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Connecting up
4.6 Functional ground
Functional ground
EMC disturbances are diverted to ground via the functional ground. This ensures the
immunity of the data transmission.
The functional ground must be implemented with low impedance. The connection of the
functional ground must be established directly on the mounting plate or the DIN rail terminal.
Connecting up functional ground
①
②
To connect the functional ground, use a copper cable of category 20 AWG or a cable with a
cross-section ≥ 0.75 mm
Follow the steps below to connect the functional ground:
1. Loosen the grounding screw.
2. Put the grounding terminal
drawing.
3. Tighten the grounding screw
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.
28
Grounding terminal with cable
Grounding screw with spring washer and washer
.
2
①
, and the grounding screw
②
with a maximum tightening torque of 1.5 Nm.
Operating Instructions, 05/2017, C79000-G8976-C455-01
②
together as shown in the
SCALANCE XR-100WG
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