My EG4 6500EX Exploded on restart!!!!!

[740GLE]

99.99% of the time anything happens to grid, it is collapse. Rarely if every does it go open circuit. Even if your utility pole transformer blows its HV primary side fuse from a critter getting across the HV insulator on top of pole transformer you usually share the secondary side of pole transformer with neighbors that will drag your grid down.

When grid collapses there is a momentary overload on inverter and in less than 4 milli-secs the inverter immediately releases pass-through relay. Grid collapse is usually not an instant voltage drop to zero and severity of voltage drop off rate depends on where in the sinewave cycle it drops.

Grid glitches are hard on the pass-through relay contacts though.

Routine faults are typically caused by a branch or tree coming in contact with primary voltage dropping to near zero (fault current traveling back on the neutral), not quite voltage collapse as the source (upstream of the fault) still has plenty of inertia and ability to provide fault current.

Voltage collapse is system wide loss of generation ability to control voltage and reactive needs, thankfully tree branches cause way more havoc day to day than voltage collapse.