Siemens SINAMICS G120 Function Manual page 324

Appendix
A.3 Standards and specifications
Safety-related characteristic quantities for subsystems:
● SIL CL: SIL claim limit
● PFH
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 PFH
Safety-related characteristic quantities for subsystem elements (devices):
● λ:
● 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:
● β:
● DC:
The PFH
values for subsystems.
The user has the following options when setting up a safety-related controller:
● Use devices and sub-systems that already comply with EN ISO 13849-1, IEC/EN 61508,
or IEC/EN 62061. The standard provides information specifying how qualified devices
can be integrated when safety functions are implemented.
● Develop own subsystems:
– Programmable, electronic systems and complex systems: Application of IEC 61508 or
– Simple devices and subsystems: Application of EN 62061.
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Failure rate
Diagnostic test interval
Susceptibility to common cause failure
Diagnostic coverage
value of the safety-related controller is determined by adding the individual PFH
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IEC 61800-5-2.
Safety Integrated - SINAMICS G110M, G120, G120C, G120D and SIMATIC ET 200pro FC-2
value of the sub-system.
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Function Manual, 04/2014, FW V4.7, A5E34261271B AA
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