IEC TR 61117-1992 PDF

Full title and description

IEC TR 61117:1992 — A method for assessing the short-circuit withstand strength of partially type-tested assemblies (PTTA). This technical report describes an extrapolation method to apply to type tests in order to assess the short-circuit withstand strength of partially type-tested low-voltage assemblies and gives conditions for its application.

Abstract

This technical report provides a practical extrapolation procedure and guidance for deriving the short-circuit withstand capability of partially type-tested assemblies (PTTA) from existing type-test results. It is informative in nature and intended to support conformity assessment and design decisions where full type-testing of every assembly variant is not performed. The report also identifies limits and conditions under which the extrapolation method may be applied.

General information

• Status: Withdrawn (was published as an IEC Technical Report).
• Publication date: 15 February 1992 (Edition 1.0).
• Publisher: International Electrotechnical Commission (IEC).
• ICS / categories: 29.130.20 (Low-voltage switchgear and controlgear).
• Edition / version: 1.0 (1992).
• Number of pages: 13 (technical report length as published).

Scope

Specifies an extrapolation methodology to estimate short-circuit withstand strength for assemblies that are partially type-tested, including the assumptions, required input data from type tests, application conditions and limitations. The report is intended to support compliance demonstrations with the relevant IEC assembly requirements (historically referenced alongside IEC product/assembly requirements such as IEC 439-1 and later-generation assembly standards). It does not replace full type-testing where that is explicitly required and identifies cases where conservative design or additional testing is necessary.

Key topics and requirements

• Definition and scope of Partially Type-Tested Assemblies (PTTA) and relevant terminology.
• Step-by-step extrapolation method to derive short-circuit withstand strength from type-test results.
• Required input data from existing type tests and acceptable test configurations for extrapolation.
• Conditions, limitations and conservative factors to be applied when extrapolating results.
• Guidance on when additional testing is required instead of extrapolation.
• Informative examples and application notes for manufacturers and test laboratories.

Typical use and users

Used by manufacturers of low-voltage switchgear and controlgear assemblies, design engineers, testing laboratories, certification and conformity-assessment bodies, and regulatory/standards committees to assess short-circuit performance where assemblies are derived from a type-tested design. It is particularly relevant during product development, type-test planning and certification workflows for series-built assemblies.

Related standards

Closely related to IEC product/assembly standards dealing with low-voltage switchgear and controlgear assemblies (historically referenced alongside IEC 439-1 and the IEC 60439 family). The IEC 61439 series (published later) modernized assembly rules and verification methods and changed the approach to verification of assemblies (eliminating some distinctions between TTA and PTTA in favour of verification by testing, calculation/measurement or design rules). Users should consult the applicable current assembly standard (for example IEC 61439 parts) for up-to-date verification rules.

Keywords

PTTA, partially type-tested assemblies, short-circuit withstand strength, extrapolation method, low-voltage switchgear, technical report, IEC TR 61117:1992.

FAQ

Q: What is this standard?

A: IEC TR 61117:1992 is a Technical Report that provides a method for assessing the short-circuit withstand strength of partially type-tested assemblies (PTTA). It is informative guidance rather than a mandatory product standard.

Q: What does it cover?

A: It covers an extrapolation procedure that uses existing type-test results to estimate the short-circuit withstand capability of related assembly variants, plus the conditions and limitations for applying that procedure.

Q: Who typically uses it?

A: Manufacturers, test laboratories, certification bodies and design engineers involved with low-voltage switchgear and controlgear assemblies use this guidance when they have partially type-tested series and need to assess short-circuit strength without repeating exhaustive tests on every variant.

Q: Is it current or superseded?

A: IEC TR 61117:1992 has been withdrawn (the IEC record shows the report was withdrawn in 2012). Additionally, the IEC assembly standards for low-voltage switchgear have evolved (IEC 60439 and earlier IEC 439 series have been superseded by the IEC 61439 family), which changed verification approaches for assemblies. Users should refer to the current IEC 61439 series and the applicable national/adopted standards for present verification rules.

Q: Is it part of a series?

A: The report is associated with the body of IEC work on low-voltage switchgear and controlgear assemblies (technical committee SC 121B). It should be considered in the historical context of IEC 439/IEC 60439 family documents and the later IEC 61439 series that now provide the primary assembly verification framework.

Q: What are the key keywords?

A: PTTA, partially type-tested assemblies, short-circuit withstand, extrapolation method, low-voltage switchgear, IEC TR 61117:1992.