Dependability management - Part 3-4: Application guide - Specification of dependability requirements

IEC 60300-3-4:2022 gives guidance on specifying dependability requirements and collating these requirements in a specification, together with a list of the means of assuring the achievement of the dependability requirements.
The guidance provided includes:
• specifying quantitative and qualitative reliability, maintainability, supportability and availability requirements;
• advising acquirers on how to ensure that the requirements can be fulfilled by suppliers;
• advising suppliers to help them meet the acquirer's requirements.
Other obligations, such as legislation and governmental regulations, can also place requirements on items, in addition to any requirements derived in accordance with this document.

Gestion de la sûreté de fonctionnement - Partie 3-4: Guide d'application - Spécification d'exigences de sûreté de fonctionnement

L'IEC 60300-3-4:2022 fournit des recommandations relatives à la spécification des exigences de sûreté de fonctionnement et au rassemblement de ces exigences dans une spécification, ainsi qu'une liste des moyens permettant d’assurer la réalisation des exigences de sûreté de fonctionnement.
Les recommandations fournies comprennent:
• la spécification d’exigences quantitatives et qualitatives de fiabilité, de maintenabilité, de supportabilité et de disponibilité;
• des conseils aux acquéreurs portant sur la façon d’assurer que les exigences peuvent être satisfaites par les fournisseurs;
• des conseils aux fournisseurs afin de les aider à satisfaire aux exigences des acquéreurs.
D’autres obligations telles que des règlements législatifs et gouvernementaux peuvent aussi imposer des exigences relatives aux entités, en plus de toutes les exigences déduites conformément au présent document.

General Information

Status
Published
Publication Date
10-Mar-2022
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
11-Mar-2022
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IEC 60300-3-4
Edition 3.0 2022-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Dependability management –
Part 3-4: Application guide – Specification of dependability requirements
Gestion de la sûreté de fonctionnement –
Partie 3-4: Guide d'application – Spécification d'exigences de sûreté de
fonctionnement
IEC 60300-3-4:2022-03(en-fr)
---------------------- Page: 1 ----------------------
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IEC 60300-3-4
Edition 3.0 2022-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Dependability management –
Part 3-4: Application guide – Specification of dependability requirements
Gestion de la sûreté de fonctionnement –
Partie 3-4: Guide d'application – Spécification d'exigences de sûreté de
fonctionnement
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 03.100.40; 03.120.01 ISBN 978-2-8322-1059-0

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 60300-3-4:2022 © IEC 2022
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 8

2 Normative references ...................................................................................................... 8

3 Terms and definitions ...................................................................................................... 8

4 Specifying dependability ................................................................................................ 10

4.1 Description of dependability specification .............................................................. 10

4.2 Principles .............................................................................................................. 13

4.3 Benefits ................................................................................................................ 15

5 Derivation of dependability requirements ....................................................................... 15

5.1 General ................................................................................................................. 15

5.2 Define stakeholder needs and expectations .......................................................... 17

5.3 Develop supporting documentation ....................................................................... 18

5.4 Derive dependability requirements ........................................................................ 19

5.5 Justify the measures used for the dependability requirements ............................... 33

5.6 Complete dependability specification .................................................................... 34

5.7 Review dependability specification ........................................................................ 34

Annex A (informative) Discussion on useful life .................................................................... 35

A.1 General ................................................................................................................. 35

A.2 Factors that determine useful life .......................................................................... 35

A.3 Specification of useful life of non-repairable items (components) .......................... 36

Annex B (informative) Process for prioritizing dependability attributes ................................. 38

Annex C (informative) Development of a dependability specification for a home

security system .............................................................................................................. 40

C.1 Define stakeholder needs and expectations .......................................................... 40

C.2 Develop supporting documentation ....................................................................... 40

C.3 Derive the dependability requirements .................................................................. 45

C.4 Complete dependability specification .................................................................... 46

Annex D (informative) Influencing factors for dependability specification .............................. 48

