Siemens SIMATIC NET SCALANCE S615 - Page 50

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
5.3 Grounding
EMC disturbances are diverted to ground via the functional ground. This increases the immunity
of the data transmission.
It is crucial for the correct operation of functional 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 󹪝rst 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 SCALANCE S615 has a terminal for functional ground, refer to the section "Terminals
(Page23)“ and section “Power supply (Page49)“.
The terminal is identi󹪝ed by the following symbol for the functional ground.
1. Connect the terminal of the SCALANCE S615 with as short a cable as possible ≤ 150 mm and
a large cross-sectional area of 1.5 mm² to the functional ground of the system. In many cases,
the entire metallic construction of the system serves as functional ground.
2. Also connect the standard rails of a system with functional 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 de󹪝ned 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.
In terms of the large-area and low impedance implementation, a functional ground set up for
this purpose generally also meets the requirements of protective earth. On the other hand,
protective earth does not always meet the requirements of functional ground. In general
Connecting up
5.3Grounding
SCALANCE S615
50 Operating Instructions, 05/2023, C79000-G8976-C389-08