Wiring the S7-400
4-13
S7-400 and M7-400 Programmable Controllers, Installation Manual
C79000-G7076-C424-01
4.8 Assembling an S7-400 with Isolated Modules
Definition
In a configuration with isolated modules, the reference potentials of the control
circuit (0 V
internal
) and the load circuit 0 V
external
) are isolated (see also Figure 4-4).
Application
Isolated modules are used for:
All AC load circuits
DC load circuits with a separate reference potential
Examples of load circuits with a separate reference potential:
– DC load circuits whose sensors have different reference potentials (for
example, when grounded sensors are used far from the programmable
controller and equipotential bonding is not possible).
– DC load circuits whose positive terminal (L+) is grounded (battery circuits).
Isolated Modules and Grounding Concept
You can use isolated modules, regardless of whether or not the reference potential
of the programmable controller is grounded.
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