Shielding Of Devices And Cables - Siemens S5-100U User Manual

Installation Guidelines
3.4.2

Shielding of Devices and Cables

Shielding is a means of weakening or damping magnetic, electrical, or electromagnetic interference
fields. Both devices and cables should be shielded.
Shielding of Devices
Use the following information if cabinets and housing are used in shielding the control system.
• Cabinet enclosures, such as side walls, back walls, top plates, and bottom plates, should be
bonded at certain intervals (e.g., 50 mm/2 inches) when you have an overlapping layout.
• Doors need additional bonding to the cabinet's chassis ground. Use wide grounding strips.
• The cables that exit the shield housing should either be shielded or filtered.
• Sheet metal must be used to separate strong interference sources located in the cabinet
(transformers, cables leading to motors, etc.) from sensitive electronic areas. The multiple
screw connections of the sheet metal to the cabinet's chassis ground must have a low
impedance.
The noise interference coming into the programmable controller via the signal cables and supply
lines must be discharged on the central grounding point (standard mounting rail).
Use a low impedance copper conductor, 10 mm
central grounding point to the protective conductor PE (ground rail).
EWA 4NEB 812 6120-02
2
, that is as short as possible to connect the
S5-100U
3-31