Siemens SIMATIC ET 200AL System Manual page 42

Connecting
5.3 Operation of the ET 200AL on grounded/non-grounded infeed
Configuring ET 200AL with ungrounded reference potential
When configuring the ET 200AL distributed I/O system with non-grounded reference
potential, occurring interference currents are discharged via an internal RC network to
functional earth (no external connection between 1M and FE).
ET 200AL in the overall configuration
The figure below shows the ET 200AL distributed I/O system in the complete electrical
configuration using the example of an interface module.
①
②
③
④
Figure 5-1
40
Main switch
Short-circuit and overvoltage protection
Fuses for cable protection (automatic circuit breaker for 4 A)
When configuring the ET 200AL distributed I/O system with non-grounded reference potential,
no connection is made between 1M, 2M and FE.
Electrical configuration
Distributed I/O system
System Manual, 08/2021, A5E31861578-AJ