IEC 61124-2023 PDF

Full title and description

Reliability testing - Compliance tests for constant failure rate and constant failure intensity. This International Standard specifies procedures and optimized test plans to determine whether observed failure-rate/ failure-intensity/MTTF/MTBF values conform to a stated requirement, under the assumption of constant failure rate (exponentially distributed times to failure).

Abstract

IEC 61124:2023 provides a set of optimized test plans, their operating characteristics and border lines, plus algorithms for designing those plans using spreadsheet programs and guidance on selecting an appropriate plan. It specifies procedures to test whether an observed failure rate, failure intensity, mean time to failure (MTTF) or mean time between failures (MTBF) meets a given requirement, assuming independent, identically exponentially distributed failure/operating times (constant failure rate). The document describes several test-plan types (including truncated SPRT, fixed time/failure terminated tests, fixed calendar time terminated tests and combined tests) and notes that it does not cover practical test conditions or full test planning/reporting guidance (see related IEC documents for that material).

General information

• Status: Published (International Standard, current edition).
• Publication date: 24 February 2023.
• Publisher: International Electrotechnical Commission (IEC), TC 56 Dependability.
• ICS / categories: 03.120.30 (Application of statistical methods); 19.020 (Test conditions and procedures in general); 21.020 (Characteristics and design of machines, apparatus, equipment).
• Edition / version: Edition 4.0 (2023).
• Number of pages: 182 pages (official IEC publication metadata).

Scope

This standard specifies statistical procedures and optimized test plans to assess whether measured reliability metrics (failure rate, failure intensity, MTTF, MTBF) satisfy specified requirements under the model of a constant failure rate (exponential life distribution). It lists and characterizes several test-plan types, provides algorithms for constructing and optimizing plans (suitable for spreadsheet implementation) and offers guidance for selecting suitable plans. It does not provide practical test-condition specifications or step‑by‑step test execution/reporting instructions (see IEC 60300-3-5 and IEC 60605‑2 for planning/conditions and reporting guidance).

Key topics and requirements

• Optimized test plans and their operating characteristic curves and border lines for compliance testing of constant failure rate assumptions.
• Test-plan types: truncated sequential probability ratio test (SPRT), fixed time/failure terminated tests, fixed calendar time terminated tests (without replacement), and combined tests.
• Procedures to evaluate conformity of observed failure rate, failure intensity, MTTF and MTBF to specified limits.
• Assumption and implications of exponential distribution (independent, identically distributed times to failure) and constant failure rate model.
• Algorithms and spreadsheet-oriented methods for designing and optimizing test plans, plus guidance on plan selection.
• Notes on limits of the standard: it does not substitute for test planning, performance, analysis and reporting guidance (refer to IEC 60300-3-5) nor for test-condition specifications (refer to IEC 60605 series).

Typical use and users

Used by reliability engineers, test laboratories, quality assurance and product-safety teams, engineering managers and standards bodies to design and evaluate statistical reliability tests where a constant failure-rate model is assumed. It supports decision-making about whether observed test results meet contractual or regulatory reliability requirements and is commonly applied in electronics, electrical equipment and other sectors where IEC dependability practices are adopted.

Related standards

Key related documents include IEC 60300-3-5 (guidance on planning, performing, analysing and reporting reliability tests) and the IEC 60605 family (test conditions and procedures for reliability testing); earlier and superseded editions of IEC 61124 (2012, 2006, 1997) are also relevant for history and migration of test plans. National/adopted variants (EN/IEC, BS EN, UNE‑EN, etc.) exist for regional application and tracking changes.

Keywords

Reliability testing; compliance tests; constant failure rate; failure intensity; failure rate; MTTF; MTBF; SPRT; fixed-time/failure tests; test plans; exponential distribution; dependability; TC 56.

FAQ

Q: What is this standard?

A: IEC 61124:2023 is an International Standard titled "Reliability testing - Compliance tests for constant failure rate and constant failure intensity" that defines statistical test procedures and optimized test plans to determine whether observed reliability metrics meet specified requirements under a constant failure‑rate assumption.

Q: What does it cover?

A: It covers the formulation and characterization of optimized test plans (including truncated SPRT, fixed time/failure terminated tests, fixed calendar time tests and combined tests), algorithms for designing those plans (spreadsheet-oriented), and procedures to assess conformity of failure rate, failure intensity, MTTF and MTBF to given requirements, assuming exponential life behavior. It does not provide practical test‑condition specifications or full test planning/reporting procedures.

Q: Who typically uses it?

A: Reliability engineers, test laboratories, QA/product assurance teams, contract test planners, and standards/regulatory bodies engaged in reliability compliance assessment—especially in electrotechnical and related industries—use this standard.

Q: Is it current or superseded?

A: IEC 61124:2023 (Edition 4.0, published 24 February 2023) is the current edition and supersedes IEC 61124:2012 and earlier editions.

Q: Is it part of a series?

A: It is the fourth edition of IEC 61124 and sits within the broader set of IEC dependability/reliability documents (notably IEC 60300 and IEC 60605 families). Regional/adopted versions (EN/IEC, national adoptions) and corrigenda to earlier editions are part of its publication history.

Q: What are the key keywords?

A: Reliability testing; constant failure rate; failure intensity; failure rate; MTTF; MTBF; SPRT; test plans; exponential distribution; dependability.