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The inverter has not been tested to AS/NZS 4777.2:2020 for multiple inverter combinations.
MV Transformer
The MV transformer used together with the inverter should meet the following requirements:
• A distribution transformer can be used if it is designed for the typical cyclical loads of a
PV system (there is load in the day and no load at night).
• A liquid-immersed type transformer or a dry type transformer can be used, and the shield
winding is not a requisite.
• The line-to-line voltage on the LV side of the transformer should endure the output volt-
age of inverter. When the transformer is connected to the IT grid, to-ground withstanding
voltage of the LV winding of the transformer, the LV side AC cables, and the LV side sec-
ondary equipment (including the relay protection device, detection & measuring device,
and other related auxiliary devices) should not be lower than 1,100V.
• The line-to-line voltage on the HV side of the transformer should comply with the local
power grid voltage.
• A transformer with a tap changer on the HV side is recommended in order to keep the
voltage consistent with the grid voltage.
• At an ambient temperature of 45℃, the transformer can run in 1.1 times of load for long
time.
• A transformer with a short-circuit impedance 6% (permissible tolerance: ±10%) is
recommended.
• The voltage drop of system cable is no more than 3%.
• The DC component that the transformer can withstand is 1% of the fundamental current
at rated power.
• For thermal rating, the load curve of the transformer and environment conditions should
be taken into account.
• The apparent power of the inverter should never exceed the power of the transformer.
The maximum AC current of all inverters connected in parallel must be taken into ac-
count. It is recommended that the total number of inverters that are connected to the grid
not exceed 30.
• The transformer must be protected against overloading and short circuit.
• The transformer is an important part of grid-connected PV generation system. The fault
tolerance capacity of the transformer should be taken into account at all times. The fault
include: system short circuit, grounding fault, voltage drop, etc.
• Take ambient temperature, relative humidity, altitude, air quality, and other environmental
conditions into account when selecting and installing the transformer.
5.6.2 Requirements for OT/DT Terminal
OT/DT terminals (not included in the delivery scope) are required for fixing AC cables to the
terminal block. Purchase the OT/DT terminals according to the following requirements.
• Specification: M8;
User Manual 5 Electrical Connection
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