En 62061 - Siemens SINAMICS V90 Operating Instructions Manual

8.1.2.5

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 life cycle, 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 the requirements placed on implementing application programs.
A safety-related control system comprises different sub-systems. From a safety perspective,
the sub-systems are described in terms of the SIL claim limit and PFHD characteristic
quantities.
Programmable electronic devices (e.g. PLCs or variable-speed drives) must fulfill EN 61508.
They can then be integrated in the controller as sub-systems. The following safety-related
characteristic quantities must be specified by the manufacturers of these devices.
Safety-related characteristic quantities for subsystems:
● SIL CL: SIL claim limit
● PFHD: Probability of dangerous failures per hour
● T1: Lifetime
Simple sub-systems (e.g. sensors and actuators) in electromechanical components can, in
turn, comprise sub-system elements (devices) interconnected in different ways with the
characteristic quantities required for determining the relevant PFHD value of the sub-system.
Safety-related characteristic quantities for subsystem elements (devices):
● λ: Failure rate
● B10 value: For elements that are subject to wear
● T1: Lifetime
For electromechanical devices, a manufacturer specifies a failure rate λ with reference to the
number of operating cycles. The failure rate per unit time and the lifetime must be
determined using the switching frequency for the particular application.
Parameters for the sub-system, which comprises sub-system elements, that must be defined
during the design phase:
● T2: Diagnostic test interval
● β: Susceptibility to common cause failure
● DC: Diagnostic coverage
SINAMICS V90, SIMOTICS S-1FL6
Operating Instructions, 07/2015, 6SL3298-0AV60-0BP0
Safety Integrated function
8.1 Standards and regulations
207