Siemens SINAMICS G120C USS/MB Operating Instructions Manual page 86

Installing
4.9 Connecting the interfaces for the inverter control
Terminal strips for FSD ... FSF with wiring example
Figure 4-25 Wiring example of the digital inputs with the internal inverter 24 V power supply
All terminals with the reference potential "GND" are connected to each other inside the inverter.
Reference potentials "DI COM1" and "DI COM2" are electrically isolated from "GND".
→ if, as described above, you use the 24‑V power supply from terminal 9 to supply the digital
inputs, then you must connect "GND" with "DI COM1" and "DI COM2" at the terminals.
When an optional 24 V power supply is connected to terminals 31, 32, the inverter remains in
operation even after the Power Module has been disconnected from the line supply. As a
consequence, the inverter maintains fieldbus communication, for example.
→ for terminals 31, 32 only use a 24 VDC power supply with PELV (Protective Extra Low
Voltage).
→ for applications in the USA and Canada: Use a 24 VDC power supply, NEC Class 2.
→ connect the 0 V of the power supply with the protective conductor.
→ if you also wish to use the power supply at terminals 31, 32 for the digital inputs, then you
must connect "DI COM1/2" and "GND IN" with one another at the terminals.
For the analog input, you can use the internal 10 V supply or an external voltage source.
86
Operating Instructions, 09/2017, FW V4.7 SP9, A5E34263257B AF
SINAMICS G120C converter