Cabinet design and EMC   
12.6 Cable shielding and routing 
  SINAMICS S120 Combi 
292  Manual, 11/2017, 6SL3097-4AV00-0BP7 
The cable shields must be connected as close to the conductor terminal connections as 
possible to ensure a low-impedance connection with cabinet ground. For power cables from 
Siemens in which the shield is connected to the connector shell (see relevant catalog), this is 
a sufficiently good shield support. 
For components that do not have any special shield connection or where the shield 
connection is not sufficient, the cable shields can be connected to the metal mounting plate 
using hose clamps and toothed rails. The cable length between the shield contact point and 
the terminals for cable cores must be kept as short as possible. 
When laying 24 V cables, the following must also be observed: 
●  No more than 1 conductor pair may be bundled together. 
●  24 V conductors must be routed separately from other cables and conductors that could 
carry the operating current. 
●  24 V cables must never be routed parallel to power cables. 
●  24 V cables as well as power cables should be routed to the components so that they 
never cover ventilation slots. 
Conditions of use for 24 V cables 
●  Ambient temperature: 55° C 
●  Conductor limit temperature: ≤ 70° C for operation with the rated load current 
Conductor limit temperature for UL applications: 60° C 
●  Maximum cable length: 30 m for 24 V power supply cables and for signal cables without 
additional circuitry  
Surge voltage protection devices must be used for longer cable lengths.