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I need Electric Motor Help

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randyjaco

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#1
I just picked up what I think is a 5 hp single phase motor. The owner said that it came off some sort of alternator testing device. There is no nameplate on the motor or anything on it that indicates its manufacture, specifications or set up. See the pictures below. Basically, the housing is 8.5" in diameter with a 1.125" shaft. It has 2 capacitors on it, which probably need replacing, one discharging some sort of black tar-like material.
The capacitors are #4cu45 (378-454 MFD) 110/125 VAC.
It has 6 leads coming off of it.
1 red
2 red
3 red
4 red
5 white
6 White

It was hooked up (probably wrong) as follows:
1 to white 220v leg
4 to black 220v leg
5 to ground (i am sure that is wrong)
2, 3, & 6 were connected to each other.

The 4 and 5 wires go to the 2 capacitors.

In that configuration the motor hums and turns slowly

Can anyone advise me on how to get this thing running? I have already ordered the new capacitors. The six leads have me stumped. Most motors I have dealt with had 8.

TIA
Randy IMG_20181013_152102.jpg
 

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Cadillac

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#2
Were those wires burnt up before or after you ran it? If wired correctly and the motor hums usually means the start cap is shot. Give it a spin with your hand being careful of course if it comes up to speed that confirms the start cap theory. Wiring you'd have to pull out a multimeter and check windings.
 

randyjaco

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#3
The wires aren't burned. The insulation is dry-rotted. If I can get the motor running I can replace them. Hand spinning them didn't have much effect. I have ordered new caps.
 

Bi11Hudson

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#4
Pure speculation on my part, at least until I could look at the name-plate. The two capacitors sort of look like a compressor duty motor. As in high starting torque... ... That means two pole, 3450 RPM. The multitude of wires is more likely to indicate dual voltage than reversable. It may, or may not, be reversible. Depends on whether some connections are made internally.

Up front, the only thing I can say for sure is that the caps are 120 volt rating and you mentioned a 240 volt source. That alone should be an indicator that the caps are shot. It looks as though someone replaced them once already and didn't look at the supply. Or tried to wire for 240 on a fixed voltage motor.(unlikely) In any case, the black goo you spotted is the packing for the cap enclosure. Definatey a bad sign.

The first step will be to ring out the windings and determine which wire is to be paired with another. The run winding(s) will be of fixed resistance, the start windings, through the centrifugal switch, will vary. If the capacitors are intact. They may need to be seperated if the caps are damaged enough. Only when the wires are identified can you start to reason out the connections. An analogue meter is preferred for such measurements, although not absolutely required. Replacing the dry rotted wires is almost a must. Shrink sleeving may pay off here.
Bill Hudson​
 

randyjaco

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#5
Thanks for responding Bill. I sure hope it's not a non-reversible compressor motor. I do need the 3450 rpm, because I want to run a planer off it, but it needs to run clockwise. I was thinking (hoping) that the two120 volt caps would each handle one leg of the power? All of the motors I have worked on in the past only had one cap. I now have a diagram from another forum that may help with tracing the windings. I do have an analog meter. I will give it a look tomorrow.

I have had some success reversing non-reversible motors, but turning the rotor around gives some reduction in torque and I need all I can get.

Randy
 

markba633csi

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#6
Hi Randy- the 5 to ground is probably not far off, although it most likely should go to neutral; Even though the motor was wired for 240v the start circuit may be 120 volt, hence the 120 volt caps. Many dual voltage motors are that way.
Post back when you get the new caps installed
mark
ps it should be reversible if the rotation is wrong
 

JPigg55

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randyjaco

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#8
Well the caps should be in Thursday, so I did a little more investigating
All the wires have infinite resistance to the frame. (good)
1 to 2 got me 1.7 olms
3 to 4 got me 1.7 olms
5 to 6 got me 4.5 olms with capacitor leads joined together. The 2 capacitors seem to be in parrallel.

When I get the caps, I am figuring that I should do the following hook up:

CW Rotation
1 and 5 to L1
4 to L2
2,3 and 6 Joined

CCW Rotation
1 to L1
4 and 5 to L2
2,3 and 6 Joined

Does anyone see a flaw in that logic? Any other input?

Thanks
Randy
 

randyjaco

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#9
Can anyone tell me what a Pole Pig is?
 

ttabbal

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Can anyone tell me what a Pole Pig is?

I've never heard the term in machining, but from electrical groups it's the transformer on the pole. It looks like a pig with the long ears being the high voltage insulators.
 
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