TC 56 - Dependability

IEC 60300-3-14:2024 introduces the dependability attribute of supportability (and support) and the relationship with related dependability attributes of reliability, maintainability and availability.
This document can be used at any time during an item’s life to guide the planning and implementing of supportability and support activities focused on achieving an intended balance of performance, cost and risk. All activities can be tailored to the nature of the item and its conditions of use.
Guidance is offered on how supportability and support activities can be applied at any life cycle stage for newly designed items, existing items available for commercial procurement, or for items during their operational life.
This document considers the life cycle implications by formally managing risks associated with the management and delivery of activities to create, operate, maintain and refurbish an item to achieve its stated purpose.
This document describes the:
- nature of supportability and support;
- role of supportability and support in achieving item value over its life;
- trade-offs associated with supportability and support to achieve desired balance of cost, performance and risk during the life of an item;
- importance of aligning the structure of an organization with its objectives, with the ultimate aim of improving efficiency and effectiveness in order to deliver the required supportability and support.
This second edition cancels and replaces the first edition published in 2004. 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 core dependability standards prepared by IEC TC 56;
b) expansion of supportability and support principles and activities in dependability.

IEC 60300-1:2024 provides guidance on:
- the meaning and significance of dependability from a business, technical and financial perspective;
- achieving dependability through suitable adaptation of organizational management systems such as those described in ISO 9001 (quality management) and ISO 55001 (asset management);
- the activities that are integrated into management systems and life cycle processes in order to achieve dependable systems, products and services;
- planning and implementing dependability activities throughout the life cycle to achieve and assure required outcomes, taking into account factors such as costs, safety, the environment, customer goodwill, brand and reputation.
This document is applicable to any type of system, both new and existing, to mass produced industrial or consumer products, to components and to services. This document addresses all elements of systems, products and services including hardware, software, data, processes, procedures, facilities, materials, and personnel required for operations and support.

IEC 62506:2023 provides guidance on the application of various accelerated test techniques for measurement or improvement of item reliability. Identification of potential failure modes that can be experienced in the use of an item and their mitigation is instrumental to ensure dependability of an item. The object of the methods is to either identify potential design weakness or provide information on item reliability, or to achieve necessary reliability and availability improvement, all within a compressed or accelerated period of time. This document addresses accelerated testing of non-repairable and repairable systems. It can be used for probability ratio sequential tests, fixed duration tests and reliability improvement/growth tests, where the measure of reliability can differ from the standard probability of failure occurrence. This document also extends to present accelerated testing or production screening methods that would identify weakness introduced into the item by manufacturing error, which can compromise item reliability. Services and people are however not covered by this document.

IEC 61124:2023 gives a number of optimized test plans, the corresponding border lines and characteristics. In addition, the algorithms for designing test plans using a spreadsheet program are also given, together with guidance on how to choose test plans.
This document specifies procedures to test whether an observed value of
failure rate,
failure intensity,
mean operating time to failure (MTTF),
mean operating time between failures (MTBF),  conforms to a given requirement.
It is assumed, except where otherwise stated, that during the accumulated test time, the times to failure or the operating times between failures are independent and identically exponentially distributed. This assumption implies that the failure rate or failure intensity is assumed to be constant.

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.

IEC 62960:2020 provides guidance on a review methodology for dependability from a technical perspective that is applicable at all stages of a system life cycle. Its application can improve the dependability of a system throughout its life cycle by triggering appropriate actions at appropriate times to address potential dependability problems.
It provides guidance for developers, manufacturers, users and third-party independent reviewers such as consulting organizations.
This document describes a dependability review methodology focusing on:
- coherence of review activities across life cycle stages and their impact on dependability;
- stakeholder identification and how this affects dependability review activities;
- the relationships between different types of reviews;
- procedures for effective dependability reviews;
- examples of dependability review activities.

