6.6
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.
The IE switch has a terminal for functional ground, refer to the section "Power supply
(Page 39)". Keep to the specified cross-sectional area for the functional ground.
The terminal is identified by the following symbol for the functional ground
.
Follow the steps below to connect the functional ground:
1. Connect the terminal of the IE switch with as short a cable as possible ≤ 150 mm and with
the required cross-sectional area to a grounded part of the system (DIN rail).
2. Connect the DIN rail with the ground of the system.
Protective/functional ground
The connection of the reference potential surface with the protective ground system is normally
in the cabinet close to the power feed-in. This ground conducts fault currents to ground safely
and according DIN/VDE 0100 is a protective ground to protect people, animals and property
from too high contact voltages.
Apart from the protective ground, 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
6.6 Functional ground
SCALANCE XB-200
Operating Instructions, 03/2020, C79000-G8976-C359-09
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