This document provides guidance on probabilistic risk analysis (hereafter referred to as risk analysis) for the systems composed of electrotechnical items and is applicable (but not limited) to all electrotechnical industries where risk analyses are performed.<\/p>\n
This document deals with the following topics from the perspective of risk analysis:<\/p>\n
defining the essential terms and concepts;<\/p>\n<\/li>\n
specifying the types of events;<\/p>\n<\/li>\n
classifying the occurrences of events;<\/p>\n<\/li>\n
describing the usage of modified symbols and methods of graphical representation for ETA, FTA and Markov techniques for applying those modified techniques complementarily to the complex systems;<\/p>\n<\/li>\n
suggesting ways to handle the event frequency\/rate of complex systems;<\/p>\n<\/li>\n
suggesting ways to estimate the event frequency\/rate based on risk monitoring;<\/p>\n<\/li>\n
providing illustrative and practical examples.<\/p>\n<\/li>\n<\/ul>\n
The relationship between the events covered by this document and associated risks are described in Table 1. Risk is defined as the effect of uncertainty on objectives (see 3.1.1). The uncertainty is here assumed to be composed of two elements: the epistemic and aleatory. The epistemic is categorised into the known and unknown, and the effect of the aleatory is classified into the controlled and the uncontrolled, respectively. Therefore, the risk associated with the known event of which impact is controlled is the controlled risk, and the risk associated with the known event of which impact is not controlled is the uncontrolled risk. Favourable meta-risk is of an unknown event of which impact can be casually controlled even if this unknown event appears, and unfavourable meta-risk is of an unknown event of which impact cannot be controlled.<\/p>\n
For example, the risks resulting from random hardware failures of electrotechnical items will be categorised into the controlled or uncontrolled risks, while the risks owing to software bugs could be classified into the favourable or unfavourable meta-risks. This document covers the controlled and uncontrolled risks resulting from the events that can be assumed to occur randomly and independently of time (see Clause 6, 9.1, 9.2, 9.5 and Clause B.3).<\/p>\n
Table 1 \u2013 Events and associated risks<\/b><\/p>\n Probabilistic risk analysis of technological systems. Estimation of final event rate at a given initial state<\/b><\/p>\nPDF Catalog<\/h4>\n
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\n PDF Pages<\/th>\n PDF Title<\/th>\n<\/tr>\n \n 4<\/td>\n CONTENTS <\/td>\n<\/tr>\n \n 7<\/td>\n FOREWORD <\/td>\n<\/tr>\n \n 9<\/td>\n INTRODUCTION <\/td>\n<\/tr>\n \n 11<\/td>\n 1 Scope
Tables
Table 1 \u2013 Events and associated risks <\/td>\n<\/tr>\n\n 12<\/td>\n 2 Normative references
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions <\/td>\n<\/tr>\n\n 19<\/td>\n 3.2 Abbreviated terms
4 Difference between frequency and rate of final event <\/td>\n<\/tr>\n\n 20<\/td>\n Figures
Figure\u00a01 \u2013 Antecedent state, final event, final state and renewal event <\/td>\n<\/tr>\n\n 21<\/td>\n 5 Final event frequency and final event rate at a given initial state
5.1 General
5.2 Classification of final events
Figure 2 \u2013 Time to final event (TTFE) and time to renewal event (TTRE) <\/td>\n<\/tr>\n\n 22<\/td>\n 5.3 Final event frequency in a steady state <\/td>\n<\/tr>\n \n 23<\/td>\n Figure\u00a03 \u2013 State transition models with various final states <\/td>\n<\/tr>\n \n 24<\/td>\n 5.4 Final event rate at a given initial state and at a recognised state
5.5 Relationship between final event rate and frequency at a given initial state <\/td>\n<\/tr>\n\n 25<\/td>\n 6 Procedure for probabilistic risk analysis and flow to reach risk profile <\/td>\n<\/tr>\n \n 26<\/td>\n 7 Techniques for quantitative analysis of the occurrence of a final event
