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4.3
Operation with ungrounded reference potential
Application
In large–scale systems you may have to install the RS 485-IS Coupler with
ungrounded reference potential, for example, for monitoring short–circuit to
ground. This applies in particular to systems operated in the chemical industry or in
power plants, for example.
Discharging Parasitic Currents
In RS 485-IS Coupler installations with ungrounded reference potential, developing
parasitic currents are discharged to protective ground via an integral capacitor (see
Figure 4).
Wiring Diagram
Figure 4 shows an installation of the RS 485-IS Coupler with ungrounded reference
potential. If you choose not to ground the reference potential of the 24 V power of
your RS 485-IS Coupler, you need to remove the jumper between the M
terminals and system ground. As long as this jumper is removed, the reference
potential of the RS 485-IS Coupler is connected internally to the profile rail and the
grounding conductor via a capacitor.
Figure 4
Product Information RS 485-IS Coupler (6ES7 972-0AC80-0XA0)
A5E00207628-02
Equipotential Bonding (EB)
Installing the RS 485-IS Coupler with Ungrounded Reference Potential
22 nF
M
M
L
M
+
11
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