7
EN
Transition from
feeding energy
into the grid to
emergency power
mode
1.
The public grid is monitored by the inverter's internal grid and system protection unit
and by the Fronius Smart Meter connected to it.
2.
Failure of the public grid
3.
The inverter carries out the necessary measures according to the country standard
and then switches off.
Contactors K1 and K2 drop out. This disconnects the emergency 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 3-pin open. The inverter activates relay K3,
which interrupts the supply to contactors K1 and K2. This prevents unintentional acti-
vation of contactors K1 and K2 and thus a grid connection when voltage is restored in
the grid. The NC auxiliary contacts of contactors K1 and K2 send feedback to the in-
verter that the contactors are open (a condition for starting the emergency power
mode).
4.
The NO contact of relay K3 gives optional feedback to the inverter on whether the lock-
ing was successfully performed by relay K3.
5.
The inverter decides based on both the relay's feedback as well as the measurement
that the emergency power mode can be activated.
6.
The inverter starts emergency power mode after a defined checking period
7.
All loads in the emergency power circuits are supplied with power. The remaining
loads are not supplied with power and are safely isolated.
Transition from
emergency power
mode to feeding
energy into the
grid
1.
The inverter is operating in emergency power mode. The contactors K1 and K2 to the
public grid are open.
2.
Public grid available again
3.
The Fronius Smart Meter monitors the grid parameters on the public grid and passes
this information to the inverter.
4.
After a defined measuring period, the restored public grid is deemed to be stable.
5.
The inverter ends emergency power mode and disconnects the outputs.
6.
The inverter deactivates K3. The contactors K1 and K2 are reactivated.
7.
All circuits are reconnected to the public grid and are supplied by the grid. The inverter,
therefore, does not feed anything into the grid.
8.
The inverter can start feeding energy into the grid again after performing the grid
checks required by the country standard.
