The order arrived but there's no connection diagram inside. The seller sent me details by message and it was okay. I recommend the seller. I have bought many avr from shaluo. Please be warned when connecting that the terminal "V" is the power supply for the AVR whilst terminal "U" is just for voltage sensing. Terminal "N" is neutral and is connected to generator star point. In order to prevent generator over-voltage when the sensing connection is lost, I suggest to "bridge" the terminals V & U at the AVR. I hope the supplier takes note and should provide this jumper by default in next orders.