Limit function user manual for US split phase AC grid

Limit function user manual for US split phase AC grid

Limit function user manual for US split phase AC grid.

First connecting method for SUN-2000G2(Suggested)

The inverter should be connected to compensate 240V loads. Because the inverter will produce same value feed current at L1 and L2, and 240V loads also consume same value current at L1 and L2, so with the limit function of the inverter, the inverter will just produce power that is same as or less than 240V loads’ power, there will be no extra countercurrent feeding to the AC grid.

So if the 240V loads were connected at separate lines and not mixed with 120V loads, you can connect the inverter and limit sensor as picture1.

Picture 1 Connecting method for Compensating 240V loads’ power at individual live lines

Second connecting method for SUN-2000G2(Suggested)

If 240V loads and 120V loads were connected at same live lines, but 240V loads were connected after 120V loads, the best connecting method is connecting the inverter just before 240V loads and after 120V loads, and the limit sensor should clamp one live line at the position after the 120V loads and before the inverter.
See picture 2.

Picture 2 Connecting method for Compensating 240V loads

Because the inverter will produce same value feed current at L1 and L2, and 240V loads also consume same value current at L1 and L2, so with the limit function of the inverter, the inverter will just produce power that is same as or less than 240V loads’ power, there will be no extra countercurrent feeding to the AC grid.

Third connecting method for SUN-2000G2(Can be used, but not suggested)

If 120V loads and 240V loads were mixed, and the 240V loads were connected before 120V loads, the inverter and limit sensor can be installed as picture 3.

Picture 3 Connecting method for Compensating mixed loads

With this connecting method, because the total loads’ consumption at L1 and at L2 will not be same, but the inverter will just produce same value feed current at L1 and L2, so the limit sensor must clamp at the L1 or L2 which total loads’ power is smaller, this will prevent extra countercurrent feeding to the AC grid, otherwise, there will be extra countercurrent feeding to the AC grid if the inverter can produce enough current to compensate the larger current at L1 or L2. If you connect system like picture 3, loads’ power at L1 must be less than loads’ power at L2, otherwise, the limit sensor should clamp at L2.

Using two SUN-1000G2 inverters to connect with US split phase AC grid(Good solution)

Picture 4: Connecting method for two SUN-1000G2 units

Using two SUN-1000G2 inverters to compensate L1 and L2 loads’ current individually, with this method, the limit function of the inverters can work very well, there will be no extra countercurrent feeding to the AC grid from L1 and L2. You also can just connect one SUN-1000G2 unit with a limit sensor at one of live lines.

Important information:

After Having connected the inveter and limit sensor as one method listed above, If you want to use limit function, you also need to do below configuration on LCD display, You should select “Limit Mode” and “Internal Limiter” as picture 5.

Picture 5: Limit mode configuration

If the display shows as picture 6, this means the limit sensor is not connected well or there are no loads powered on, you can check the limit sensor and switch on some loads. If there is no loads’ power, the inverter will not produce power under limit model.

Picture 6: Zero AC grid power

If the display shows as picture 7, the AC grid power is negative, this means the clamping orientation of limit sensor is wrong.

Picture 7: Negative AC grid power

If so, you need to clamp the limit sensor to opposite direction as picture 8.

Picture 8: Correcting the orientation
If you did every thing correctly, the LCD display should show as picture 9.

The inverter just produces almost same power as the loads’ power, so the AC grid just consumes very small power if the inverter can produce enough power to compensate the loads’ power.
(Remark: Numbers on the LCD display will be different for different inverter and different using environment.)

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