Siemens Simatic ET 200S Operating Instructions Manual page 314

Interference-free operation
F.1 Special Measures for Interference-Free Operation
Example
The following diagram shows an output circuit which makes additional overvoltage protection
devices necessary.
Figure F-1
①
②
Wiring of DC-operated coils
The figure below shows DC-operated coils wired with diode or Zener diode circuits
①
②
F-2
Relay contact for Emergency OFF in the output circuit.
Contact in the output circuit
Inductance requires a circuit (see figures below)
1
with diode
with Zener diode
1
2
2
Operating Instructions, 12/2005, A5E00515771-03
ET 200S