Proface PS4800 - 19 Panel PC" - Manual (Page 65)

Main Power Connection
65
Shared Ground not Allowed
Do not connect the PS-B unit to ground through other devices using the SG
terminals.
Shared Ground - Avoid Ground Loop
When connecting an external device to a PS-B unit with the Shield Ground (SG),
ensure that no ground loop is created. The PS-B unit’s FG and SG are connected
internally.
Other
Device
Other
Device
PS-B unit
Other
Device
Other
Device
PS-B unit
Other
Device
Other
Device
PS-B unit