System Properties; Probability Of Failure Of The Safety Functions (Pfh Value) - Siemens SINAMICS G120 Function Manual

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System properties

8.1

Probability of failure of the safety functions (PFH value)

The specified probability of failure values apply under the following preconditions:
● The service life of the inverter has not expired.
● The test interval has not expired.
Service life
You may not operate inverters with integrated safety functions for longer than 20 years. The
20 years starts when the device is delivered. The service life cannot be extended. This is the
case even if a service department checks the inverter – or in the meantime, the inverter was
decommissioned.
Test interval
You must test the safety-related circuits of the inverter at least once every year. This process
is called "forced dormant error detection" or "test stop".
Information on the procedure can be found in Section: Regularly testing the safety functions
(Page 161).
Probability of failure
Table 8- 1
Safety function
STO, SBC
1)
PFH according to IEC 61800-5-2, PFH
2)
3)
The machine manufacturer must specify a probability of failure in the form of a PFH value for
every safety function of a machine.
Safety Integrated - SINAMICS G110M, G120, G120C, G120D and SIMATIC ET 200pro FC-2
Function Manual, 04/2014, FW V4.7, A5E34261271B AA
Probability of failure of the safety functions
, SS1, SLS, SDI, SSM
3)
PFH, PFH
: Probability of dangerous failures per hour.
D
PFD: For a low demand rate of the safety function: Mean probability of dangerous failure when the
safety function is demanded according to IEC 61508.
Including Safe Brake Relay
PFH, PFH
5×10
according to IEC 62061.
D
PFD
D 1)
1/h
5×10
-8
8
2)
-3
267

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