ABB UNO-DM-3.3-TL-PLUS Product Manual page 105

The inverter is powered SOLELY by the voltage generated by the photovoltaic generator: the
presence of grid voltage alone is NOT SUFFICIENT for the inverter to switch on.
• With the inverter in the "Missing Grid" status, close the AC switch down-
stream of the inverter thus applying the grid voltage to the inverter: the
inverter checks the grid voltage, measures the insulation resistance of
the photovoltaic field with respect to ground and performs other auto-dia-
gnostic checks. During the preliminary checks on the parallel connection
with the grid, the "Power" LED keeps flashing, the "Alarm" and "GFI" LEDs
are off.
• During the check on the grid voltage and the measurement of the in-
sulation resistance, the voltage, grid frequency and insulation resistance
values measured by the inverter are displayed. The inverter ONLY cre-
ates a parallel connection with the grid if the grid and insulation resist-
ance parameters fall within the ranges foreseen by current regulations.
• If the outcome of the preliminary checks on the grid parallel is positive,
the inverter connects to the grid and starts to export power to the grid.
The "Power" LED remains fixed on while the "Alarm" and "GFI" LEDs are
off.
To address any problems that may occur during the initial stages of operation of the system
and to ensure the inverter remains fully functional, you are advised to check for any firmware
updates in the download area of the website www.abb.com/solarinverters or at https://regi-
stration.abbsolarinverters.com (instructions for registering on the website and updating the
firmware are given in this manual).
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7 - Operation