D.1 Examples of constraints on system dependability .................................................. 48

D.2 Type of system operation ...................................................................................... 48

D.3 Criticality of operation ........................................................................................... 49

D.4 Determining relevant influencing factors for the evaluation of system

functions ............................................................................................................... 52

Bibliography .......................................................................................................................... 54

Figure 1 – High level process for derivation of dependability requirements in the

specification.......................................................................................................................... 16

Figure 2 – What are we trying to achieve? ............................................................................ 18

Figure 3 – What do we need to manage? .............................................................................. 22

Figure 4 – What constraints are there? ................................................................................. 22

Figure 5 – Assurance considerations .................................................................................... 23

Figure 6 – Reliability requirements ........................................................................................ 27

Figure 7 – Maintainability requirements ................................................................................. 28

Figure 8 – Supportability requirements .................................................................................. 31

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IEC 60300-3-4:2022 © IEC 2022 – 3 –

Figure 9 – Availability requirements ...................................................................................... 33

Figure B.1 – Process for prioritizing attributes ....................................................................... 39

Figure C.1 – System configuration for normal mode of operation .......................................... 44

Figure C.2 – System configuration for panic mode of operation ............................................. 44

Figure C.3 – System configuration for security service mode of operation ............................. 45

Table B.1 – Questions for prioritizing dependability attributes ............................................... 38

Table D.1 – Examples of influencing factors under each influencing condition ...................... 52

Table D.2 – Relationship of system properties with influencing conditions ............................ 53

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– 4 – IEC 60300-3-4:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
DEPENDABILITY MANAGEMENT –
Part 3-4: Application guide –
Specification of dependability requirements
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international

co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and

in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,

Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their

preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with

may participate in this preparatory work. International, governmental and non-governmental organizations liaising

with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for

Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence between

any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.

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6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

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expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent

rights. IEC shall not be held responsible for identifying any or all such patent rights.

IEC 60300-3-4 has been prepared by IEC technical committee 56: Dependability. It is an

International Standard.

This third edition cancels and replaces the second edition published in 2007. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) consistency with the other of the six core IEC dependability standards;
b) a process for defining requirements has been included;

c) the definitions and language used have been made consistent with other system related

standards.
---------------------- Page: 6 ----------------------
IEC 60300-3-4:2022 © IEC 2022 – 5 –
The text of this International Standard is based on the following documents:
Draft Report on voting
56/1932/FDIS 56/1939/RVD

Full information on the voting for its approval can be found in the report on voting indicated in

the above table.
The language used for the development of this International Standard is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in

accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available

at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are

described in greater detail at www.iec.ch/standardsdev/publications.

A list of all parts in the IEC 60300 series, published under the general title Dependability

management, can be found on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under webstore.iec.ch in the data related to the

specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it

contains colours which are considered to be useful for the correct understanding of its

contents. Users should therefore print this document using a colour printer.
---------------------- Page: 7 ----------------------
– 6 – IEC 60300-3-4:2022 © IEC 2022
INTRODUCTION

Dependability is the ability to perform as and when required. A dependable item is one where

there is justified confidence that it operates as desired and satisfies agreed stakeholder

expectations.

Dependability has many attributes, but is usually characterized in terms of reliability,

maintainability, and supportability, and the derived characteristic of availability. Dependability

also includes the performance characteristics such as durability, testability and restorability as

well as security and integrity, particularly in relation to software-based systems.

Dependability is an important attribute that affects the value items generate. Consequently,

relevant dependability attributes should be defined and specified in addition to functional

performance requirements and physical attributes. Whilst mainly addressing system and

equipment level dependability, many of the techniques described in the various dependability

related IEC standards may also be applied to products or at the component level. The term

"item" is used throughout this document to mean an individual part, component, device,

functional unit, off-the-shelf (OTS) equipment, subsystem, or system. The item may consist of

hardware, software, people or any combination thereof (see IEC 60050-192). In order to refer

to a specific kind of "item", terms like component, OTS, product or large open system are used.

