BS EN 61810-2:2017 - Electromechanical elementary relays. Reliability

BS EN 61810-2:2017

Electromechanical elementary relays. Reliability

Status : Current   Published : October 2017



This part of IEC 61810 covers test conditions and provisions for the evaluation of endurance tests using appropriate statistical methods to obtain reliability characteristics for relays.

This document applies to electromechanical elementary relays considered as non-repaired items (i.e. items which are not repaired after failure).

The lifetime of a relay is usually expressed in number of cycles (CTF). Therefore, whenever the terms “time” or “duration” are used in IEC 61649, they carry the meaning “cycles”. However, with a given frequency of operation, the number of cycles can be transformed into respective times (e.g. times to failure (TTF)).

The failure criteria and the resulting characteristics of elementary relays describing their reliability in normal use are specified in this document. A relay failure occurs when the specified failure criteria are met.

As the failure rate for elementary relays cannot be considered as constant, particularly due to wear-out mechanisms, the cycles to failure of tested items typically show a Weibull distribution. This document provides numerical and graphical methods to calculate approximate values for the two-parameter Weibull distribution, as well as lower confidence limits and a method for confirmation of reliability values with the WeiBayes method.

This document does not cover procedures for electromechanical elementary relays where enhanced requirements for the verification of reliability apply.


Such reliability test procedures are specified in IEC 61810‑2‑1. In particular, when electromechanical elementary relays are intended to be incorporated in safety-related control systems of machinery in accordance with IEC 62061 and ISO 13849‑1, IEC 61810‑2‑1 defines procedures for the manufacturer to provide B10D values.


Electromechanical elementary relays with forcibly guided (mechanically linked) contacts according to IEC 61810‑3 offer the possibility of a high diagnostic coverage according to 4.5.3 of ISO 13849‑1:2015.

Standard NumberBS EN 61810-2:2017
TitleElectromechanical elementary relays. Reliability
Publication Date24 October 2017
Normative References(Required to achieve compliance to this standard)IEC 61810-1:2015, IEC 61649:2008, EN 61649:2008, EN 61810-1:2015
Informative References(Provided for Information)ISO 3534, ISO 2854:1976, IEC 60300-3-5:2001, IEC 60050-191:1990, IEC 60605-6:2007, EN 61810-3:2015, IEC 61810-3:2015, ISO 13849-1:2015, IEC 61810-2-1:2017, ISO 3534-1:2006, EN 61810-2-1:2017, EN ISO 13849-1:2015, IEC 62061:2005, IEC 60605-4:2001, EN 62061:2005
ReplacesBS EN 61810-2:2011
International RelationshipsCLC/TR 62258-4:2007,EN 61810-2:2017,IEC 61810-2:2017
Draft Superseded By14/30311867 DC
DescriptorsRatings, Analysis, Switches, Test equipment, Data processing, Classification systems, Failure (mechanical), Circuits, Reliability, Testing conditions, Electrical testing, All-or-nothing relays, Statistical methods of analysis, Making capacity, Endurance testing, Relays, Performance testing, Switchgear
Title in FrenchRelais électromécaniques élémentaires Fiabilité
Title in GermanElektromechanische Elementarrelais Funktionsfähigkeit (Zuverlässigkeit)
ISBN978 0 580 87822 0
File Size2.836 MB

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