Potential Equalisation; Connection Examples - Festo CPX System Manual

3. Installation
Connection example 1
3−20

Potential equalisation

The CPX terminal has two earthing connections for potential
equalisation:
The functional earth" pin from system supply, additional
supply or valve supply (see Tab. 3/4)
Earth connection on the left−hand end plate (see Fig. 3/4).
Note
Always connect the functional earth" to the earth po
·
tential.
Connect the earth connection of the left−hand end plate
·
to the earth potential with low impedance (short cable
with large cross−sectional area).
With low−impedance connections you can ensure that
·
the earth connection at the left−hand end plate and the
earth connection at the supplies have the same potential
and that there are no equalising currents.
You can thereby avoid interference from electromagnetic
sources and ensure electromagnetic compatibility in accor
dance with EMC directives.

Connection examples

Fig. 3/4 shows as an example the connection of a common
24 V supply for pin 1 and pin 2 on the M18 plug. Please note
that:
The tolerance of 24 V DC ±25 % must be observed.
Both connections for potential equalisation are connected
and that compensating currents must be prevented
The load voltage at pin 2 of the M18 plug (valves and out
puts) can be switched off separately
External fuses are used, depending on the application
(maximum value at pin 0 V" in total for both fuses: 16 A)
Festo P.BE−CPX−SYS−EN en 0902e