Siemens PM330, Hardware Installation Manual

Page: 126 / 150

Appendix
A.3 Application examples for functional safety (STO / SS1-t)
Power Module PM330
124
Hardware Installation Manual, 12/2018, A5E32844552B AF
A.3.2.2 3SK1 power supply via X9 from the PM330
Figure A-2 3SK1 power supply via X9 from the PM330
Information about the application example
● The 3SK1 is supplied with 24 V DC via the -X9:1/2 terminal strip
● The control of the PM330 is supplied from the integrated power supply.
-> parasitic voltages can occur and/or faults and disturbances can be coupled-in.
Parasitic voltages can occur via the 3SK1 sensor circuit, especially when connecting to
higher-level safety control systems.
In addition, faults can be coupled-in via the input circuit of the 3SK1 at the STO inputs of the
PM330.
-> use a 3SK1 with relay contacts, and ensure consistent electrical isolation, see Chapter
"SIRIUS 3SK1121 with relay outputs (Page 126)".