Siemens SIMATIC NET PROFIBUS manual Special Noise Suppression Measures, Underground Cabling

Installing LAN Cables

Underground Cabling

Note

Only the SIMATIC NET PROFIBUS underground cable is suitable for direct installation underground.

If the LAN cables are installed directly in the earth, we recommend the following:

Sinstall the LAN cable in a trench.

SInstall the LAN cable approximately 60 cm below the surface of the ground.

SMechanical protection should be provided for the LAN cables and a cable warning band should also be included.

SThe equipotential bonding between the buildings being connected should be installed approximately 20 cm above the LAN cables (for example a tin–plated strip conductor), The strip conductor also provides protection against direct lightening strikes.

SWhen installing LAN cables along with other cable, the clearances specified in section C.5.1 must be adhered to (for example using bricks to maintain clearance).

SThe clearance to power cables should be ≥ 100 cm unless other regulations require a greater clearance.

C.5.5 Special Noise Suppression Measures

Connecting Switched Inductances to Suppressors

Some inductive switching devices (for example relays) create interference voltages that are a multiple of the switched operating voltage. The distributed ET200 system manuals /9/ contain suggestions about how to limit the interference voltages caused by inductance by connecting them to suppressors.

Power Supply for Programming Devices

It is advisable to include a power socket for programming devices in each cabinet. The socket must be supplied by the same system to which the PE conductor for the cabinet is connected.

C-18	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000