Cable Shields

• Use only shielded data cables. The shield should be earthed at both ends.

  A cable shield only earthed at one end can only protect from capacitively coupled interference and low-frequency disturbances (50 Hz hum).

• Avoid parasitic currents flowing through the cable shields.

  This can be done by installing current-carrying equipotential bondings.

• Use only cables with braided shields.

  Foil shields are not robust enough, cannot be contacted well and have poor HF properties.

• Use only metallic or metal-plated plugs for shielded data cables.

• Use only shielded cables for analog signals.

  For small signals earth the shield only at one end.

• Earth the cable shield directly with a clip when entering the switch-gear cabinet.

  Do not cut the shield until the cable reaches the module connected.

Note

The connection between the PE bar and the shield bar must have a low impedance.