IEC 61163-2:2020 provides guidance on RSS techniques and procedures for electrical, electronic, and mechanical components. This document is procedural in nature and is not, and cannot be, exhaustive with respect to component technologies due to the rapid rate of developments in the component industry. This document is:
a) intended for component manufacturers as a guideline;
b) intended for component users as a guideline to negotiate with component manufacturers on RSS requirements;
c) intended to allow the planning of an RSS process in house to meet reliability requirements or to allow the re-qualification of components for specific, upgraded, environments;
d) intended as a guideline to sub-contractors who provide RSS as a service.
This document is not intended to provide test plans for specific components or for delivery of certificates of conformance for batches of components. The use of bi-modal Weibull analysis to select and optimize an RSS process without having to estimate the reliability and life time of all items is described. This second edition cancels and replaces the first edition published in 1998. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) this version of the document is a complete rewrite and restructure from the previous version.

IEC 61123:2019 is intended to define a procedure to verify if a reliability of an item/system complies with the stated requirements. The requirement is assumed to be specified as the percentage of success (success ratio) or the percentage of failures (failure ratio). This document can be used where a number of items are tested (number of trials performed) and classified as passed or failed. It can also be used where one or a number of items are tested repeatedly. The procedures are based on the assumption that the probability of success or failure is the same from trial to trial (statistically independent events). Plans for fixed trial/failure terminated tests as well as truncated sequential probability ratio tests (SPRTs) are included. This document contains extensive tables with ready-to-use SPRT plans and their characteristics for equal and non-equal risks for supplier and customer. In the case of the reliability compliance tests for constant failure rate/intensity, IEC 61124 applies. This second edition cancels and replaces the first edition published in 1991. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
The sequential probability ratio test (SPRT) [1, 2][1] has been significantly developed in recent years [3, 4, 5]. This edition contains shorter and accurate tests, a wide range of test plans, and significant additional characteristic data, as follows:
the tests are significantly truncated (the maximum trial numbers are low) without substantially increasing the expected number of trials to decision (ENT);
the true producer’s and consumer’s risks (α', β') are given and very close to the nominal (α, β);
the range of the test parameters is wide (failure ratio, risks and discrimination ratio);
the test plans include various risk ratios (not restricted to equal risks only);
the values of ENT are accurate and given in the relevant region (for practical use);
guidelines for extension of the test sets (interpolation and extrapolation) are included.
In Annex C, the use of the cumulative binomial distribution function of Excel that simplifies the procedure of designing has been added (Clause C.3).
Keywords: verify if a reliability of an item/system complies with the stated requirements

IEC 31010:2019 is published as a double logo standard with ISO and provides guidance on the selection and application of techniques for assessing risk in a wide range of situations. The techniques are used to assist in making decisions where there is uncertainty, to provide information about particular risks and as part of a process for managing risk. The document provides summaries of a range of techniques, with references to other documents where the techniques are described in more detail. This second edition cancels and replaces the first edition published in 2009. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
• more detail is given on the process of planning, implementing, verifying and validating the use of the techniques;
• the number and range of application of the techniques has been increased;
• the concepts covered in ISO 31000 are no longer repeated in this standard.
Keywords: uncertainty, risk management

IEC 62402:2019 provides requirements and guidance for obsolescence management applicable to any organization that is dependent on another organization to obtain value from the usefulness of the items that it provides. A cost-effective obsolescence management process and the activities used to implement the process are applicable throughout all phases of an item’s life cycle. This document covers the following areas:
• establishing an obsolescence management policy;
• establishing an infrastructure and an organization;
• developing an obsolescence management plan (OMP);
• developing strategies to minimize obsolescence during design;
• determining an obsolescence management approach;
• selecting obsolescence resolution and implementation;
• measuring and improving the performance of the outcomes of the obsolescence management activities.
Guidance on obsolescence management is included as notes, in the informative annexes and references in the Bibliography. This second edition cancels and replaces the first 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) this document has now been written with requirements as a standard, not a guide;
b) this document continues to have guidance in the informative annexes;
c) this document has been written as a general process for all technologies and items.
Keywords: obsolescence management

