Fronius Symo GEN24 10.0, Operating Instructions Manual, Page: 39 / 120

All-pin split separation cabling variant (Italy)
Functions - Measuring and transferring the required parameters for energy management and
Solar.web by the Fronius Smart Meter.
- Monitoring of the voltage and frequency grid parameters by the inverter.
- Disconnecting from the public grid to enable operation in backup power mode if the
grid parameters are outside the country-specific standards.
- Reconnecting to the public grid when the grid parameters are within the limits spe-
cified by the country-specific standards.
- Establishing a correct ground connection for backup power mode.
- Option of having a separate backup power circuit or several backup power circuits
that are supplied even during failure of the public grid. The total load of the backup
power circuits must not exceed the nominal output of the inverter. Furthermore, the
performance of the connected battery must also be considered.
Transitioning
from feeding
energy into the
grid to backup
power mode 1. The public grid is monitored by the inverter's internal grid and system protection unit
and by an external grid and system protection unit.
2. Failure of the public grid
3. The inverter carries out the measures necessary according to the country standard
and then switches off.
4. The external grid and system protection unit opens contactors K1 and K2 for grid
monitoring. This disconnects the backup power circuits and the inverter from the rest
of the home network and from the public grid, as the main contacts of the contactors
K1 and K2 open at all pins. To ensure that the public grid has definitely been discon-
nected, the NC auxiliary contacts of contactor K1 give feedback to the external grid
and system protection unit.
5. The NC main contact of contactors K4 and K5 is closed, establishing a connection
between the neutral conductor and the ground conductor. The two other NC main
contacts of contactors K4 and K5 give feedback to the inverter that the ground con-
nection has been established correctly.
6. The inverter activates relay K3, which activates the remote input of the external grid
and system protection unit via an NC contact. This prevents a connection to the pub-
lic grid when voltage is restored in the grid.
7. The NO contact of relay K3 gives additional feedback to the inverter on whether the
locking was successfully performed by relay K3.
8. The inverter decides based on the contactors' feedback as well as the measurement
on the inverter terminals and the Smart Meter that backup power mode can be star-
ted.
9. The inverter starts backup power mode after a defined checking period.
10. All loads in the backup power circuits are supplied with power. The remaining loads
are not supplied with power and are safely isolated.
39
EN