Wiring
5-9
Distributed I/O Device ET 200M
EWA-4NEB780600602-06
5.1.3
Configuring the ET 200M with Ungrounded Reference Potential
When the ET 200M is configured with ungrounded reference potential, any
interference current is diverted to the protective conductor via an RC network
integrated in the IM 153-x (see Figure 5-3).
See also Section 9.3 for older IM 153-x versions.
Application
In plants covering large areas, it may be necessary to configure the ET 200M with
ungrounded reference potential for ground fault monitoring purposes, for example.
This is the case, for instance, in the chemical engineering industry and in power
stations.
Terminal Connection Model
Figure 5-3 shows the configuration of an ET 200M with the IM 153-x with
ungrounded reference potential. If you do not want to ground the reference
potential, you must remove the jumper on the IM 153-x between the M terminals
and functional ground. If the jumper is not in place, the reference potential of the
ET 200M is connected internally to the protective conductor via an RC combination
and via the rail. This discharges radio-frequency interference current and precludes
static charges.
24 V DC
M
L
+
M
Ground bus
M
22 nF
10 M
Ω
Figure 5-3
Configuring the ET 200M with ungrounded reference potential
Power Supply Units
In the case of power supply units, make sure that the secondary winding has no
connection to the protective conductor. We recommend the use of the PS 307
power supply module.
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