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Connecting up
5.3 Grounding
Note
The requirements of EN61000-4-5, "Surge Immunity Test" on power supply lines with 24 VDC are
met only when a Blitzductor is used:
24 VDC: BVT AVD 24 type no. 918 422
Vendor: DEHN+SÖHNE GmbH+Co.KG, Hans Dehn Str. 1, Postfach 1640, D - 92306 Neumarkt,
Germany
Note
External power supply for operation in China
The device may only be used with an external power supply that has a CCC approval.
5.3
Grounding
EMC disturbances are diverted to ground via ground. This increases the immunity of the data
transmission.
It is crucial for the correct operation of ground that the connection to the reference potential
surface always has low impedance. Such a connection of the functional ground of the device
does not go first through the cable channel and then to the mounting plate or DIN rail
terminal, but goes directly to the mounting plate or DIN rail terminal.
The device has a terminal for grounding, refer to section "Power supply (Page 59)" or section
"Terminals (Page 30)".
The terminal is identified by the following symbol for the grounding.
1. Connect the terminal of the device with as short a cable as possible ≤ 150 mm and a large
cross-sectional area ≥ 2.5 mm² to the functional ground of the system. In many cases, the
entire metallic construction of the system serves as ground.
2. Also connect the standard rails of a system with ground.
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.
60
Operating Instructions, 02/2023, C79000-G8976-C331-12
SCALANCE M874, M876
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