Siemens PM330, Hardware Installation Manual

Page: 112 / 150

Safety functions of PM330
8.2 Safety functions that can be implemented
Power Module PM330
110
Hardware Installation Manual, 12/2018, A5E32844552B AF
8.1.2 PM330 application with safety relay
Using an appropriate PM330 application with a suitable safety relay (e.g. 3SK1), for the
complete safety function, a Safety Integrity Level of 3 (SIL 3) according to EN 61800-5-2 or a
Performance Level e (PL e) including Category 4 (Cat. 4) according to EN ISO 13849-1 can
be achieved.
Achieving safety integrity level 3 (SIL 3) - or Performance Level e (PL e) including
Category 4 (Cat. 4) - depends directly on the selected application and the test stop interval,
see "Relationship between the test stop interval and SIL or PL and Cat. (Page 114)" and
"Application examples for functional safety (STO / SS1-t) (Page 121)".
To achieve the diagnostics required for SIL 3 or PL e, Cat. 4, it is sufficient to integrate the
two feedback signal contacts into the feedback circuit of a basic safety relay (e.g. 3SK1).
A fixed hardware filter in the two STO input circuits (
≤ 4 ms) is used to filter out noise and
brief signal changes - e.g.as a result of light and dark tests of the safety relays or as a result
of contact bounce.
All safety-relevant signals, STO inputs as well as feedback signals of the switch-off signal
paths are connected to the safety interface -X41, which means that they can be controlled
and/or evaluated using external safety relays.
8.2 Safety functions that can be implemented
STO
Figure 8-1 Safe Torque Off (STO)
The safety subfunction "React" is implemented in the PM330 Power Module, which in turn
implements the safe shutdown response of the STO function.
This means that an STO function can be completely implemented using evaluation and
monitoring devices (e.g. safety relay, F-PLC) connected at the safety interface -X41.