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

System properties

7.2 Certification

Response times when limit values are violated
Table 7- 3
Function
SLS
SDI
SSM
2)
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
the PFH
The following applies for the integrated inverter safety function:
Safety function
STO, SS1, SLS, SDI, SSM
In the Internet we provide a free tool to calculate the PFH
Safety Evaluation Tool (www.siemens.com/safety-evaluation-tool).
210
Response times until a response is initiated
Response
STOP A or STOP B
STOP A or STOP B
Signal change into the "Status SSM"
If you switch on the motor when a safety function is active, the inverter detects a limit value
violation at the earliest after the "delay time actual value acquisition" has expired (p9586, see e.g.
Section: Encoderless actual value sensing (Page 126)).
values of the components used for the safety function.
D
Typical
67 ms
2)
value for the complete safety function from
D
PFH
5×10
value of a complete machine:
D
Safety Integrated Function Manual, SINAMICS G120 and G120C
Function Manual, 01/2011, FW 4.4, A5E03052391B AB
Worst case
113 ms
2)
D
-8