The power supplies supply the S7-400 modules with their 5 V DC and 24 V DC operating voltages via the backplane bus.

Power supplies are available for AC line voltages of 85 to 264 V and for DC voltages of 19.2 to 300 V.

One power supply module is required per rack.
Exception:
With interfaces with current transfer, the power supply module in the central controller also supplies all modules in the expansion units.

The load voltage for supplying sensors and actuators must be made available separately.

There are also power supplies to make both the standard system and the H system fail-safe (redundant power supplies).