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I'll try.
Slip as you are using it applies to DC motors, if I understand correctly.
When an AC motor is overdriven it turns into a generator. There are no major differences from an AC generator and motor.
Good test:
Find a fan around 30-50HP
Turn the contactor off.
During the 2 min or so it coasts down, put your meter on the bottom leads of the contactor. There will be voltage present. This is why (before VFDs were reasonably priced) you always had to wire a delay relay into the control circuits. If you closed the contactor while it was spooling down, BOOM, blown fuses and sometimes the whole contactor.
This is the way VFDs working in "common bus" configuration work.
Example:
A conveyor bringing large ore down hill to a crusher spins its motor through gravity.
That is fed to the common DC bus of its VFD to the bus of other VFDs that send the crushed ore to the top of a pile, or into rail cars
Make sense ?
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