Siemens SIMATIC NET PROFIBUS manual Handling the Shield

Installing LAN Cables

Note

If there is a potential difference between the grounding points, an illegally high compensating current can flow through the shield grounded at both ends. To rectify the problem, do not, under any circumstances, open the shield of the LAN cable.

SInstall an additional bonding conductor parallel to the LAN cable that takes over the shield current (for notes on equipotential bonding refer to Section C.4.4)

SUse fiber-optic cable instead of electrical cable (safest solution).

Handling the Shield

Note the following points when handling the shield:

SSecure the braided shield with metal cable clamps.

SThe clamps must make good and large-area contact with the shield (see Figure C.3 ).

SContact SIMATIC NET PROFIBUS cables only using the braided copper shield and not the aluminum foil shield. The foil shield is connected to a plastic foil to increase tearing strength and is therefore non-conductive.

SContact the shield with the shielding bar directly at the point at which the cable enters the cabinet.

Figure C-3 Securing Shielded Cables with Cable Clamps and Ties (schematic representation).

PROFIBUS Networks SIMATIC NET	C-9
6GK1970-5CA20-0AA1 Release 2 05/2000