Bill, an inductive kick can generate broadband RF. The RF can then activate
the trip function in the GFI circuit. Kind of a false alarm in a way.
The kind of GFI used for hot tubs seems like it would be best for this
If you can, try changing the motor switch to a solid state relay.
Have you tried MOV's across the line?
I had a problem with a certain type of power strip. This one had a neon
indicator from hot to ground (to indicate proper wiring) it was enough to
trip out the protection built in to an inverter.
A thyristor switch could be handy. It could allow lagging inductive
current to continue to flow until zero current causes the thyristor to
become nonconducting. But what I am using is a cheap Harbor Freight
timer that allows any time on.off schedule in 15 minute combinations.
An old man would be better off never having been born.
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