Analysis: Grid frequency too low
1. Check what the displayed AC frequency value is, check if the value is in the rated range.
2. Check if AC terminal and distribution box internal connection is correct, check if any connection is loose or disconnected, check if the breaker in distribution box was tripped.
3. Use a multimeter to see if the grid wire connection is correct ; check if the grid frequency is too low
4. Check if the inverter’s safety code be set correctly and Grid under-frequency point be set to match actual situation.
5. Please Wait for a while until the grid frequency recovered, then check if the inverter can return to normal