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Protective earth/functional ground
The connection of the reference potential surface with the protective earth system is normally
in the cabinet close to the power feed-in. This earth conducts fault currents to ground safely and
according to DIN/VDE 0100 is a protective earth to protect people, animals and property from too
high contact voltages.
Apart from the protective earth, there is functional grounding in the cabinet. According to
EN60204-1 (DIN/VDE 0113 T1) electrical circuits must be grounded. The chassis (0 V) is
grounded at one defined point. Here, once again the grounding is implemented with the lowest
leakage resistance to ground in the vicinity of the power feed-in.
With automation components, functional ground also ensures interference-free operation of a
controller. Via the functional ground, interference currents coupled in via the connecting cables
are discharged to ground.
Connecting up
4.6 Functional ground
SCALANCE XR-100WG
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Operating Instructions, 09/2020, C79000-G8976-C455-04