BECKHOFF BC3150 - Manual (Page 20)

Safety Instructions
18 Fieldbus Components
PE power contacts
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.
It should be noted that, for reasons of electromagnetic compatibility, the PE contacts are capacitively coupled to the
mounting rail. This can both lead to misleading results and to damaging the terminal during insulation testing (e.g.
breakdown of the insulation from a 230 V power consuming device to the PE conductor). The PE conductor to the
Bus Coupler / Bus Terminal Controller must be disconnected for the insulation testing. In order to uncouple further
feed locations for the purposes of testing, the feed terminals can be pulled at least 10 mm out from the connected
group of other terminals. In that case, the PE conductors do not have to be disconnected.
The PE power contact must not be used for other potentials.