SMA AUTOMATIC SWITCH BOX M-20 - Manual (Page 46)

6 Commissioning SMA Solar Technology AG
46 AS-BOX-M_L-IA-IEN110320 Installation Guide
6 Commissioning
6.1 Dimensioning the thermal fuse for loads
The dimensioning of the thermal fuse depends on the device type and the size of the fuse in the
distribution.
Selectivity of the thermal fuse:
In unfavorable constellations e.g. the same fuse value is connected twice in a row, it may be
impossible to achieve selectivity between the lead fuses to be inserted and the upstream or
downstream fuses. This is unavoidable due to the complexity of the Backup system with several
feeding sources.
Automatic Switch Box M-20
1. If the rated current of the back-up fuse in the distribution is 40 A, insert a fuse link with a rated
current of 40 A into the fuse-switch-disconnector "AS-F5".
2. If the rated current of the back-up fuse in the distribution is lower than 40 A:
– Insert a fuse link with the same rated current of the back-up fuse in the distribution into the
fuse-switch-disconnector "AS-F5".
– Set the parameter "232.02 GdCurNom" to the value of the back-up fuse via the
Sunny Backup. By doing so, you change the maximum current drawn from the grid.
3. If the rated current of the back-up fuse exceeds 40 A in the distribution:
– Insert a fuse link with a maximum rated current of 40 A into the fuse-switch-disconnector
"AS-F5".
– Insert a fuse with a maximum rated current of 40 A into the distribution.
Automatic Switch Box L-20
1. If the rated current of the back-up fuse is 63 A in the distribution, insert a fuse link with a rated
current of 63 A into the fuse-switch-disconnector "AS-F5".
2. If the rated current of the back-up fuse in the distribution is lower than 63 A:
– Insert a fuse link with the same rated current of the back-up fuse in the distribution into the
fuse-switch-disconnector "AS-F5".
– Set the parameter "232.02 GdCurNom" to the value of the back-up fuse via the
Sunny Backup. By doing so, you change the maximum current drawn from the grid.
3. If the rated current of the back-up fuse exceeds 63 A in the distribution:
– Insert a fuse link with a maximum rated current of 63 A into the fuse-switch-disconnector
"AS-F5".
– Insert a fuse with a maximum rated current of 63 A into the distribution.