Siemens Automation System S7-400 Manual do Utilizador descarregar pdf (Página 70)

Wiring the S7-400

4-10

Automation System S7-400 Hardware and Installation

A5E00850741-01

4.7 Assembling an S7-400 with Isolated Modules

Definition

In a configuration with isolated modules, the reference potentials of the control

circuit ( M

internal

) and the load circuit (M

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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