Siemens SIMATIC NET PROFIBUS manual Fitting Strain Relief, Pressure, Torsion, Bending Radius

Installing LAN Cables

Fitting Strain Relief

Make sure that you provide strain relief approximately 1 m from the connection point on all cables subject to tensile force. Shield clamps are not adequate for strain relief.

Pressure

Too much pressure on the cables must also be avoided, for example crimping the cable when securing it in position.

Torsion

Torsion can lead to the elements of a cable being displaced and degrading the electrical characteristics of cables. LAN cables must not be twisted.

Do not twist trailing cables and festooned cables.

Make sure that you install the SIMATIC NET trailing cable and the SIMATIC NET festoon cable without any twisting. The line printed on the outer sheaf along the length of the cable helps to make sure that the cable in not twisted. If such moving cables are twisted during installation, the cables will probably be damaged soon after they are put into operation!

Flexible Cable for Torsional Load

If the cable is liable to be subjected to torsional load (for example robot cables), use the “SIMATIC NET” flexible cable. This cable is described in Chapter 4 “SIMATIC NET PROFIBUS Cables”.

Bending Radius

To avoid damage within the LAN cables, they must at no time be bent more sharply than the minimum bending radius.

Note the following:

SWhen pulling in cables under tensile load, much larger bending radii must be adhered to and when the cable is in its final installed position.

SBending radii for non–circular cables apply only to bending the flat, broader surface. Bends in the narrower surface require much greater radii.

The permitted bending radii of your LAN cable can be found in the technical data sheets of the LAN cables in Chapter 4.

C-22	PROFIBUS Networks SIMATIC NET
	6GK1970-5CA20-0AA1 Release 2 05/2000