IEC 60812:2018 explains how failure modes and effects analysis (FMEA), including the failure modes, effects and criticality analysis (FMECA) variant, is planned, performed, documented and maintained. The purpose of failure modes and effects analysis (FMEA) is to establish how items or processes might fail to perform their function so that any required treatments could be identified. An FMEA provides a systematic method for identifying modes of failure together with their effects on the item or process, both locally and globally. It may also include identifying the causes of failure modes. Failure modes can be prioritized to support decisions about treatment. Where the ranking of criticality involves at least the severity of consequences, and often other measures of importance, the analysis is known as failure modes, effects and criticality analysis (FMECA). This document is applicable to hardware, software, processes including human action, and their interfaces, in any combination. An FMEA can be used in a safety analysis, for regulatory and other purposes, but this being a generic standard, does not give specific guidance for safety applications. This third edition cancels and replaces the second edition published in 2006. This edition constitutes a technical revision.This edition includes the following significant technical changes with respect to the previous edition:
a) the normative text is generic and covers all applications;
b) examples of applications for safety, automotive, software and (service) processes have been added as informative annexes;
c) tailoring the FMEA for different applications is described;
d) different reporting formats are described, including a database information system;
e) alternative means of calculating risk priority numbers (RPN) have been added;
f) a criticality matrix based method has been added;
g) the relationship to other dependability analysis methods have been described.
Keywords: failure modes and effects analysis (FMEA), failure modes effects and criticality analysis (FMECA)

IEC 62853:2018 provides guidance in relation to a set of requirements placed upon system life cycles in order for an open system to achieve open systems dependability. This document elaborates on IEC 60300-1 by providing details of the changes needed to accommodate the characteristics of open systems. It defines process views based on ISO/IEC/IEEE 15288:2015, which identifies the set of system life cycle processes. This document is applicable to life cycles of products, systems, processes or services involving hardware, software and human aspects or any integrated combinations of these elements. For open systems, security is especially important since the systems are particularly exposed to attack. This document can be used to improve the dependability of open systems and to provide assurance that the process views specific to open systems achieve their expected outcomes. It helps an organization define the activities and tasks that need to be undertaken to achieve dependability objectives in an open system, including dependability related communication, dependability assessment and evaluation of dependability throughout system life cycles.
Keywords: dependability of open systems

IEC 61709:2017 gives guidance on the use of failure rate data for reliability prediction of electric components used in equipment. The method presented in this document uses the concept of reference conditions which are the typical values of stresses that are observed by components in the majority of applications. Reference conditions are useful since they provide a known standard basis from which failure rates can be modified to account for differences in environment from the environments taken as reference conditions. Each user can use the reference conditions defined in this document or use their own. When failure rates stated at reference conditions are used it allows realistic reliability predictions to be made in the early design phase. The stress models described herein are generic and can be used as a basis for conversion of failure rate data given at these reference conditions to actual operating conditions when needed and this simplifies the prediction approach. Conversion of failure rate data is only possible within the specified functional limits of the components. This document also gives guidance on how a database of component failure data can be constructed to provide failure rates that can be used with the included stress models. Reference conditions for failure rate data are specified, so that data from different sources can be compared on a uniform basis. If failure rate data are given in accordance with this document then additional information on the specified conditions can be dispensed with. This document does not provide base failure rates for components – rather it provides models that allow failure rates obtained by other means to be converted from one operating condition to another operating condition. The prediction methodology described in this document assumes that the parts are being used within its useful life. The methods in this document have a general application but are specifically applied to a selection of component types as defined in Clauses 6 to 20 and I.2. This third edition cancels and replaces the second edition, published in 2011. This edition constitutes a technical revision. This third edition is a merger of IEC 61709:2011 and IEC TR 62380:2004.
This edition includes the following significant technical changes with respect to the previous edition: addition of 4.5 Components choice, 4.6 Reliability growth during the deployment phase of new equipment, 4.7 How to use this document, and of Clause 19 Printed circuit boards (PCB) and Clause 20 Hybrid circuits with respect to IEC TR 62380; addition of failure modes of components in Annex A; modification of Annex B, Thermal model for semiconductors, adopted and revised from IEC TR 62380; modification of Annex D, Considerations on mission profile; modification of Annex E, Useful life models, adopted and revised from IEC TR 62380; revision of Annex F (former B.2.6.4), Physics of failure; addition of Annex G (former Annex C), Considerations for the design of a data base on failure rates, complemented with parts of IEC 60319; addition of Annex H, Potential sources of failure rate data and methods of selection; addition of Annex J, Presentation of component reliability data, based on IEC 60319.
The contents of the corrigendum of October 2019 have been included in this copy.
Keywords: failure rate data, reliability prediction of electric components

