FAQ

Analysis:

The DC component of the output three-phase current exceeds the software setting value.

Solutions:

1) Power off both the DC and AC sides, wait 10 minutes and power on again to confirm whether the fault disappears.

2) If the fault still exists, provide the inverter serial number, Sineng team will update the inverter to the latest.

3) If the fault cannot be recovered after updating, there should be something abnormal inside the inverter, the inverter needs to be replaced.

Analysis:

The inverter detects the voltage of PV+ to ground and PV- to ground, and calculates the resistance of PV+ and PV- to ground respectively. If the resistance on either side is lower than 33K ohms, the inverter will stop working and report this fault.

Solutions:

1) In rainy and snowy weather, the insulation performance of components to the ground will decrease. If it is an accidental phenomenon, it will have little impact on the operation of the power station.The inverter can self-recover and connect to the grid.

2) If the fault persists, use a megger or multimeter to measure the impedance of each PV+ and PV- to the ground. The measured impedance cannot be lower than 33K ohms (if the impedance is between 33K-40K, the fault may also be reported).After locating the abnormal string, check whether the PV cables are broken or squeezed, and whether the components are well grounded.

3) If the measured impedance of PV+/- to ground is normal, first power off both the DC and AC sides, then re-plug the DC and AC terminals to ensure that the terminals are tightened.

Analysis:

No voltage is detected on the AC side and the inverter is not connected to the grid.

Solutions:

1) Check whether the AC circuit breaker in the AC distribution box is on.

2) There is a power outage in the local power grid. After the AC power supply is restored, the inverter will automatically recover and connect to the grid.

3) If there's no power outage and the AC circuit breaker trips and cannot be put on, check the rated current of the breaker that trips, then check the user manual of corresponding inverter model and find the AC circuit breaker selection(in the chapter 3 of user manual), if the rated current of the breaker is not large enough, change to one with larger rated current.

4) If the AC circuit breaker has a residual current detection function(means leakage current detection), check the specification of the residual current protecion, then check the user manual of corresponding inverter model and find the recommended specifications of RCCB (residual current circuit breaker), it can be seen in the chapter 3 of user manual.If it's not large enough, adjust the residual current protection value or change to one with a larger residual current protection value if this parameter cannot be adjusted.        

Analysis:

1. The grid frequency is lower than the grid under-frequency protection point in the grid parameters.

2. The grid frequency is higher than the grid over-frequency protection point in the grid parameters.
   

   
   

Solutions:

1）The grid frequency fluctuates.After the grid frequency returns to normal, the inverter will automatically resume grid connection.

2）If the fault occurs frequently, provide the serial number of the inverter, Sineng team will check the grid overfrequency/underfrequency protection values for all 5 levels, as well as the overfrequency/underfrequency reconnection values and other parameters. Sineng team will adjust the parameters above according to specific situations.                

Analysis:

1. The grid voltage is lower than the grid undervoltage protection point in the grid parameters.

2. The grid voltage is higher than the grid uppervoltage protection point in the grid parameters.

Solutions:

1) Check whether the AC terminals are locked tightly. If not, power off both the DC and AC side, wait 10  minutes, then reconnect the AC terminals and check again.

2）The grid voltage fluctuates.After the grid voltage returns to normal, the inverter will automatically resume grid connection.

3) If the fault occurs frequently, provide the serial number of the inverter. Sineng team will check the 1st-level overvoltage/undervoltage protection value, the ten minutes over voltage protection value, the overvoltage/undervoltage reconnection value and some other parameters.Sineng team will adjust the parameters above according to specific situations.

4) If the grid voltage is between the first-level undervoltage protection point and the first-level overvoltage protection point of the rated voltage, check whether the AC cable connecting screws are tightened, especially for  SN3.0-25PT that use AC quick-plug terminals.                   

Analysis:

1. Reasons for grid adaptability 

2. This fault actually exists in the inverter

Solutions:

1) Bus overvoltage may occur during inverter operation. If it occurs occasionally, it is normal.

2) If the fault persists, use a multimeter to check whether the PV voltage of each PV array is higher than or very close to 1000V. If so, reduce the number of PV panels according to the voltage you measured. In order to ensure efficient and stable operation of the system, it is recommended that the PV open circuit voltage be lower than 950V.

3) If the PV voltage measured is between 900-950V, provide the datasheet of your PV panel, Sineng team will decide whether you need to reduce 1 PV panel for the string whose voltage is between 900-950V(because PV panels have a negative temperature coefficient).

4) If the PV volatge measured is below 900V for all the PV strings, but the fault cannot be recovered, provide the inverter serial number, Sineng team will update the inverter to the latest, if the fault is still there after updating, the inverter needs to be replaced.                          

Analysis:

The voltage between the AC side neutral line and the ground wire exceeds 30V, which is caused by leakage of the ground wire of the client's AC distribution box, generally, it's not related to the inverter.

Solutions:

1) Open the AC terminal box of the inverter, use a multimeter to measure three groups of phase voltage and line voltage on the inverter AC terminal, also measure the voltage between L1 and PE, L2 and PE, L3 and PE, and measure the voltage between N(Neutral) and PE.   

2) Provide the inverter serial number and pictures or videos about the measurements above, Sineng team will decide whether to disable the NPE voltage detection or guide you to correct the wiring mistakes.