Siemens SIMATIC ET 200AL, System Manual

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Interference-free cable routing
3.6 Bending radii and tensile strength of cables
Designing interference-free controllers
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Function Manual, 06/2014, A5E03461486-AB
3.6 Bending radii and tensile strength of cables
Tensile strain
A high strain on the cables due to tensile forces leads to conductor material flow. The tensile
forces thus cause a change in the structure of the material and lower the conductor cross-
section. This decrease of the conductor cross-section leads, in turn, to a heating of the
conductor and premature wear of the conductor insulation.
Use the supplied cable ties to relieve the terminal points on the plugs for the I/O modules of
the product series SIMATIC S7-1500 and SIMATIC ET 200MP.
Bending radius
If you select too small bending radii when laying cables, this will cause the materials to
stretch and compress and changes the mechanical structure of the cables. The electrical
properties are impaired as a result.
Pay particular attention to the bending radii of fiber-optic cables. If the bending radii are too
small, the optical properties of the fiber-optic cable are adversely affected. Reliable
transmission is no longer guaranteed.