Sungrow SG30CX, User Manual

Page: 45 / 113

35
AC circuit breakers should be installed on the output side of the inverter and the
grid side to ensure safe disconnection from the grid.
• Determine whether an AC circuit breaker with greater overcurrent capacity is re-
quired based on actual conditions.
• Do not connect any local load between the inverter and the AC circuit breaker.
• Multiple inverters cannot share one AC circuit breaker.
Residual Current Monitoring Device
With an integrated universal current-sensitive residual current monitoring unit included, the
inverter will disconnect immediately from the mains power once a fault current with a value
exceeding the limit is detected.
However if an external residual current device (RCD) (type A is recommended) is mandatory,
the switch must be triggered at the residual current. RCD of other specifications can also be
used according to local standard. The recommended residual current is as follows.
Inverter Recommended residual current
SG30CX 330 mA
SG33CX 330 mA
SG40CX 400 mA
SG50CX 500 mA
SG30CX-NI 330 mA
SG50CX-NI 500 mA
Multiple Inverters in Parallel Connection
If multiple inverters are connected in parallel to the grid, ensure that the total number of par-
allel inverters does not exceed 30.
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.
User Manual 5 Electrical Connection