Siemens SINAMICS S120 - Page 508

Cabinet Design and EMC Booksize
9.3 24 V DC supply voltage
Booksize power units
508 Manual, (GH2), 06/2008, 6SL3097-2AC00-0BP6
Table 9-8 MCBs by conductor cross-section and temperature
Conductor cross-section Max. value up to 40 °C Max. value up to 55°C
1.5 mm
2
10 A 6 A
2.5 mm
2
16 A 10 A
4 mm
2
25 A 16 A
6 mm
2
32 A 20 A
24 V busbar 20 A 20 A
The trip characteristic of the MCBs must be selected to match the loads to be protected and
the max. current provided by the power supply unit in the event of a short-circuit.
Example: calculating 24 V DC current requirements
Table 9-9 Example of 24 V DC current requirements
Component Number Current consumption
[A]
Total current consumption
[A]
CU320
8 digital outputs
1
8
0.8
0.1
0.8
0.8
Active Line Module 36 kW 1 1.5 1.5
Motor Module 18 A 2 0.85 1.7
Motor Module 30 A 3 0.9 2.7
Encoders 5 0.25 1.25
Brake 5 1.1 5.5
Total: 14.25