"AC voltage over range", is the most common kind of fault, because the voltage of the grid is not constant, it will change with the load and tide, and the output voltage of the inverter follows the grid voltage, when the grid is abnormal, the inverter needs to stop supplying power to avoid causing more damage to the grid.
The national standard stipulates that the AC output side overvoltage/undervoltage protection range is 85% to 110% of the rated voltage, and the inverter has to stop operation when this standard is exceeded. The rated voltage of single-phase grid connection is 230V, when the grid voltage is lower than 195.5V or higher than 253V, the inverter should stop in principle; the voltage of three-phase grid connection is 400V, when the grid voltage is lower than 340V or higher than 440V, the inverter should stop in principle.
1,The following two situations grid voltage will be high, one is near the step-down transformer, in order to ensure that the voltage is normal in places far from the transformer, taking into account the line voltage loss, generally will pull up the transformer output voltage; two is the user side of photovoltaic power generation can not digest, transported to a more distant place to raise the voltage, resulting in the inverter output side voltage is too high, causing the inverter protection shutdown.
When there are three ways to keep the inverter running: one is to increase the output cable diameter, because the thicker the cable, the lower the impedance; two is to move the inverter closer to the parallel network, the shorter the cable, the lower the impedance; three is to manually adjust the inverter voltage range, but can not be adjusted too high, more than 270V may damage the user other power equipment.
2,If the inverter AC line is connected wrongly, it may also cause the inverter to report "AC voltage over range" fault. If the phase line and zero line are connected wrongly, the inverter A phase will show the line voltage 380V, B, C will show the phase voltage 220V, the inverter thinks the voltage is too low and does not start. This happens in the installation stage of the inverter.
The above figure is the AC voltage over range warning reported by the inverter, and the voltage of each phase of the grid seen from the APP monitoring, among which AC1 is normal, AC2 and AC3 voltage is low, after the field test, the phase line L1 and zero line N line are reversed, the phase line L1 and zero line N line are switched, and the inverter is back to normal.
3, AC switch contact poor or damaged, will also lead to the inverter reported "AC voltage over the range" fault. After the inverter AC switch, due to long operation, if the cable is not tightened, or the switch quality is not good, the contacts will have a relatively large internal resistance, which may lead to voltage drop.
The above figure is a power station reported AC voltage out of range warning, from the APP monitoring to see the voltage of each phase of the grid, AC1 is 10.1V, AC2 is 126.2V, AC3 is 128.9V, the site measurement grid voltage is normal, the switch is not disconnected, but the switch temperature is relatively high, disassemble the cable terminals, found that the contact points become black. After renewing the cable connector and the switch, the voltage returned to normal and the inverter could operate.
