scope:

This part of IEC 61508 contains the definitions and explanation of terms that are used in parts I to 7 of this standard.

The definitions are grouped under general headings so that related terms can be understood within the context of each other. But it should be noted that these headings are not intended to add meaning to the definitions, and in this sense the headings should be disregarded.

Parts 1, 2, 3 and 4 of this standard are basic safety publications, although this status does not apply in the context of low complexity E/E/PE safety-related systems (see 3.4.4 of part 4). As basic safety publications, they are intended for use by technical committees in the preparation of standards in accordance with the principles contained in 1/33 Guide 104 and ISO/IEC Guide 57. Parts 1 2, 3, and 4 are also intended for use as stano-alone publication.

One of the responsibilities of a technical committee is, wherever applicable, to maw use of basic safety publications in the preparation of its publications. In this context, the requirements, test methods or test conditions of this basic safety publication will not apply unless specifically referred to or included in the publications prepared by those technical committees.

Figure I shows the overall framework for parts 1 to 7 of IEC 61508 and indicates the role that IEC 61508-4 plays in the achievement of functional safety for EIEIPE safety-related systems.

NOTE - In the USA and Canada, until the proposed process sector implementation of IEC 61508 (¡.e. IEC 61511) is published as an international standard in the USA and Canada, existing national process safety standards based on IEC 61508 (¡.e. ANSI/ISA S84.01-1996) can be applied to !he process sector instead of IEC 61508.