Siemens Assembling an S7-400 with Grounded Reference Potential M, Application

Wiring the S7-400

4.5Assembling an S7-400 with Grounded Reference Potential (M)

Application

You use an S7-400 with grounded reference potential in machines or industrial plants.

Discharge of Interference Currents

When the S7-400 is configured with a grounded reference potential, any interference currents are discharged to the chassis ground.

Terminal Connection Model

When delivered, the racks have a detachable metallic connection between the internal reference potential M of the modules and the frame element of the racks. Situated behind this connection is an RC network which is placed in the circuit for the ungrounded configuration. This connection is located at the left edge of the rack. The terminal for the chassis ground also has an electrical connection to the frame element.

Shown in Figure 4-2 is an S7-400 configured with grounded reference potential. To ground the reference potential M, you must connect the chassis ground terminal to the chassis ground and you must not remove the jumper between reference potential M and the frame element terminal on the rack.

RC network

Detachable jumper

6.8 nF 10 MΩ

M

Frame element terminal

Metallic connection

Reference potential M

Chassis ground terminal

Figure 4-2 An S7-400 Configured with Grounded Reference Potential

Automation System S7-400	Hardware and Installation	4-7
A5E00850741-01