Beckhoff KL2904 Operating Instructions Manual page 27

Note the connection of the power contacts
During the design of a bus terminal block, the pin assignment of the individual bus terminals must
be taken account of, since some types (e.g. analog bus terminals or digital 4-channel bus terminals)
do not or not fully loop through the power contacts.
Power supply terminals (KL91xx, KL92xx) interrupt the power contacts and thus represent the start
of a new supply rail.
PE power contact
The power contact labelled PE can be used as a protective earth. For safety reasons this contact mates first
when plugging together, and can ground short-circuit currents of up to 125 A.
Fig. 8: PE power contact
Insulation tests
Note that, for reasons of electromagnetic compatibility, the PE contacts are capacitatively coupled to the
mounting rail. This may lead to incorrect results during insulation testing or to damage on the terminal (e.g.
disruptive discharge to the PE line during insulation testing of a consumer with a nominal voltage of 230 V).
For insulation testing, disconnect the PE supply line at the Bus Coupler or the Power Feed Terminal! In
order to decouple further feed points for testing, these Power Feed Terminals can be released and pulled at
least 10 mm from the group of terminals.
Serious risk of injury!
The PE power contact must not be used for other potentials!
5.2.4.2 Overvoltage protection
If protection against overvoltage is necessary in your plant, provide a surge filter for the voltage supply to the
Bus Terminal blocks and the TwinSAFE terminals.
KL2904
CAUTION
DANGER
Version: 3.1.0
Operation
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