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AS/NZS IEC 61703:2020

Current
Current

The latest, up-to-date edition.

Mathematical expressions for reliability, availability, maintainability and maintenance support terms
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Language(s)

English

Published date

01-05-2020

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This Standard adopts IEC 61703:2016 which provides mathematical expressions for selected reliability, availability, maintainability and maintenance support measures defined in IEC 60050-192:2015. In addition, it introduces some terms not covered in IEC 60050-192:2015. They are related to aspects of the system of item classes (see hereafter).

his International Standard provides mathematical expressions for selected reliability, availability, maintainability and maintenance support measures defined in IEC 60050192: 2015. In addition, it introduces some terms not covered in IEC 60050-192:2015. They are related to aspects of the system of item classes (see hereafter).
According to IEC 60050-192:2015, dependability [192-01-22] is the ability of an item to perform as and when required and an item [192-01-01] can be an individual part, component, device, functional unit, equipment, subsystem, or system.
To account for mathematical constraints, this standard splits the items between the individual items considered as a whole (e.g. individual components) and the systems made of several individual items. It provides general considerations for the mathematical expressions for systems as well as individual items but the individual items which are easier to model are analysed in more detail with regards to their repair aspects.
The following item classes are considered separately:
- Systems;
- Individual items:
– non-repairable [192-01-12];
– repairable [192-01-11]:
i) with zero (or negligible) time to restoration;
ii) with non-zero time to restoration.
In order to explain the dependability concepts which can be difficult to understand, keep the standard self-contained and the mathematical formulae as simple as possible, the following basic mathematical models are used in this standard to quantify dependability measures:
- Systems:
– state-transition models;
– Markovian models.
- Individual items:
– random variable (time to failure) for non-repairable items;
– simple (ordinary) renewal process for repairable items with zero time to restoration;
– simple (ordinary) alternating renewal process for repairable items with non-zero time to restoration.
The application of each dependability measure is illustrated by means of simple examples.
This standard is mainly applicable to hardware dependability, but many terms and their definitions may be applied to items containing software.

Committee
QR-005
DocumentType
Standard
ISBN
978 1 76072 831 1
Pages
90
PublisherName
Standards Australia
Status
Current
Supersedes

Standards Relationship
IEC 61703:2016 Identical

First published as AS/NZS IEC 61703:2020.

ISO 3534-1:2006 Statistics — Vocabulary and symbols — Part 1: General statistical terms and terms used in probability
IEC 61508-4:2010 Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 4: Definitions and abbreviations (see Functional Safety and IEC 61508)
IEC 61508-5:2010 Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 5: Examples of methods for the determination of safety integrity levels (see Functional Safety and IEC 61508)
IEC 61508-6:2010 Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 6: Guidelines on the application of IEC 61508-2 and IEC 61508-3 (see Functional Safety and IEC 61508)
IEC 61025:2006 Fault tree analysis (FTA)
IEC 60605-6:2007 Equipment reliability testing - Part 6: Tests for the validity and estimation of the constant failure rate and constant failure intensity
IEC 60605-4:2001 Equipment reliability testing - Part 4: Statistical procedures for exponential distribution - Point estimates, confidence intervals, prediction intervals and tolerance intervals
IEC 61511-2:2016 Functional safety - Safety instrumented systems for the process industry sector - Part 2: Guidelines for the application of IEC 61511-1:2016
IEC 61078:2016 Reliability block diagrams
IEC 61508-1:2010 Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 1: General requirements (see Functional Safety and IEC 61508)
IEC 60605-2:1994 Equipment reliability testing - Part 2: Design of test cycles
IEC 61165:2006 Application of Markov techniques
IEC 61508-7:2010 Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 7: Overview of techniques and measures (see Functional Safety and IEC 61508)
IEC 61511-3:2016 Functional safety - Safety instrumented systems for the process industry sector - Part 3: Guidance for the determination of the required safety integrity levels
IEC 61511-1:2016+AMD1:2017 CSV Functional safety - Safety instrumented systems for the process industry sector - Part 1: Framework, definitions, system, hardware and application programming requirements
IEC 61508-2:2010 Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 2: Requirements for electrical/electronic/programmable electronic safety-related systems (see Functional Safety and IEC 61508)
IEC 61508-3:2010 Functional safety of electrical/electronic/programmable electronic safety-related systems - Part 3: Software requirements (see Functional Safety and IEC 61508)
IEC 60050-192:2015 International Electrotechnical Vocabulary (IEV) - Part 192: Dependability

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