Aha the $64k question.
Somewhat simplified: It has to do with the counter electromotive force generated by rotating machinery, ( motors can act as generators, though not very good at it) which limits the current in the windings
When running slow, less counter EMF is generated allowing much more current through the windings, plus the slower speed gives less cooling, ergo mucho heat, cooked wires.
Cooked wires(windings) let the magic smoke out of the motor and it dies.
As to how I learned? I was born curious, at age 6 already graduated to dis-assembling much my brother's motorcycle, this after pulling the film out of his Leica (pictures he traveled days to take) to look at the pictures. These acts nearly caused my demise at his hands, mother intervened, so I got to live.
In time after destroying many things I learned how they worked, eventually learned how to re-assemble.
Discovered electricity by dismantling the family radio, wanted to know what made the magic eye tuning indicator work. In the process the still charged filter capacitors discharged through my fingers, getting my attention.
This act nearly got my mother to finish me off, (radios cost 2 to 3 months vages back then, if you could get them at all) brother intervened, got live again. They recounted these things later in my adult life.
From there a lifetime of learning ensued, and still in the process. Formal education in the electric arena was as an electrician student back in the old country.
I still love to tinker, learn, and play with all sorts of gizmo's. But a lot of what I know is fast becoming obsolete.
Now in retrospect if I directed those energies to money making, I'd prolly be far richer, but not likely happier. Who knows?