IEC 60300-3-3:2017 establishes a general introduction to the concept of life cycle costing and covers all applications. Although costs incurred over the life cycle consist of many contributing elements, this document particularly highlights the costs associated with the dependability of an item. This forms part of an overall dependability management programme as described in IEC 60300-1. Guidance is provided on life cycle costing for use by managers, engineers, finance staff, and contractors; it is also intended to assist those who may be required to specify and commission such activities when undertaken by others. This third edition cancels and replaces the second edition published in 2004. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- addition of a complete analysis process;
- greater reference to international accounting practices;
- increased discussion of financial concepts.

IEC 62550:2017 describes requirements for spare parts provisioning as a part of supportability activities that affect dependability performance so that continuity of operation of products, equipment and systems for their intended application can be sustained. This document is intended for use by a wide range of suppliers, maintenance support organizations and users and can be applied to all items.

IEC 61703:2016 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. This standard is mainly applicable to hardware dependability, but many terms and their definitions may be applied to items containing software. This second edition cancels and replaces the first edition published in 2001. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- standard made as self containing as possible;
- item split between individual items and systems;
- generalization of the dependability concepts for systems made of several components [introduction of the conditional failure intensity (Vesely failure rate);
- introduction of the state-transition and the Markovian models;
- generalization of the availability to production availability];
- introduction of curves to illustrate the various concepts. Keywords: mathematical expressions for dependability

IEC 61078:2016 this International Standard describes:
- the requirements to apply when reliability block diagrams (RBDs) are used in dependability analysis;
- the procedures for modelling the dependability of a system with reliability block diagrams;
- how to use RBDs for qualitative and quantitative analysis;
- the procedures for using the RBD model to calculate availability, failure frequency and reliability measures for different types of systems with constant (or time dependent) probabilities of blocks success/failure, and for non-repaired blocks or repaired blocks;
- some theoretical aspects and limitations in performing calculations for availability, failure frequency and reliability measures;
- the relationships with fault tree analysis (see IEC 61025) and Markov techniques (see IEC 61165). This third edition cancels and replaces the second edition published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- the structure of the document has been entirely reconsidered, the title modified and the content extended and improved to provide more information about availability, reliability and failure frequency calculations;
- Clause 3 has been extended and clauses have been introduced to describe the electrical analogy, the "non-coherent" RBDs and the "dynamic" RBDs;
- Annex B about Boolean algebra methods has been extended;
- Annex C (Calculations of time dependent probabilities), Annex D (Importance factors), Annex E (RBD driven Petri net models) and Annex F (Numerical examples and curves) have been introduced. Keywords: reliability block diagram (RBD)

