IEC 61123-2019 PDF

Full title and description

Reliability testing - Compliance test plans for success ratio. IEC 61123:2019 specifies procedures to verify whether the reliability of an item or system complies with stated requirements expressed as a percentage success (success ratio) or failure (failure ratio). It covers fixed trial/failure-terminated plans and truncated sequential probability ratio tests (SPRTs), and includes extensive ready-to-use SPRT tables and guidance for practical design and interpretation of compliance tests.

Abstract

This second edition (2019) revises and extends the original 1991 edition. It provides statistical test plans for reliability compliance where trials are treated as statistically independent, offers truncated SPRT plans with accurate expected number of trials (ENT) data, accounts for unequal supplier/customer risks, and adds practical guidance such as using the cumulative binomial distribution in common tools (e.g., Excel). The standard is intended to streamline practical reliability decision testing while keeping producer’s and consumer’s risks near nominal values.

General information

• Status: Published / Current (stable reference date indicated to 2028).
• Publication date: 22 November 2019.
• Publisher: International Electrotechnical Commission (IEC).
• ICS / categories: 03.120.01, 03.120.30, 21.020.
• Edition / version: Edition 2.0 (2019).
• Number of pages: 98 pages.

Scope

IEC 61123:2019 specifies procedures for preparing and applying compliance test plans when requirements are expressed as a success or failure proportion. It applies where a defined number of trials are classified pass/fail or where items are subjected to repeated trials. The standard assumes statistical independence of trials and provides plans for both fixed trial/failure-terminated testing and truncated SPRTs, together with tables and guidance for selecting plans across a wide range of discrimination ratios and producer/consumer risk combinations. For compliance tests specifically concerned with constant failure rate/intensity, IEC 61124 is referenced.

Key topics and requirements

• Definitions and statistical assumptions for success/failure testing (independent Bernoulli trials).
• Fixed trial and fixed-failure terminated test plans for compliance assessment.
• Truncated Sequential Probability Ratio Tests (SPRTs) with ready-to-use tables and characteristics (ENT, true risks, truncation limits).
• Provision for unequal supplier (producer) and customer (consumer) risks and various risk ratios.
• Guidance for extension of test sets (interpolation/extrapolation) and practical computation methods (including use of cumulative binomial functions in spreadsheets).
• Relationship and normative references to other dependability/reliability standards (historical and related documents).

Typical use and users

Used by reliability engineers, quality assurance and test laboratories, product manufacturers, certification and conformity assessment bodies, and statisticians designing or evaluating reliability compliance testing. Typical applications include acceptance testing of components or systems where pass/fail criteria are specified, supplier-customer contractual testing, and product type testing where decision-making must balance producer and consumer risks.

Related standards

References and relationships include the original IEC 61123:1991 (superseded), earlier IEC/ISO statistical reliability standards such as IEC 60605 series and IEC 61124 (for constant failure rate/intensity tests). The standard sits within the dependability work of IEC TC 56 and is commonly published as EN IEC 61123 in regional adoptions.

Keywords

Reliability testing, compliance test plans, success ratio, failure ratio, SPRT, sequential probability ratio test, fixed-trial tests, producer’s risk, consumer’s risk, expected number of trials (ENT), statistical acceptance testing.

FAQ

Q: What is this standard?

A: IEC 61123:2019 is an international standard that provides procedures and ready-to-use plans to assess whether an item or system meets stated reliability requirements expressed as a success or failure proportion.

Q: What does it cover?

A: It covers statistical test designs for pass/fail trials, including fixed trial/failure-terminated plans and truncated SPRTs, tables for practical use, guidance on producer/consumer risks, and methods to compute test characteristics (including spreadsheet approaches). It does not replace specific constant-failure-rate procedures covered by IEC 61124.

Q: Who typically uses it?

A: Reliability engineers, QA/test labs, manufacturers, conformity assessors, and statisticians involved in designing, running or interpreting reliability compliance tests.

Q: Is it current or superseded?

A: The 2019 edition (Edition 2.0) is the current edition and it cancels and replaces the first edition (1991). The IEC webstore indicates a stability reference date (stability to 2028).

Q: Is it part of a series?

A: It is part of IEC TC 56 (Dependability) work and relates to other dependability/reliability standards (for example IEC 61124 for constant failure rate testing and earlier IEC/ISO statistical test method standards). Regional adoptions may appear as EN IEC 61123.

Q: What are the key keywords?

A: Success ratio, failure ratio, SPRT, fixed-trial test, producer’s risk (α), consumer’s risk (β), expected number of trials (ENT), compliance test plan.