 38
Figure C.1 – Individual availability net . 39
Figure C.2 – Stochastic availability graph of the net in Figure C.1 with its global states
and aggregated global states according to availability and safety . 39
Figure C.3 – Basic reliability and function modelling concept . 40
Figure C.4 – General hierarchical net with supertransitions to model reliability . 41
Figure C.5 – General hierarchical net with supertransitions and superplaces . 41
Figure C.6 – Gene
...