IEC 60744:2018 provides requirements and recommendations for the design, construction and test of safety logic assemblies used in safety systems to perform category A safety functions (in accordance with IEC 61226). Safety logic assemblies include logic such as the hardwired logic assembly interfacing computer-based systems to switchgear, actuators or contactors to provide trip or engineered safety feature actuations. Safety logic assemblies are significant parts of a safety system and may include voting logic between redundant channels. This document provides a general description of safety logic assemblies for safety actuators control. The principles to meet dependability objectives are presented. The main features relating to the design requirements are described and explained.
This new edition includes the following significant technical changes with respect to the previous edition:
a) update of the references to standards published or revised since the issue of the first edition of the current standard, including IEC 61513 and IEC 61226;
b) additional requirements for operational and maintenance bypass use; requirements of voting logic; and others.