Siemens Sinamics S120 Manual page 105

NOTICE
Damage to other loads as a result of overvoltage
Overvoltages of switched inductances (contactors, relays) can damage connected loads.
• Install suitable overvoltage protection circuits and devices.
Note
Malfunction because 24 V supply voltage is too low
If the 24 V supply voltage falls below the specified minimum value on a device in the
assembly, a malfunction can occur.
• Select an input voltage that is high enough for there to be sufficient voltage at the last
device. Do not exceed the maximum value for the supply voltage. If required, supply the
voltage to the assembly at various locations in the lineup.
Note
A regulated DC power supply is required to operate motors with a built-in holding brake. The
voltage is supplied via the internal 24 V busbars. The voltage tolerances of the motor holding
brakes (24 V ±10 %) and the voltage drops along the connecting cables must be taken into
account.
The DC power supply should be set to 26 V. The Control Supply Module supplies 26 V. This
ensures that the supply voltage for the brake remains within the permissible range when the
following conditions are fulfilled:
• Siemens three-phase motors must be used
• Siemens MOTION-CONNECT power cables are used
• Motor cable lengths, max. 100 m
For further information about conductor protection and the possible functions of the 24 V
supply, please refer to the SINAMICS S120 Manual "Booksize Power Units" (GH2).
Power Units in Booksize C/D-Type Format
Manual, 01/2017, 6SL3097-4AC20-0BP1
6.7 Possible functions of the 24 V supply
Cabinet design
105