DC Power Technologies FS3 Version 3 - Technical Hardware Manual - Manual (Page 25)

Page | 24
AC Input Configurations
The figures below show common industrial AC supply types and the
appropriate wire connections to the input terminal strip.
Should connection to another type of supply be required, contact
the local distributor before connecting.
Note: It is common in the US that a fourth wire (neutral) be used in
a three phase circuit. If present, it should be attached to the “E”
(ground) terminal.