Wiring
5-10
Distributed I/O Device ET 200M
EWA-4NEB780600602-06
Filtering the 24V DC Supply
If you supply the IM 153-x from a battery without grounding the reference potential,
you must suppress interference on the 24 V DC supply. Use an interference
suppression device from Siemens such as B84102-K40.
Insulation Monitoring
If dangerous plant conditions can arise as a result of double faults, you must
provide some form of insulation monitoring.
5.1.4
Configuring the ET 200M with Galvanically Isolated Modules
Definition
In configurations with isolated modules, the reference potentials of the control
circuit (M
internal
) and load circuit (M
external
) are electrically isolated (see also Figure
5-4).
Application
You use isolated modules for the following:
All AC load circuits
DC load circuits with separate reference potential, e.g.:
– DC load circuits whose sensors have different reference potentials (for
example, if grounded sensors are located at some considerable distance
from the control system and no equipotential bonding is possible)
– DC load circuits whose positive pole (L+) is grounded (battery circuits).
Isolated Modules and Grounding Concept
You can use isolated modules irrespective of whether the reference potential of the
ET 200M is grounded or not.
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