Siemens SINUMERIK 840D sl Function Manual page 22

Regulations and standards
2.2 Machine safety in Europe
Safety-related characteristic quantities for subsystems:
● SIL CL: SIL suitablility
● PFH
● T1:
Basic subsystems, e.g. sensors and actuators comprising electromechanical components,
can, in turn, comprise different interconnected subsystem elements (devices) with the
characteristic quantities to determine the corresponding PFH
Safety-related characteristic quantities for subsystem elements (devices):
● λ:
● B10 value:
● T1:
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 subsystem, which comprises subsystem elements, that must be defined
during the design phase:
● T2:
● β:
● DC:
The PFH
PFH
The user has the following options when setting up a safety-related control system:
● Using devices and subsystems that already comply with EN ISO13849-1 or EN 61508 and/
or 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 EN 61508 or
– Simple devices and subsystems: Application of EN 62061.
22
SIL claim limit
: Probability of hazardous failures per hour
D
Probability of dangerous failure per hour
Service life
Lifetime
Failure rate
Failure rate
for elements that are subject to wear
Service life
Lifetime
Diagnostic test interval
Diagnostic test interval
Sensitivity for common cause faults
susceptibility to common cause failure
Diagnostics coverage
Diagnostic coverage
value of the safety-related control system is determined by adding the individual
D
values for subsystems.
D
EN 61800-5-2.
value of the subsystem.
D
Function Manual, 12/2017, 6FC5397-4BP40-6BA1
Safety Integrated