Siemens ET 200pro Operating Instructions Manual page 70

Connection
4.2 Operation of the ET 200pro with Grounded Reference Potential
Overall configuration of ET 200pro
The figure below shows the overall configuration of the ET 200pro distributed I/O system
(load voltage supply and grounding concept) with infeed from a TN-S network.
①
②
③
④
⑤
Note
When ET 200pro is operated with ungrounded reference potential and 1M and FE are not
interconnected, any interference currents will be discharged to protective ground via an
internal RC circuit.
Insulation monitoring
Insulation monitoring must be provided in the following cases:
● In an ET 200pro configuration with ungrounded reference potential
● If hazardous plant states can be expected as a result of faults.
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Disconnecting device for control system, signal transmitters and final controlling elements
Short-circuit and overload protection
The connection between 1M and FE is not applicable in an ET 200pro configuration with
ungrounded reference potential.
Ground busbar
Fuses for line protection
ET 200pro distributed I/O system
Operating Instructions, 03/2013, A5E00335544-08