One cheap way to stop the rotation, and possibly limit damage to the coax is
to put a time limit on rotation once it starts. Let it run 15 seconds or so
before it disconnects all power. After turning more than 15 seconds (or
whatever time you prefer) the operator will need to initiate a start again
to continue, which could be just pushing a button. A little design
involved, but possibly a failsafe opening a relay to all power lines to the
rotor. While you are at it, you might put in fault detection that would
show a failure. Otherwise pushing the continue button would be a problem.
I haven't thought this out in detail yet.
Jim - KR9U
>>>A bit more info: The prop pitch uses two windings: one for CW and the
other for CCW. A common lead connects to the ends of each and ultimately,
this common lead routes to the controller's MOSFET. The M2 controller uses
a P&B frame relay that directs +48V to either the CW or CCW winding,
depending on the called direction. The relay's NC contacts are on one or
the other windings. I forgot which. But the MOV failure would result in
current in this NC winding since its connected to +48V via the NC relay
contact.
Paul, W9AC
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