Installation
4.2 Electrical Installation
Converter with control units CU250D-2
Operating Instructions, 04/2015, FW V4.7.3, A5E34261542B AB
37
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
Power supply to an inverter group via a shared 400-V feeder
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.