Siemens SINAMICS G120 Function Manual page 219

EN ISO 13849-1 is based on the known categories of EN 954-1. It now also takes into
account complete safety functions and all the devices required to execute these. With EN
ISO 13849-1, safety functions are investigated from a quantitative perspective going beyond
the qualitative basis of EN 954-1. Performance levels (PL), which are based on the
categories, are used. The following safety-related characteristic quantities are required for
devices/equipment:
● Category (structural requirement)
● PL: Performance level
● MTTF
● DC: Diagnostic coverage
● CCF:
The standard describes how the performance level (PL) is calculated for safety-related
components of the controller on the basis of designated architectures. In the event of any
deviations from this, EN ISO 13849-1 refers to EN 61508.
When combining several safety-related parts to form a complete system, the Standard
explains how to determine the resulting PL.
Note
Since May 2007, EN ISO 13849-1 has been harmonized as part of the Machinery Directive.
EN 954-1 will continue to apply until 30.12.2011.
A.1.2.5 EN 62061
EN 62061 (identical to IEC 62061) is a sector-specific standard subordinate to IEC/EN
61508. It describes the implementation of safety-related electrical machine control systems
and looks at the complete lifecycle, from the conceptual phase to decommissioning. The
standard is based on the quantitative and qualitative analyses of safety functions,
whereby it systematically applies a top-down approach to implementing complex control
systems (known as "functional decomposition"). The safety functions derived from the risk
analysis are sub-divided into sub-safety functions, which are then assigned to real devices,
sub-systems, and sub-system elements. Both the hardware and software are covered. EN
62061 also describes requirements regarding the implementation of application programs.
A safety-related control systems comprises different sub-systems. From a safety
perspective, the sub-systems are described in terms of the SIL claim limit and PFH
characteristic quantities.
Safety Integrated Function Manual, SINAMICS G120 and G120C
Function Manual, 01/2011, FW 4.4, A5E03052391B AB
: Mean time to dangerous failure
d
Common cause failure
A.1 Standards and specifications
Appendix
D
217