Siemens SIMATIC NET PROFIBUS manual Equipotential Bonding, When do potential differences occur?

Installing LAN Cables

SWhen removing the sheath of the cable, make sure that the braid shield of the cables is not damaged.

SWhen selecting contact elements, remember that the cables for SIMATIC NET PROFIBUS have a braid shield outer diameter of approximately 6 mm.

STo allow good contact between grounding elements, tin-plated or galvanically stabilized surfaces are ideal. With galvanized surfaces, the necessary contact should be achieved using suitable screws. Painted surfaces should be avoided at the contact points.

SDo not use shield clamps/contacts for strain relief. The contact with the shielding bar could be impaired or be broken altogether.

Figure C-4 Contacting the Shield at the Point of Entry to a Closet

C.4.4 Equipotential Bonding

When do potential differences occur?

Potential differences can, for example, be caused by different power supplies. Potential differences between separate parts of the plant can be damaging for the system in the following situations:

SProgrammable controllers and peripheral devices are linked on grounded connections

SCable shields are contacted at both ends and grounded to different parts of the plant.

C-10	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000