SMA SB 1100LV - Manual (Page 51)

SMA Technologie AG Rating for a line circuit breaker
Installation Guide SB1100LV-11:SE2006 Page 51
11 Rating for a line circuit breaker
Required technical information for the inverters used
• Maximum output current = 5 A
• Maximum permissible fuse protection for the inverter = 16 A
The choice of cable together with the way it is routed, ambient temperatures and other
underlying conditions limit the maximum fuse protection for the cable.
•
In our example we assume that the chosen cable (2.5 mm²) is ideally routed and
can take a nominal current of 11 A.
Selecting a line circuit breaker:
• The maximum possible nominal current for the cable used and the maximum
possible fuse protection for the inverter now limit the maximum possible nominal
current for the line circuit breaker.
• In our example, 10 A is possible.
However, the thermal suitability of the line circuit breaker still needs to be checked.
Example for the thermal rating for a line circuit breaker in a photovoltaic electrical
power unit operated in parallel with the low-voltage grid.
We assume a PV system with 9 Sunny Boy SB 1100LV inverters, with three
inverters per phase.