UNB-BUS happens when voltage of DC BUS is not equal to two times of the voltage of DC half-BUS .
1. Please restart the inverter . If this happens again, please move to the next step;
if the inverter back to normal, then case is over;
2. If this happens to a newly installed inverter, please recheck voltages of all the DC input strings . If they are higher than the required value in the data sheet, please remove some PV panels and try again.
3. If this happens to a normally working inverter that has been working for days or months or years, please contact after-sales people of Ginlong.
4 Use a multi-meter to check the voltages between PV+ and earth, PV- and earth of all of the PV strings. (it should be decreasing from a certain value between 5% of Voc and 95% of Voc);
If the voltage value shown on the multi-meter is constant, than there must be something wrong in this PV strings.
5 Please check the value of V_BUS and H_V_BUS in Running messages of Advanced info in the LCD of the inverter.
At the same time , you need to send all the data that you have got to Ginlong, and the model as well as its serial number too, thanks.
