Kendrion Kuhnke Automation GmbH
System Description
21
17 May 2021
System Power Supply
A system connector supplies the Kuhnke FIO Safety I/O system with system power from an upstream
bus coupler or a compact controller. This system power supply is used for the analysis circuitry and for
bus communication only.
Information
Please also note the connection printing on the device before the electrical installation.
WARNING
Potentially hazardous failures due to wrong voltages supplied
Supplying the wrong voltages may damage or destroy the unit and may provoke potentially
hazardous failures.
Preventive measures:
We recommend to use PELV/SELV-ready power supply units to EN50178 or EN60950-1
to supply 24 VDC to bus couplers or compact PLCs.
Only use the GND terminal to connect the power supply unit to earth (PELV system). Do
not use earthing variants that connect earth to +24V.
Remember that, even in case of a fault, a maximum voltage of U max. < 33 V maybe
supplied to these assemblies. If you cannot rule out this risk, external protection of the
power supply is mandatory.
To ensure that there is as little interference as possible, install a central power supply
point and establish a star topology of as short wires as possible between the central point
and the block of FIO modules.
Earth
Connect the Kuhnke FIO modules to earth by attaching the metal housing to functional earth.
Since the functional earth connector dissipates HF currents, it is of utmost importance for the module's
noise immunity.
HF interference is dissipated from the electronics board to the metal housing. The metal housing
therefore needs to be suitably connected to a functional earth connector.
You will normally have to ensure that
the connection between module housing and DIN rail conducts well,
the connection between DIN rail and switching cabinet conducts well,
the switching cabinet is safely connected to earth.