Planning the electrical installation 35
The inverter does not require a specific transformer notation. ABB recommends using
traditional notations, such as Dy11d0, etc.
The AC side of the inverter is designed only for IT (floating) networks, do not ground the
neutral (star) point of the transformer on the inverter side or connect it to the neutral points
of other windings.
Selecting the grid disconnecting device
The inverter is equipped with a hand-operated grid disconnecting device or an AC breaker
which isolates the inverter and the solar generator from the electrical power system. The
grid disconnecting device does not isolate the AC output busbars or internal auxiliary
transformers from the electrical power system. Before you do installation and maintenance
work on the inverter, isolate the AC output cables and busbars from the electrical power
system with an AC disconnector outside the inverter, for example, an HV breaker on the
HV side of the transformer.
Refer to Ratings on page 46 and AC output connection specification on page 53 for the
correct current and voltage dimensioning for each product. If you do not know the
installation-specific short-circuit current of the grid, use the value in AC output connection
specification on page 53 for adequate short-circuit current capability of the grid
disconnecting device. The grid disconnecting devices must be lockable.
Selecting the DC input disconnecting device
As standard, the inverter has a hand-operated DC input disconnecting device. The DC
input disconnecting device does not isolate the DC input conductors or terminals of the
inverter from the input voltage. The junction boxes must have breakers for the isolation or
other suitable devices between the PV generator and inverter, for example, a separate
disconnector box.
Refer to Ratings on page 46 and DC input connection data on page 54 for the correct
current and voltage dimensioning for each product. If you do not know the installation-
specific short-circuit value for each DC-side DC input disconnecting device, refer to DC
input connection data on page 54 for adequate short-circuit current capability of the DC
input disconnecting devices. Make sure that the DC-side DC input disconnecting devices
can handle the back feed current. The DC input disconnecting devices must be lockable.
Compatibility of the solar generator and inverter
Make sure that:
• The current and voltage of the generator match the rated values of the inverter.
• The open circuit voltage of the generator does not exceed the maximum allowed DC
voltage of the inverter.
• The operating range of the generator is between the limits of the maximum power
point tracking (MPPT) function of the inverter control program.
• The grounding requirements of the generator match the inverter.
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