7.1 Graphical symbols for three types of final events
7.1.1 General
7.1.2 Repeatable final eventTable 3
Figure 4 \u2013 Procedure for analysis of repeatable\/unrepeatable final events <\/td>\n<\/tr>\n\n 27<\/td>\n Table 2 \u2013 Symbols newly introduced for event tree and fault tree analyses <\/td>\n<\/tr>\n \n 28<\/td>\n Table 3 \u2013 Symbols and graphical representation for a repeatable (final) event <\/td>\n<\/tr>\n \n 29<\/td>\n Table 4 \u2013 Symbols and graphical representation for a renewable final state <\/td>\n<\/tr>\n \n 31<\/td>\n Table 5 \u2013 Symbols and graphical representation for an unrenewable final state <\/td>\n<\/tr>\n \n 32<\/td>\n 7.1.3 Unrepeatable final event resulting in a renewable final state
7.1.4 Unrepeatable final event resulting in an unrenewable final state <\/td>\n<\/tr>\n\n 33<\/td>\n 7.2 Analytical example of an unrepeatable final event
7.2.1 General
Figure 5 \u2013 FT for an unrepeatable final event resulting in an unrenewable final state <\/td>\n<\/tr>\n\n 34<\/td>\n 7.2.2 Average final event frequency
Figure 6 \u2013 State transition model resulting in an unrenewable final state <\/td>\n<\/tr>\n\n 36<\/td>\n 7.2.3 Final event rate at a given initial state <\/td>\n<\/tr>\n \n 37<\/td>\n Figure 7 \u2013 FT for an unrepeatable final event resulting in a renewable final state
Figure\u00a08 \u2013 State transitions resulting in a renewable final state <\/td>\n<\/tr>\n\n 40<\/td>\n Figure 9 \u2013 FT for unintended inflation of an airbag due to failure of control <\/td>\n<\/tr>\n \n 41<\/td>\n Figure 10 \u2013 State transition model of unintended inflation of an airbag <\/td>\n<\/tr>\n \n 42<\/td>\n 8 Final event rate at a recognised state and recognised group state
8.1 General
8.2 Example of recognised (group) states <\/td>\n<\/tr>\n\n 43<\/td>\n Table\u00a06 \u2013 Symbols and graphical representation for the FER at recognised state 3 <\/td>\n<\/tr>\n \n 44<\/td>\n Table 7 \u2013 Symbols and graphical representation for FER at recognised group state G <\/td>\n<\/tr>\n \n 45<\/td>\n 9 Analysis of multiple protection layers
9.1 General <\/td>\n<\/tr>\n\n 46<\/td>\n Figure\u00a011 \u2013 Event tree of a demand source, int. PL and FPL for a risk <\/td>\n<\/tr>\n \n 47<\/td>\n 9.2 Frequency and rate for repeatable events
9.2.1 General
9.2.2 Independent of event sequence <\/td>\n<\/tr>\n\n 48<\/td>\n Figure 12 \u2013 Failure of int. PL independent of event sequence <\/td>\n<\/tr>\n \n 49<\/td>\n 9.2.3 Depending on event sequence <\/td>\n<\/tr>\n \n 51<\/td>\n Figure\u00a013 \u2013 FT for failure of int. PL through sequential failure logic <\/td>\n<\/tr>\n \n 53<\/td>\n 9.3 Final protection layer arranged in a 1-out-of-1 architecture system
9.3.1 General
9.3.2 Final event rate at initial state (0, 0) for unrepeatable final event <\/td>\n<\/tr>\n\n 55<\/td>\n 9.3.3 Final event rate at recognised state (x, y)
Figure 14 \u2013 FT for an unrepeatable final event at initial state (0,0)
Figure\u00a015 \u2013 State transition model for an unrepeatable final event at initial state (0,0) <\/td>\n<\/tr>\n\n 56<\/td>\n 9.3.4 Final event rate at a recognised group state
Figure\u00a016 \u2013 FT for an unrepeatable final event for recognised state (0,1)
Figure 17 \u2013 State transition model for recognised state (0,1) <\/td>\n<\/tr>\n\n 57<\/td>\n Figure 18 \u2013 FT for an unrepeatable final event for recognised group state G1 <\/td>\n<\/tr>\n \n 58<\/td>\n 9.4 Final protection layer arranged in a 1-out-of-2 architecture system
9.4.1 General
Figure\u00a019 \u2013 State transition model for recognised group state G1 <\/td>\n<\/tr>\n\n 59<\/td>\n 9.4.2 Independent failure parts of the 1-out-of-2 architecture system