IEC TR 63039:2016(E) 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. This document deals with the following topics from the perspective of risk analysis:
- defining the essential terms and concepts;
- specifying the types of events;
- classifying the occurrences of events;
- 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;
- suggesting ways to handle the event frequency/rate of complex systems;
- suggesting ways to estimate the event frequency/rate based on risk monitoring;
- providing illustrative and practical examples. Please refer to the Introduction and Scope of the document for addition information regarding the events covered by and associated risks. This document defines the basic properties of events from the perspective of probabilistic risk analysis and use of dependability-related techniques for the analysis of occurrence of the final event that results in a final state in which the final consequences of a risk may appear. Keywords: probabilistic risk analysis, effects of uncertainty, events and associated risks

IEC TS 62775:2016(E) which is a Technical Specification, shows how the IEC dependability suite of standards, systems engineering and the IFRS and IAS standards can support the requirements of asset management, as described by the ISO 5500x suite of standards. This Technical Specification therefore provides:
- a brief introduction to asset management and the requirements for an AMS,
- a description of the benefits from the use of an established and common set of AMS processes and procedures, tools and techniques to manage assets, and
- a description of the relationships between the AMS and the tools and techniques, processes and procedures of:
- ISO/IEC/IEEE 15288:2015, Systems and software engineering - System lifecycle processes,
- IEC dependability standards in particular IEC 60300-3-15, and
- relevant IFRS and supporting IAS standards.
This Technical Specification is intended for:
- asset managers who wish to identify and implement technical and financial processes within an AMS, using dependability techniques and IFRS and IAS standards respectively, and
- systems and dependability engineers who need to apply their technical processes and techniques within an AMS. Keywords: asset management, decision-making processes, ISO 5500x

IEC 61882:2016 provides a guide for HAZOP studies of systems using guide words. It gives guidance on application of the technique and on the HAZOP study procedure, including definition, preparation, examination sessions and resulting documentation and follow-up. Documentation examples, as well as a broad set of examples encompassing various applications, illustrating HAZOP studies are also provided. This second edition cancels and replaces the first edition published in 2001. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- clarification of terminology as well as alignment with terms and definitions within ISO 31000:2009 and ISO Guide 73:2009;
- addition of an improved case study of a procedural HAZOP. Keywords: HAZOP, risks and operability problems

IEC 62741:2015 gives guidance on the content and application of a dependability case and establishes general principles for the preparation of a dependability case. This standard is written in a basic project context where a customer orders a system that meets dependability requirements from a supplier and then manages the system until its retirement. The methods provided in this standard may be modified and adapted to other situations as needed. The dependability case is normally produced by the customer and supplier but can also be used and updated by other organizations. For example, certification bodies and regulators may examine the submitted case to support their decisions and users of the system may update/expand the case, particularly where they use the system for a different purpose. Keywords: dependability, reliability, availability, maintainability, supportability, usability, testability, durability.

IEC 62740:2015 describes the basic principles of root cause analysis (RCA) and specifies the steps that a process for RCA should include. This standard identifies a number of attributes for RCA techniques which assist with the selection of an appropriate technique. It describes each RCA technique and its relative strengths and weaknesses. RCA is used to analyse the root causes of focus events with both positive and negative outcomes, but it is most commonly used for the analysis of failures and incidents. Causes for such events can be varied in nature, including design processes and techniques, organizational characteristics, human aspects and external events. RCA can be used for investigating the causes of non-conformances in quality (and other) management systems as well as for failure analysis, for example in maintenance or equipment testing. RCA is used to analyse focus events that have occurred, therefore this standard only covers a posteriori analyses. It is recognized that some of the RCA techniques with adaptation can be used proactively in the design and development of items and for causal analysis during risk assessment; however, this standard focuses on the analysis of events which have occurred. The intent of this standard is to describe a process for performing RCA and to explain the techniques for identifying root causes. These techniques are not designed to assign responsibility or liability, which is outside the scope of this standard. Keywords: root cause analysis (RCA), RCA techniques

