Siemens SINAMICS S120 Combi Manual page 292

Cabinet design and EMC
12.6 Cable shielding and routing
Shield support
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.
Routing 24 V cables
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.
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SINAMICS S120 Combi
Manual, 11/2017, 6SL3097-4AV00-0BP7