Connecting the PSSu system
Installation Manual PSSuniversal
21262-EN-07
41
The supply voltages for module supply and periphery supply must be extra low voltages
with protective electrical separation (PELV or SELV) in accordance with VDE 0100, Part
410. Further requirements of the power supplies can be found in the data sheets for the
supply voltage modules or head modules.
When the voltages are fed separately using two power supplies, the module supply and
periphery supply are galvanically isolated. If galvanic isolation is not required, a common
power supply may be used for the periphery supply and module supply.
Separate power supplies for module supply and periphery supply increase availability: In
the case of a short circuit in the periphery supply, the module supply is maintained and the
head module can continue to exchange data with fieldbus systems, e.g. for diagnostic pur-
poses.
WARNING!
Risk of electrocution!
Always connect the mounting rail to the protective earth via an earthing ter-
minal. This will be used to dissipate hazardous voltages in the case of a
fault.
A base-insulated device with a supply voltage of more than 50 VAC or 120
VDC may not be connected parallel to the module supply.
Insulation of supplies in a PSSu installation:
Failsafe
fieldbus
Standard
fieldbus
Module
supply
Relay module
Switch contact 1
Relay module
Switch contact 2
Periphery
supply
C-rail
C-rail
C-rail
Safe separation
Basic insulation
Functional insulation
