Feeder Protection Of Multiple Inverters - Siemens SINAMICS G120D Operating Instructions Manual

4.2.5

Feeder protection of multiple inverters

For installations with more than one inverter, the inverters are normally powered from a 400-
V power bus with a T distributor.
Figure 4-6
Calculation of the feeder protection according to IEC and UL standards
Calculation of the feeder protection:
● Add together the rated input currents of the inverter group.
● The sum of all rated input currents must be ≤ 24 A.
● Use one of the following protection devices for the inverter group:
– Fuse or circuit breaker with a rated current of 30 A
– Intrinsically safe circuit breaker with a rated current of 25 A
The feeder protection also depends on the following conditions:
● Type of cable routing
● Limit values of the cables and system components, e.g. the T distributor.
● Country-specific regulations
If it is precluded that all of the inverters of a group operate simultaneously, it is permissible to
form larger inverter groups on one 400-V feeder. The sum of the rated input currents of all of
the inverters operated simultaneously must always be less than 24 A.
Converter with control units CU250D-2
Operating Instructions, 04/2015, FW V4.7.3, A5E34261542B AB
Power supply to an inverter group via a shared 400-V feeder
Installation
4.2 Electrical Installation
37