Siemens SINAMICS S120 Device Manual page 239

Auxiliary Power Supply Modules supply power to the auxiliary power supply system of the
SINAMICS S120 Cabinet Modules as well as to other external loads. The fans of the
SINAMICS S120 devices installed in the Cabinet Modules are some of the devices
connected to this auxiliary power supply system. In addition, the auxiliary power supply
system supplies the electronics modules with external 24 VDC. This voltage is required
when the DC link is not charged, for example, to maintain PROFIBUS/PROFINET
communication.
The 230 V AC power supply can also be fed in externally via an uninterruptible power supply
(UPS) and terminal -X46.
Note
Voltage infeed
The same rated voltage must be fed into the line supply of the auxiliary power supply module
as for the connected Cabinet Modules, as the voltage fed into the auxiliary power supply
module supplies the entire system with auxiliary voltage via the auxiliary power supply
system.
If a different voltage than that of the connected Cabinet Modules is fed in, there is a risk of
an insufficient energy supply to the device fans or too high a voltage, which can cause
damage to the system.
Cabinet Modules NEMA
Manual, 04/2014, A5E03586450A
Cabinet Modules
5.7 Auxiliary Power Supply Modules
239