SMA SSM8-21-BS - Manual (Page 14)

4 Product Description SMA Solar Technology AG
14 SSMxx-21-IA-BS-JP-en-20 Installation Manual
4.3 DC Load-Break Switch
The Sunny String-Monitor can be disconnected on the inverter side by means of a DC load-break switch. Use of the DC
load-break switch is only permissible if LV/HRC fuses with gPV characteristic are installed upstream in the inverter or the
main DC distribution box.
If a string fails, the current difference in the above example is 4.5 A which equates to a deviation of 90% from the mean
value. Assuming that the settings in the above example remain unaltered, i.e. tolerance at 10% and tripping time at
10 minutes, the error sum of 20% will already be reached after the first query interval of 5 minutes. The data logger
now issues an SMU warning.