IEC 60300-1:2014 establishes a framework for dependability management. It provides guidance on dependability management of products, systems, processes or services involving hardware, software and human aspects or any integrated combinations of these elements. It presents guidance on planning and implementation of dependability activities and technical processes throughout the life cycle taking into account other requirements such as those relating to safety and the environment. This standard gives guidelines for management and their technical personnel to assist them to optimize dependability. This third edition cancels and replaces the second edition published in 2003 and constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- an updating of definitions to reflect IEC 60050-191:2014;
- an enhanced description of dependability and its attributes;
- a more generic approach to dependability management;
- revised guidelines for application of dependability management;
- a more generic approach to the life cycle;
- a framework for dependability standards. Keywords: dependability management

IEC 60704-2-1:2014 applies to electrical vacuum cleaners (including their accessories and their component parts) for household use in or under conditions similar to those in households. This part of IEC 60704 applies as it is to electrical vacuum cleaners operating in dry conditions. Some additions and modifications for vacuum cleaners operating in wet conditions are under consideration. How to test robotic vacuum cleaners is under consideration for a future edition. This part of IEC 60704 does not apply to vacuum cleaners for industrial or professional purposes. This third edition cancels and replaces the second edition published in 2000. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) introduction of a measuring method on hard floors;
b) inclusion of values for measurement uncertainty;
c) inclusion of values for standard deviation for declaration and verification;
d) update of the definition of the standard test carpet.
This publication is to be read in conjunction with IEC 60704-1:2010.

IEC 62198:2013 provides principles and generic guidelines on managing risk and uncertainty in projects. In particular it describes a systematic approach to managing risk in projects based on ISO 31000, Risk management - Principles and guidelines. Guidance is provided on the principles for managing risk in projects, the framework and organizational requirements for implementing risk management and the process for conducting effective risk management. This standard is not intended for the purpose of certification. This second edition cancels and replaces the first edition, published in 2001, and constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- major restructure and rewrite of the first version;
- now aligned with ISO 31000, Risk management - Principles and guidelines. Key words: managing risk and uncertainty, ISO 31000

IEC 62506:2013 provides guidance on the application of various accelerated test techniques for measurement or improvement of product reliability. Identification of potential failure modes that could be experienced in the use of a product/item and their mitigation is instrumental to ensure dependability of an item. The object of the methods is to either identify potential design weakness or provide information on item dependability, or to achieve necessary reliability/availability improvement, all within a compressed or accelerated period of time. This standard addresses accelerated testing of non-repairable and repairable systems. It can be used for probability ratio sequential tests, fixed duration tests and reliability improvement/growth tests, where the measure of reliability may differ from the standard probability of failure occurrence. This standard also extends to present accelerated testing or production screening methods that would identify weakness introduced into the product by manufacturing error, which could compromise product dependability. Keywords: test techniques for measurement or improvement of product reliability

IEC 62673:2013 describes a generic methodology for dependability assessment and assurance of communication networks from a network life cycle perspective. It presents the network dependability assessment strategies and methodology for analysis of network topology, evaluation of dependability of service paths, and optimization of network configurations in order to achieve network dependability performance and dependability of service. It also addresses the network dependability assurance strategies and methodology for application of network health check, network outage control and test case management to enhance and sustain dependability performance in network service operation. This standard is applicable to network service providers, network designers and developers, and network maintainers and operators for assurance of network dependability performance and assessment of dependability of service. Keywords: methodology for dependability assessment and assurance of communication networks

IEC 61710:2013 specifies procedures to estimate the parameters of the power law model, to provide confidence intervals for the failure intensity, to provide prediction intervals for the times to future failures, and to test the goodness-of-fit of the power law model to data from repairable items. It is assumed that the time to failure data have been collected from an item, or some identical items operating under the same conditions (e.g. environment and load). This second edition cancels and replaces the first edition, published in 2000, and constitutes a technical revision. The main changes with respect to the previous edition are listed below: the inclusion of an additional Annex C on Bayesian estimation for the power law model. Keywords: power law model, Bayesian estimation, reliability of repairable items

