Siemens Simatic S7-400 - Manual (Page 104)

Power Supply Modules
3-24
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Power Connection
In contrast to the instructions on installing a power supply module described in the
“S7-400, M7-400 Programmable Controllers, Hardware and Installation” manual,
an AC connector is used for connecting the PS 407 10A and the PS 407 10A R to
both an AC and a DC supply.
Polarity Reversal of L+ and L-
The polarity reversal of L+ and L- with supply voltages of between 88 VDC
and 300 VDC has no effect on the function of the power supply. The connection
should be made as described in the instructions in the Installation Manual,
Chapter 6.