Re: Strange lost step problem, grounding related

The earlier note about changing the inverter frequency from 50 to 60 Hz
is probably another hint. While grounding is most certainly the problem,
the stepping trouble was much worse at 50. Presumably, the inverter
is still "bucking" the 60Hz line current present in your weird ground
loop(s). If the neutral side of the inverter could be electrically bonded
to the neut side of the line, or possibly to "ground", the problem might
vanish. I'd be inclined to check the inverter to look at the relationship
between L,N and G, however <grin> /mark