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

I am not sure what the instant reverse switch is all about but my guess is it drops out as soon as power drops so you don't have to wait until a centrifugal switch drops.
On my lift with the normal motor, reversing it doesn't do anything until you hear the switch drop out.

Greg,
Actually what I'm seeing there with your diagram is a capacitor start motor, the capacitor feeds the start winding, until such time as the centrifugal switch opens at 70-75% Full load speed.
After that, the two run windings do the work.

Oddly enough, what voltage is this motor?
With it having a lift on it, you'd think there'd be some sort of a gear-box attached to the shaft of the motor.
First thing I would do before installing a new motor is strip down the gearbox and make sure everything inside is sound.

With respect to the relay box, it sounds to me like they needed to cascade relays, instead of installing a contactor.
This is often done to carry the switching current in forward/reverse situations.
It is the poor mans solution.

Mike, the "gearbox" is one pinion gear about 4-5 cm, driving a big ring gear maybe 30cm and the pinion gear is belt driven off the motor with a similar reduction so there is not much to inspect.

I agree the control box is probably not what I would make but it does seem to work. The one I have runs off a garden variety drum switch.

His lift is 240v, mine is the same lift tapped for 120v.
He has 2 lift plates, I just have one. I never planned on being able to afford that big a boat
It also lets me share the circuit with the lights and a receptacle on the dock. I imagine you could run 2 3/4 HP motors on 120v 20a tho.

Looks like some type of Plugging Control, or

-- Scott

The effect is if you flip the motor into reverse, it reverses, instead of keeping going the same way.
Evidently it is not a centrifugal switch.

The way the "Instant Reverse Switch" is shown in the Schematic, along with the Positioning in the Auxiliary Circuit, should be for Plugging the Motor.

***FYI***

For those unfamiliar with the term -Plugging-:

"Plugging" is a Motor Control term for rapidly stopping the Motor by Temporarily Reversing the Rotor's direction.
This is achieved by momentarily connecting the Motor, so as to run in the opposite direction - resulting in a very rapid stall.

"Anti-Plugging" Control would be used to stop the Motor "Normally", then automatically start in the reverse direction.

-- Scott

Thanks Scott, that was a new one for me.
I have seen schemes that shunted the windings of a motor to stop it faster, usually with mechanically interlocked relays.

Plugging is normally associated with Life Safety events.

It's brutal on the windings -- so much so that the typical motor can be ruined by its first plugging event.

However if plugging will stop a train from plowing into another... so be it.

A collision will surely ruin all.