Dependability attributes may be specified for an individual system or product (for example, a

vehicle) and/or a group of similar systems or products (for example, a fleet of similar vehicles).

Dependability attributes may be specified using either quantitative and/or qualitative measures.

In order to assess the values of some of the dependability attributes achieved, statistical

methods may be necessary.

The levels of reliability, maintainability, supportability and availability achieved by an item

depend on the conditions under which it is realized, utilized, maintained and supported and also

on the life profile of the system. The requirements in the dependability specification, should

also define the following:
• conditions under which the item is stored, transported, realized and utilized;
• life profile and expected useful life;
• maintenance policies;
• available support.

Dependability attributes may be specified, along with other performance characteristics, in

various ways depending on the situation. In a basic project context where an acquirer obtains

an item from a supplier, three main types are:
1) specifications written by the supplier;
2) specifications written by the acquirer;
3) specifications mutually agreed or written by the supplier and the acquirer.

The guidance in this document is applicable to all three types of specifications and may be

adapted to other situations as needed.

This document provides guidance for writing dependability requirements in specifications,

together with a means of assuring the achievement of those requirements.
---------------------- Page: 8 ----------------------
IEC 60300-3-4:2022 © IEC 2022 – 7 –

This document is one of the six "top level" interrelated dependability standards that provide

managers and technical personnel with guidance on how to effectively plan and implement

dependability activities. As such, this document should be used in conjunction with:

• IEC 60300-1 [1] , which highlights the importance and benefits of managing dependability.

It gives guidance on dependability activities and how to integrate them into an existing

management system and life cycle processes;

• IEC 60300-3-1 [2], IEC 60300-3-10 [3], IEC 60300-3-14 [4] which provide guidance on how

to identify and apply appropriate analysis and assurance techniques for reliability,

maintainability (and maintenance) and supportability (and support) respectively. A standard

to cover availability is planned.
____________
Numbers in square brackets refer to the Bibliography.
---------------------- Page: 9 ----------------------
– 8 – IEC 60300-3-4:2022 © IEC 2022
DEPENDABILITY MANAGEMENT –
Part 3-4: Application guide –
Specification of dependability requirements
1 Scope

This part of IEC 60300 gives guidance on specifying dependability requirements and collating

these requirements in a specification, together with a list of the means of assuring the

achievement of the dependability requirements.
The guidance provided includes:

• specifying quantitative and qualitative reliability, maintainability, supportability and

availability requirements;

• advising acquirers on how to ensure that the requirements can be fulfilled by suppliers;

• advising suppliers to help them meet the acquirer's requirements.

Other obligations, such as legislation and governmental regulations, can also place

requirements on items, in addition to any requirements derived in accordance with this

document.

Whilst mainly addressing system and equipment level dependability, many of the techniques

described in the various dependability related IEC standards can also be applied to products or

at the component level. The term "item" is used throughout this document.

This guidance is given in a basic project context where an acquirer obtains an item from a

supplier. It can be modified and adapted to other situations as needed.

NOTE 1 This document does not directly consider safety and environment specifications although much of the

guidance in this document could also be applied to them.

NOTE 2 This document does not cover items with special multi-stakeholder long-term arrangements (e.g. services

provided through Public-Private Partnership procurements) and how dependability is specified in such arrangements.

NOTE 3 The guidance in this document can be applied to some aspects of the specification of requirements relating

to software but specific guidance can be found in IEC 62628 [5] and the different parts of the IEC 61508 series [6].

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies.

For undated references, the latest edition of the referenced document (including any

amendments) applies.

IEC 60050-192, International Electrotechnical Vocabulary (IEV) – Part 192: Dependability

(available at http://www.electropedia.org)
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 60050-192 and the

following apply.
---------------------- Page: 10 ----------------------
IEC 60300-3-4:2022 © IEC 2022 – 9 –

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp

NOTE Definitions of "dependability", "availability", "reliability", "maintainability", "supportability”, "failure", "fault",

“time to failure", "operating time between failures", "verification" and "validation" are given in IEC 60050-192.

