Old single phase motor hookup?

[WobblyHand]

I have a GE single phase 1/20 HP motor. 5KH23AC184. It has a right angle reduction on it. Ohmed it out and wrote down the results.
T1 and T3 are one winding and T2 + T4 is the other winding. Both measure about 12.5 ohms, although T1-T3 is slightly less at 12.3 ohms.
The windings are isolated from each other and the case.

Tried wiring it up as following.

C1 is 1.5uF 450V. Maybe have misinterpreted the name plate. It looks like it is 1.5A, not 1.5uF. The value on the plate is blank.

Originally, when I opened the lube fill port for the gear reduction there was some congealed lubricant - more like grease really. No liquid lubricant. I filled it with gear oil. I think this unit hadn't seen lube in 70 years...

The motor hums but does not turn. There is no external motor shaft for me to give it a kick start. I unplugged it after 5 seconds. Nothing was warm, there was no smoke. Did I wire this correctly? Is my value for C1 wrong?

Removed the "brush" end off the motor to inspect it. With the back end off, the shaft turns freely and the gear reduction turns. I was worried about the reduction gearing, but it seems to turn ok.

Anyone got an idea on how to get this motor to run? Can't seem to find any info on this motor.

 

[silence dogood]

For that size motor, the cap value sounds about right. However, being that old the cap most likely needs to be replace. Were you able to check the bearings too? The grease or oil could be just as bad as the gear oil.

 

[WobblyHand]

Cap is brand new, and tests ok. (Actually measured 1.5uF on a capacitance meter.) When I removed the back of the motor, I removed the shaft from the back bearing. I was able to easily turn the shaft and see the gear head reduction shaft turn. It could be that the back bearing is no good. Unfortunately, one cannot turn the motor from the output of the gear reduction. Guess it is a property of the worm drive.

Found a clue. On the side of the motor one can see some internal fan blades.

If one gives that a push (with a wooden stick) the shaft will rotate. It takes some torque to move, but it does move. If the blades are given a push when the motor is on, the motor runs smoothly and the gear head moves. Hooray! But it is not self starting. Does that mean the value of capacitance is too low? Slowly getting there...

 

[silence dogood]

Does this motor have some kind of centrifugal start switch? It should be close when the motor is not running.

 

[WobblyHand]

Not that I can tell. Definitely don't hear a switch opening or closing. Since this is only a 1/20 HP motor, it just might have the capacitor in place all the time. From what I can tell, cap sizing is a dark art, which depends on the load. Since there's a gear reduction set attached, maybe it needs a little more capacitance to start? Not keen at just throwing caps at it, but doesn't seem like I have that many options.

 

[CluelessNewB]

I'm about 99.9% sure that the 1.5 is amps not the value for a capacitor.

 

[CluelessNewB]

Type KH motors are split phase, I don't think they even use any capacitor. The type KC motors were capacitor start.

 

[WobblyHand]

I'd agree. Basically have no idea what capacitance to use. I'm getting 4.5uF and 6uF. I have 1.5uF now. That would give me 1.5, 4.5, 6.0, 7.5, 10.5, or 12uF combinations, if in parallel. Thinking out loud...

Computing the reactance we get Xc = 1/(2*pi*60*C) = [1768, 589, 442, 353, 252, 221] ohms
So the current in the coil is I = E/Xc = 115 volts/Xc = 65 mA, 195 mA, 260 mA, 325 mA, 455 mA, 520 mA

Guessing that 65mA has nowhere enough field strength to get things to turn. Right answer is a bit higher. Total current for motor is rated at 500mA. So that kind of bounds the problem, I'd guess.

 

[WobblyHand]

Type KH motors are split phase, I don't think they even use any capacitor. The type KC motors were capacitor start.

So how do you wire a split phase?

 

[CluelessNewB]

So how do you wire a split phase?

Typically the two windings are wired in parallel. Swapping the relationship of the two windings should change directions.

T1-T2-Line1
T3-T4-Line2

if direction is wrong swap T2 & T4.