German tool grinding motor needing help

My dad has this motor that was originally wired up 220V. His friend came over and wanted to hook it up for 120. Im not sure how far he got, but he ended up passing away. I would like to get it working on 120V, and how to go about it.

Im confused because they are two identical blocks where you land wires, both have letters X, Y, Z, and U, V, W.

On the print it has Ua, Ub, Va, Vb, and Za, Zb. (The print doesnt show X and Y)

How are they coming up with what is "a" and what is "b"?

It is an eight lead motor. I will post some pictures.

Thanks guys,
James

Fascinating!

That's a fascinating setup!

James, It looks like to me... that some clever German guy came up with a combination single/three phase motor setup.

From what I see, I THINK what that diagram illustrates, is a three phase motor with it's own static-converter... meaning, you've got three legs on 120-degree intervals. ONE of the capacitors serves as a start cap, and the other APPEARS to be unused.

Typically, UVW or XYZ indicates three legs of a tri-phase setup. In this case, you only have TWO, so it's a single-phase intention.

The reference to 'bridges'... that's the metal 'shunts' between terminals.

The discrimination between Ua and Ub, etc. merely indicates ends of the legs. The way you determine if you've got 'em right, is hook it all up (guess and golly), and apply power for a short time ('jog' it), and see which way it spins. If it spins backwards, swap A for B on ONE side- this will reverse the field polarity and kick the motor off in the opposite direction.

"ONE of the capacitors serves as a start cap, and the other APPEARS to be unused"

It would be a combination start/run cap.

On 110, 20 µF is selected whereas on 220, 5.5 µF is selected.

This is correct as the capacitance required is a function of the square of the applied voltages.

220 would normally require 1/4 of the 110 capacitance.

Conversely, 110 would normally require 4 times the 220 capacitance.

But, 20/5.5 = 3.6, which is reasonably close to 4.

I would assume the designer experimented with 5 and also with 5.5, and determined that 5.5 gave the best performance on 110.

I suspect this machine, perhaps a Deckel SO or a clone of same, has a three-phase wiring diagram somewhere in its instructions manual.

grinder motor

IMHO it is a dual voltage permanant split capacitor motor. It has four coils two run and two start. As Peter says the required capacitor is voltage dependant. The bridges connect the windings in parallel for 110 Volt or in series for 220 Volt. Not three phase at all. And yes, thank you Peter for "This is correct as the capacitance required is a function of the square of the applied voltages." Did not know that. I think Ua and Va would be run winding 1, Ub and Vb would be run winding 2, Wa and Za start winding 1, Wb and Zb start winding 2. Lloyd H

Peter it does talk about 3ph wiring in the manual.

From messing with it, i believe, it has four coils. Two starting and two run.

I actually got it running, but it seems that it is not producing any torque to spin the little belt? I hooked it up two ways. One way seem to get warm, and I could smell it. The other way was when I jogged the hot from the switch and removed it, it still ran?

(I wish i had a simple program that let you build a schematic like electronic workbench) Does anyone one know of one I can use online?

Anyways,

It has two yellow wires and two black wires, along with two blue and two red. The run coil (with lower ohmic value) is one black and one yellow. So I tied both the blacks together and both yellows. Then did the same with the reds and blues. One side of the reds I have the capacitor lead to, and the other side of the (start coil) I joined with one side of the run coils along with the neutral. At the other end of the run coil i tied the hot in from the switch.

(im trying to remember this, for the motor is at my dads)


Is that right or wrong? WRONG!

manual

Perhaps the manual covers single and three phase models as well, or it could be info to connect the single phase grinder to a three phase feed using two legs.