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

IEC 62628:2012 addresses the issues concerning software aspects of dependability and gives guidance on achievement of dependability in software performance influenced by management disciplines, design processes and application environments. It establishes a generic framework on software dependability requirements, provides a software dependability process for system life cycle applications, presents assurance criteria and methodology for software dependability design and implementation and provides practical approaches for performance evaluation and measurement of dependability characteristics in software systems. Keywords: software, performance, dependability

IEC 61124:2012 gives a number of optimized test plans, the corresponding operating characteristic curves and expected test times. In addition the algorithms for designing test plans using a spreadsheet program are also given, together with guidance on how to choose test plans. This standard specifies procedures to test whether an observed value of: failure rate, failure intensity, meantime to failure (MTTF), and mean operating time between failures (MTBF). The main changes with respect to the previous edition are as follows:
- A number of new test plans have been added based on the Russian standard GOST R 27.402 [1], and it is intended to align the new edition of MIL-HDBK-781 [2] with this edition. Algorithms for optimizing test plans using a spreadsheet program are given and a number of optimized test plans are listed. Furthermore, emphasis is laid on the fact that the test should be repeated following design changes;
- Discrepancies in test plans A, B as well as Annexes A and B that originated in IEC 60605-7 [3], now withdrawn, have been corrected so these test plans differ from those given in previous editions of IEC 61124. As requested by the National Committees, mathematical background material and spreadsheet program information has been moved to informative annexes. In addition, the symbol lists have been divided, so that some annexes have separate lists of symbols;
- Guidance on how to choose test plans has been added as well as guidance on how to use spreadsheet programs to create them. Test plans A.1 to A.9 and B.1 to B.13 have been corrected;
- Subcluses 8.1, 8.2, 8.3, Clause 9, Annex C, Clauses G.2, I.2, I.3 and Annex J are unchanged, except for updated terminology and references. The contents of the corrigendum of January 2013 have been included in this copy.

IEC 61709:2011 gives guidance on how failure rate data can be employed for reliability prediction of electric components in equipment. Reference conditions are numerical values of stresses that are typically observed by components in the majority of applications. Reference conditions are useful since they are the basis of the calculation of failure rate under any conditions by the application of stress models that take into account the actual operating conditions. This standard also gives guidance on how a database of component failure data can be constructed to provide failure rates that can be used with the included stress models. This edition includes the following significant technical changes with respect to the previous edition:
- the addition of a number of component types and the updating of models for a large number of component types;
- the addition of annexes on reliability prediction, sources of failure rate data and component classification information.

IEC 60300-3-12:2011 is an application guide for establishing an integrated logistic support (ILS) management system. It is intended to be used by a wide range of suppliers including large and small companies wishing to offer a competitive and quality item which is optimized for the purchaser and supplier for the complete life cycle of the item. It also includes common practices and logistic data analyses that are related to ILS. This edition includes the following significant technical changes with respect to the previous edition:
- provision of a better overview of the whole ILS process;
- updating of the document to align with associated dependability standards that were introduced after the previous edition.

IEC 62502:2010 specifies the consolidated basic principles of Event Tree Analysis (ETA) and provides guidance on modelling the consequences of an initiating event as well as analysing these consequences qualitatively and quantitatively in the context of dependability and risk related measures.

IEC 62508:2010 provides guidance on the human aspects of dependability, and the human-centred design methods and practices that can be used throughout the whole system life cycle to improve dependability performance. This standard describes qualitative approaches. This first edition cancels and replaces IEC/PAS 62508 published in 2007.

IEC 61907:2009 gives guidance on dependability engineering of communication networks. It establishes a generic framework for network dependability performance, provides a process for network dependability implementation, and presents criteria and methodology for network technology designs, performance evaluation, security consideration and quality of service measurement to achieve network dependability performance objectives. This standard is applicable to network equipment developers and suppliers, network integrators and providers of network service functions for planning, evaluation and implementation of network dependability.

