Siemens S5-135U/155U appendix Installation Guidelines

Installation Guidelines

3.5Interference-Free Installation of Centralized and Distributed Interface Circuits

Subjects described in the following sections are the shielding and grounding concept with centralized and distributed interface circuits.

Information on component selection, the mechanical arrangement and wiring can be found in the appropriate reference manuals for the interface modules.

Note

If you use components which are not approved for the installation of a centralized or distributed interface circuit, interference rejection may be impaired.

3.5.1Interference-Free Installation of Centralized Interface Circuits

When you connect the central controller and expansion unit centrally via suitable interface modules, no particular shielding and grounding measures are required. Ensure, however, that

Sall subracks are interconnected at a low resistance;

Sthe subracks in a grounded arrangement have star-configuration grounding;

Sthe contact springs of the modules are clean and not bent, which could affect the path to ground for interference currents.

3.5.2Interference-Free Installation of Distributed Interface Circuits

If you interconnect the central controller and expansion unit in a distributed arrangement using suitable interface modules, no particular shielding and grounding measures are usually required. Only in industrial environments with an extremely high level of interference is there a need for special shielding and grounding.

In these cases, please observe the following points:

SCable shields should be connected to the shield bar in the cabinet, immediately after the cable inlet;

-insulation is fully stripped from the cable for the purpose;

-braided shields are secured to the shield bar with as large an area as possible (e.g. with metal ties which enclose the shield over a large area).

SShield bars should be connected to the frame or cabinet panel over a large area.

SCable shields should be connected to the cabinet conductor.

3-28	System Manual
	C79000-G8576-C199-06