Elster EK280, Руководство по применению, Страница: 45 / 163

EK280 Application Manual 43
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In particular, when connecting more than one output to a PLC, it must be taken into
consideration that under normal operating conditions all 4 outputs have a common earth. Inputs
on a PLC often have a common "plus" contact so that all outputs can be switched in parallel.
Impossible interconnections of
outputs to a PLC or an isolation
amplifier with more than one input and
a common plus potential in the device
connected downstream:
Possible correct interconnections:
Isolation amplifiers with common earth: Separate isolation amplifiers for each output
(recommended):
6.9
Isolating outputs (galvanic isolation)
Usually all negative poles of the outputs are electrically connected to the motherboard.
For special applications such as e.g. switching a positive terminal, each output can be electrically kept separate
from the motherboard and from the other outputs.
In addition, interconnecting devices means that unwanted disturbance via ground loops can take place, which
can be prevented by "isolating" outputs which are correspondingly used in such a manner.