Figure 20 \u2013 RBD of FPL arranged in a 1-out-of-2 architecture system
Figure 21 \u2013 RBD of the independent parts of Ch 1 and Ch 2 <\/td>\n<\/tr>\n\n 60<\/td>\n 9.4.3 Fault tree for independent undetected and detected failures
9.4.4 Final event rate at a given initial state owing to independent failures
Figure 22 \u2013 RBD equivalent to that in Figure 21
Figure\u00a023 \u2013 FT for UD failure of Ch 1, D failure of Ch 2 and demand <\/td>\n<\/tr>\n\n 61<\/td>\n 9.4.5 Recognised states at each part
Figure 24 \u2013 State transitions due to UD failure of Ch 1, D failure of Ch 2 and demand <\/td>\n<\/tr>\n\n 62<\/td>\n 9.4.6 Recognised (group) states and final states for the overall system <\/td>\n<\/tr>\n \n 63<\/td>\n 9.5 Common cause failures between protection layers and complexity of a system
9.6 Summary and remarks <\/td>\n<\/tr>\n\n 64<\/td>\n Annex A (informative) Risk owing to fault recognised only by demand
A.1 Demand, detection and failure logic
Figure A.1 \u2013 Reliability bock diagram with independent and common cause failures <\/td>\n<\/tr>\n\n 65<\/td>\n Figure A.2 \u2013 Fault tree of unrepeatable final event due to DU failures <\/td>\n<\/tr>\n \n 66<\/td>\n A.2 Final event rate at a given initial state
Figure A.3 \u2013 State transition model for unrepeatable final event caused by DU failures <\/td>\n<\/tr>\n\n 67<\/td>\n A.3 Comparison between new and conventional analyses <\/td>\n<\/tr>\n \n 69<\/td>\n A.4 Further development
Figure A.4 \u2013 Comparison between analyses of r(\u03bbM) and \u03d6 <\/td>\n<\/tr>\n\n 70<\/td>\n A.5 Summary and remarks <\/td>\n<\/tr>\n \n 71<\/td>\n Annex B (informative) Application to functional safety
B.1 Risk-based target failure measures in functional safety <\/td>\n<\/tr>\n\n 72<\/td>\n B.2 Safe\/dangerous system states and failures <\/td>\n<\/tr>\n \n 74<\/td>\n B.3 Complexity of safety-related systems
Table B.1 \u2013 Relationship between failure modes, hazards, and safe\/dangerous failures <\/td>\n<\/tr>\n\n 75<\/td>\n B.4 Comparison between conventional and new analyses <\/td>\n<\/tr>\n \n 76<\/td>\n B.5 Splitting up mode of operation
Figure B.1 \u2013 Comparison between conventional and new analyses <\/td>\n<\/tr>\n\n 77<\/td>\n B.6 Tolerable hazardous\/harmful event rate and residual risk
B.7 Procedure for determining the safety integrity level (SIL) of an item <\/td>\n<\/tr>\n\n 78<\/td>\n B.8 Summary and remarks
Table\u00a0B.2 \u2013 Safety integrity levels (SILs) in IEC\u00a061508 (all parts) <\/td>\n<\/tr>\n\n 79<\/td>\n Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" \n\n
\n Published By<\/td>\n Publication Date<\/td>\n Number of Pages<\/td>\n<\/tr>\n \n BSI<\/b><\/a><\/td>\n 2016<\/td>\n 84<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"featured_media":344239,"template":"","meta":{"rank_math_lock_modified_date":false,"ep_exclude_from_search":false},"product_cat":[94,2641],"product_tag":[],"class_list":{"0":"post-344235","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"product_cat-03-120-01","7":"product_cat-bsi","9":"first","10":"instock","11":"sold-individually","12":"shipping-taxable","13":"purchasable","14":"product-type-simple"},"_links":{"self":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product\/344235","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/types\/product"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media\/344239"}],"wp:attachment":[{"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/media?parent=344235"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_cat?post=344235"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/pdfstandards.shop\/wp-json\/wp\/v2\/product_tag?post=344235"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}