IEC 60300-3-15:2009 provides guidance for an engineering system's dependability and describes a process for realization of system dependability through the system life cycle. This standard is applicable to new system development and for enhancement of existing systems involving interactions of system functions consisting of hardware, software and human elements.

IEC 60300-3-11:2009 provides guidelines for the development of failure management policies for equipment and structures using reliability centred maintenance (RCM) analysis techniques. This part serves as an application guide and is an extension of IEC 60300-3-10, IEC 60300-3-12 and IEC 60300-3-14. Maintenance activities recommended in all three standards, which relate to preventive maintenance, may be implemented using this standard. The previous edition was based on ATA1-MGS-3; whereas this edition applies to all industries and defines a revised RCM algorithm and approach to the analysis process.

IEC 60300-3-16:2008 describes a framework for the specification of services related to the maintenance support of products, systems and equipment that are carried out during the operation and maintenance phase. The purpose of this standard is to outline, in a generic manner, the development of agreements for maintenance support services as well as guidelines for the management and monitoring of these agreements by both the company and the service provider.

IEC 61649:2008 provides methods for analysing data from a Weibull distribution using continuous parameters such as time to failure, cycles to failure, mechanical stress, etc. This standard is applicable whenever data on strength parameters, e.g. times to failure, cycles, stress, etc. are available for a random sample of items operating under test conditions or in-service, for the purpose of estimating measures of reliability performance of the population from which these items were drawn. The main changes with respect to the previous edition are as follows: the title has been shortened and simplified to read "Weibull analysis"; and provision of methods for both analytical and graphical solutions have been added.

This International Standard gives guidance for reliability growth during final testing or acceptance testing of unique complex systems. It gives guidance on accelerated test conditions and criteria for stopping these tests.

Gives guidance on specifying required dependability characteristics in product and equipment specifications, together with specifications of procedures and criteria for verification. Includes advice on specifying quantitative and qualitative reliability, maintainability and availability requirements. The main changes from the previous edition are: the concept of systems has been included and the need to specify the dependability of the system and not just the physical equipment has been stressed; the need for verification and validation of the requirement has been included; differentiation has been made between requirements, that can be measured and verified and validated, and goals, which cannot; and the content on availability, maintainability and maintenance support has been updated and expanded to similar level of detail to reliability.

This guide has for purpose to provide guidance for the early consideration of testability aspects in design and development, and to assist in determining effective test procedures as an integral part of operation and maintenance. This second edition constitutes a technical revision. It expands and provides more detail on the techniques and systems broadly outlined in the first edition.

This International Standard gives guidance for establishing a framework for obsolescence management and for planning a cost-effective obsolescence management process that is applicable through all phases of the product life cycle.

Specifies procedures to verify the assumption of a constant failure rate or constant failure intensity as defined in IEC 60050(191). These procedures are applicable whenever it is necessary to verify these assumptions. This may be due to a requirement or for the purpose of assessing the behaviour in time of the failure rate or the failure intensity. The major technical changes with respect to the previous edition concern the inclusion of corrected formulae for tests previously included in a corrigendum, and the addition of new methods for the analysis of multiple items.

Describes fault tree analysis and provides guidance on its application to perform an analysis, identifies appropriate assumptions, events and failure modes, and provides identification rules and symbols.

This part of IEC 60079 explains the potential ignition hazard from equipment using optical radiation intended for use in explosive gas atmospheres. It also covers equipment, which itself is located outside but its emitted optical radiation enters such atmospheres. It describes precautions and requirements to be taken when using optical radiation transmitting equipment in explosive gas atmospheres. The contents of the corrigendum of March 2010 and Interpretation sheet 1 of March 2014 have been included in this copy.

This International Standard describes early reliability assessment methods for items based on field data and test data for components and modules. It is applicable to mission, safety and business critical, high integrity and complex items. It contains information on why early reliability estimates are required and how and where the assessment would be used.