3.1
goal

statement which translates or expresses desires or aspirations and for which evidence of

fulfilment either need not or cannot be provided
3.2
item
subject being considered

Note 1 to entry: The item may be an individual part, component, device, functional unit, equipment, subsystem, or

system.

Note 2 to entry: The item may consist of hardware, software, people or any combination thereof.

Note 3 to entry: The item is often comprised of elements that may each be individually considered.

[SOURCE: IEC 60050-192:2015, 192-01-01, modified – Note 3 modified by omission of internal

references and Notes 4 and 5 deleted.]
3.3
off-the-shelf
OTS

non-developmental item of supply that is both commercial and sold in substantial quantities in

the commercial marketplace

Note 1 to entry: Sometimes referred to as COTS (commercial off-the-shelf) or MOTS (modified off-the-shelf).

3.4
requirement

statement which translates or expresses a need and its associated constraints and conditions

Note 1 to entry: Requirements exist at different levels in the system structure.

Note 2 to entry: A requirement is an expression of one or more particular needs in a very specific, precise and

unambiguous manner.

Note 3 to entry: A requirement always relates to a system, product or service, or other item of interest.

Note 4 to entry: A requirement is a statement where evidence or assurance of compliance can be provided.

[SOURCE: ISO/IEC/IEEE 29148:2018, 3.1.19 [7], modified – Note 4 added.]
3.5
specification

information item that identifies the dependability requirements and goals of

a system, product or service together with any supporting information

Note 1 to entry: Supporting information can include details of use, operating and environmental conditions, failure

criteria and the methods intended to be applied for assurance of compliance with the requirements, including

accept/reject criteria.

Note 2 to entry: ISO/IEC/IEEE 15289 [8] defines specification as an information item that identifies in a complete,

precise and verifiable manner the requirements, design, behaviour or other expected characteristics of the system,

service or process. The specification of dependability has a greater scope than that used in ISO/IEC/IEEE 15289.

---------------------- Page: 11 ----------------------
– 10 – IEC 60300-3-4:2022 © IEC 2022
3.6
useful life

time interval from first use until user requirements are no longer met due to

performance, obsolescence and/or economic factors

Note 1 to entry: The applicable time interval is dependent on the nature and application of the item and can be

elapsed time, operating hours, number of cycles, etc.

Note 2 to entry: Performance factors to be considered for useful life include a decrease in item performance below

acceptable limits which cannot be rectified, a change in performance or service requirements, increase in failure

probability or decrease in availability.

Note 3 to entry: Economic factors to be considered for useful life include excessive maintenance costs, increases

in operating costs and emergence of more cost-effective solutions.

Note 4 to entry: In some cases, the useful life of an item is more than that required by an organization, in which

case it has residual value and could be repurposed.

Note 5 to entry: In this context, "first use" excludes testing activities prior to hand-over of the item to the end-user.

[SOURCE: IEC 60500-192:2015, 192-02-27, modified – "economics of operation and

maintenance, or obsolescence" replaced by "performance, obsolescence and/or economic

factors".]
4 Specifying dependability
4.1 Description of dependability specification
4.1.1 What is dependability?

Dependability is the ability to perform as and when required. A dependable item is one where

there is justified confidence that it operates as desired and satisfy agreed stakeholder

expectations.

Dependability has a strong impact on the user's perception of the value of an item developed

or provided by an organization and poor dependability affects an organization's profitability and

reputation.

Dependability is specified and verified using a set of measurable or demonstrable attributes,

which are quantified, where practicable. Dependability is usually characterized in terms of

reliability, maintainability, and supportability, and the derived characteristic of availability.

• Reliability relates to the ability to provide a required function for a given interval (time,

operating cycles, distance, etc.).

• Maintainability relates to the ease and speed with which an item can be retained in, or

restored to, a state to perform as
...

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