Siemens SIMATIC NET S7-300 Operating Instructions Manual page 27

Power supply
The device is designed for operation with a directly connectable safety extra low voltage (SELV)
from a limited power source (LPS).
The power supply therefore needs to meet at least one of the following conditions:
• Only safety extra low voltage (SELV) with limited power source (LPS) complying with IEC
• The power supply unit for the device must meet NEC Class 2 according to the National
If the equipment is connected to a redundant power supply (two separate power supplies),
both must meet these requirements.
Compact Switch Module CSM 377
Operating Instructions, 06/2022, A2B00073499-02
WARNING
60950‑1 / EN 60950‑1 / VDE 0805‑1 or IEC 62368-1 / EN 62368-1 / VDE 62368-1 may be
connected to the power supply terminals.
Electrical Code (r) (ANSI / NFPA 70).
Installation
4.4 Power supply
27