IEC TS 63394:2023 / Guidelines on functional safety of safety-related control system (SRCS)

ID 19524 | 29.04.2023 / Preview in attachment

IEC TS 63394:2023
Safety of machinery - Guidelines on functional safety of safety-related control system (SRCS)

Date: February 2023

In the context of the safety of machinery, the sector standard IEC 62061, along with ISO 13849 1, provides requirements to manufacturers of machines for the design, development and integration of safety-related control systems (SCS) or safety-related parts of control systems (SRP/CS), depending on technology used (mechanical, pneumatic, hydraulic or electrical technologies) to perform safety function(s). This document does not replace ISO 13849-1 and IEC 62061.

This document gives additional guidance to the application of IEC 62061 or ISO 13849-1.

This document:
– gives guidelines and specifies additional requirements for specific safety functions based on the methodology of ISO 12100, which are relevant in machinery and respecting typical boundary conditions of machinery;
– considers safety functions which are designed for high demand mode of operation yet are rarely operated, called rarely activated safety functions;
– gives additional information for the calculation of failure rates using other (non-electronic) technologies based e.g. on Weibull distribution, because all the formula defined in IEC 62061 and ISO 13849-1 are based on exponential distribution.

Therefore, the basis for these guidelines and additional requirements is
– a typical classification of safety functions;
– a consideration of typical architectures used for designing safety functions;
– a consideration of modes of operation of safety functions;
– the derivation and evaluation of PFH formulas for subsystems considering the used technology.

This document does not address low demand mode of operation according to IEC 61508.
This document does not take into account either layer of protection analysis (LOPA) or basic process control system (BPCS), according to IEC 61511 as a risk reduction measure.
This document considers all lifecycle phases of the machine regarding functional safety, and SCS or SRP/CS.
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1 Scope

In the context of the safety of machinery, the sector standard IEC 62061, along with ISO 13849-1, provides requirements to manufacturers of machines for the design, development and integration of safety-related control systems (SCS) or safety-related parts of control systems (SRP/CS), depending on technology used (mechanical, pneumatic, hydraulic or electrical technologies) to perform safety function(s).

This document does not replace ISO 13849-1 and IEC 62061.

This document gives additional guidance to the application of IEC 62061 or ISO 13849-1.

This document:
– gives guidelines and specifies additional requirements for specific safety functions based on the methodology of ISO 12100, which are relevant in machinery and respecting typical boundary conditions of machinery;
– considers safety functions which are designed for high demand mode of operation yet are rarely operated, called rarely activated safety functions;

NOTE 1
IEC 62061:2021 completely covers high demand. However, other safety functions related to the protection of the machine itself and indirectly of persons are considered more in detail in this document.

– gives additional information for the calculation of failure rates using other (non-electronic) technologies based e.g. on Weibull distribution, because all the formula defined in IEC 62061 and ISO 13849-1 are based on exponential distribution.

Therefore, the basis for these guidelines and additional requirements is

– a typical classification of safety functions;
– a consideration of typical architectures used for designing safety functions;
– a consideration of modes of operation of safety functions;
– the derivation and evaluation of PFH formulas for subsystems considering the used technology.

NOTE 2
These guidelines can also be used for application of ISO 13849-1 for the design process of SRP/CS. This document does not address low demand mode of operation according to IEC 61508.

This document does not take into account either layer of protection analysis (LOPA) or basic process control system (BPCS), according to IEC 61511 as a risk reduction measure.

This document considers all lifecycle phases of the machine regarding functional safety, and SCS or SRP/CS.

NOTE 3
The user of the machine needs information from the machine manufacturer for the safe operation of the machine, e.g. useful lifetime of components, maintenance information, testing of safety functions if necessary.
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