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

System properties

7.2 Certification

7.2 Certification
The safety functions of the inverter fulfill the following requirements:
● Category 3 to EN 954-1 and ISO 13849-1
● Performance level (PL) d according to EN ISO 13849-1
● Safety integrity level 2 (SIL 2) to IEC 61508
7.3

Probability of failure of the safety functions (PFH value)

The probability of failure of safety functions must be specified by the machine manufacturer
in the form of a PFH value (Probability of Failure per Hour) in accordance with IEC 61508,
IEC 62061, and ISO 13849-1.
The integrated inverter safety functions are only ever part of a complete machine safety
function. A complete safety function comprises the following components, for example:
● A dual-channel sensor for detecting an open protective door.
● A central fail-safe controller for processing the sensor signal further.
● An inverter for safely stopping (SS1) a motor on account of the open protective door.
IEC 62061 explains how to calculate the PFH value for the complete safety function from the
PFH values of the components used for the safety function.
The following applies for the integrated inverter safety function:
Safety function
STO
SS1
SLS
If you need help when evaluating the safety functions of your machine, an online tool for
calculating PFH values is available on the Internet: Safety Evaluation Tool
(www.siemens.com/safety-evaluation-tool).
152
PFH Accounted for in the PFH value
5×10 Complete inverter comprising Control Unit and
-8
Power Module
Safety Integrated Function Manual, SINAMICS G120
Function Manual, 07/2010, FW 4.3.2, A5E03052391B AA