Cabinet design and EMC 
  13.6 24 V DC supply 
SINAMICS S120 Combi 
Manual, Edition 07/2012, 6SL3097-4AV00-0BP3 
241 
Routing 24 V cables 
When routing 24 V cables, the following must also be observed: 
●  A maximum of 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 
●  Limit conductor temperature, ≤ 70 °C for operation with the rated load current 
●  Cable length max.: 
–  10 m for the 24 V supply cables 
–  30 m for signal cables without a supplementary RC circuit 
13.6  24 V DC supply 
13.6.1  General information 
The 24 V DC voltage is required to supply the 
1.  electronics of the S120 Combi and the expansion axes (Motor Modules) via the 
integrated 24 V busbar 
2.  Electronics of the SINUMERIK 828D PPU, the Sensor Modules, the Terminal Module, the 
Braking Module as well as the process voltage of its digital inputs 
3.  Load voltage of the digital outputs 
4.  Motor holding brake 
Other loads can be connected to these power supply units if they are separately protected 
from overcurrent. 
 
 
Note 
The electronic power supply has to be supplied by the user as described in the System Data 
chapter of this documentation. 
When connecting to a "DC power supply" in the sense of EN 60204-1:1997, Chapter 4.3.3, 
functional faults can occur due to the voltage interruptions that are permitted there.