ECN Forum Forums General Topics of the Trade General Discussion Area strange motor wiring

You don't get an instantaneous reverse with a 1-phase motor.

Plugging is a 3-phase phenomena.

A reversing switch in a capacitor start motor needs to re-engage the start windings and get the field in proper sequence.

So it goes Left-Stop-Right. Never Left-Right like plugging a 3-phase motor.

I will go play with this lift again when I get the chance but I think I saw this thing flip directions before it stopped. It hummed a second and went off the other way. I didn't really see it all put back together. Once we got it wired I went back to my project and let him finish it up.

Tesla,
If plugging is what I imagine as "inching", you can use that with any single phase motor, all it takes is a motor with a reduction drive and controls that have momentary switches, for things like up or down.
They also have a COD (Change of Direction) contactor, with an adjustable timer to make sure that the gearbox has stopped turning before the motor starts heading the other way.
With worm drive gears this is very important.

A 1-phase machine whose connections are flopped while running -- with the start windings no longer connected -- will treat the wave change as if the induction rotor 'slipped' and then simply keep on spinning in the same direction. This is an inertial effect.

To get a 1-phase to reverse the start windings need to be re-engaged -- hopefully after the speed drops to zero.

3-phase machines will violently reverse torque when plugged. It's an ugly thing.

About 7 years ago I connected a pair of 5 h.p. vibrator motors that need to be plugged to stop them real fast. When they shut down they coast for about 3 seconds then get 3 seconds of reverse rotation. After stopping at least once per day for that many years, it seems normal, except reverse rotation has over-sized overloads and they occasionally trip.