[4]

I need some Electric Motor Help Please

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

randyjaco

Active User
H-M Supporter - Gold Member ($25)
Joined
Oct 5, 2010
Messages
801
Likes
311
#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.
In the end, I need this motor to turn Clockwise.

TIA
Randy View attachment 277579
 

wa5cab

Downloads Moderator
Staff member
H-M Platinum Supporter ($50)
Joined
Dec 25, 2011
Messages
4,271
Likes
1,029
#2
Randy,

First, in a US standard 120/240 circuit hook up, the Neutral is grounded at the pole and the wire coming from it to your meter and from the breaker panel to the loads should be White. One of the 120 lines should be Black and the other Red if the circuit is going to run a 240 VAC load.

My first assumption would be that the four Red leads coming out of the motor go to the two RUN windings and that the two White leads go to the START circuit. And I assume that by Ground, you mean the actual safety ground (usually either Green or Bare) and not the Neutral. Assuming that all of that is correct or true, the presence of two RUN windings implies that the motor can be wired for either 120 or 240 volt operation. The START winding in such a motor is only good for 120 VAC. So in order to hook up the motor, you are going to have to have three instead of two insulated wires.

Before going any farther, with an analog multimeter, disconnect the six wires and confirm that you have continuity but not zero ohms from 1 to 2 and from 3 to 4, and that the two resistance readings are about the same. Check (after you replace both capacitors) that from 5 to 6, the ohmmeter needle jumps up and rapidly falls back to infinity. And that measuring from ground to any one of the six wires reads infinity.

If all of that checks out, and calling the Neutral White, one 120 volt line Black and the other one Red (Red to Black should be 240 VAC and from either one to White should be 120 VAC), and ignoring any switches, connect 1 to Red, 2 to 3 to 6 to White, and 4 to 5 to Black. That should run. If it runs backwards, swap 5 and 6, or move 5 to Red.

The reason (or at least one reason) that the motor wouldn't start was that there was no voltage on the start winding.
 

randyjaco

Active User
H-M Supporter - Gold Member ($25)
Joined
Oct 5, 2010
Messages
801
Likes
311
#3
Thanks for the reply.
Well the caps should be in Thursday, so I did a little more investigating
All the wires had 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
 

wa5cab

Downloads Moderator
Staff member
H-M Platinum Supporter ($50)
Joined
Dec 25, 2011
Messages
4,271
Likes
1,029
#4
That will probably start and if so, run. But you risk losing the start winding over the long haul because you are depending upon the two run windings to have the same voltage across them, and they won't during start-up because of the fact that the start winding momentarily has to draw all of its current through the other run winding. So don't cheap out, but tie 6 to the hard neutral as I said. And let the pole pig worry about it.

I have no way of knowing which direction it is going to turn.
 

randyjaco

Active User
H-M Supporter - Gold Member ($25)
Joined
Oct 5, 2010
Messages
801
Likes
311
#5
Robert, are you saying that I should do this?

1 and 5 to L1
4 to L2
2 and 3 Joined
6 to Neutral
 

wa5cab

Downloads Moderator
Staff member
H-M Platinum Supporter ($50)
Joined
Dec 25, 2011
Messages
4,271
Likes
1,029
#6
Yes. And for the other direction:

1 & 6 to L1
4 to L2
2 and 3 Joined
5 to Neutral

Or

1 to L1
4 and 5 to L2
2 and 3 Joined
6 to Neutral

The pole pig is just a big step-down transformer with a 240 volt center-tapped secondary. The center tap is grounded at the pole and is the Neutral. The two ends are L1 ans L2.
 

markba633csi

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Apr 30, 2015
Messages
2,822
Likes
1,467
#7
Actually, standard practice for many dual voltage motors is not to use the neutral (for 240v operation) and simply parallel the start leg across one of the run windings, like Randy's original proposal in post #3.
The midpoint junction of the run windings typically stays close enough to zero volts (for several electrical-y reasons) so the start leg never sees much more than 120 volts. But you can certainly use the neutral as Robert mentioned- your start caps might live just a tiny bit longer. (electrical-y reasons again)
mark
 
Last edited:

randyjaco

Active User
H-M Supporter - Gold Member ($25)
Joined
Oct 5, 2010
Messages
801
Likes
311
#8
What is a
That will probably start and if so, run. But you risk losing the start winding over the long haul because you are depending upon the two run windings to have the same voltage across them, and they won't during start-up because of the fact that the start winding momentarily has to draw all of its current through the other run winding. So don't cheap out, but tie 6 to the hard neutral as I said. And let the pole pig worry about it.

I have no way of knowing which direction it is going to turn.
What is a Pole Pig?
 

markba633csi

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Apr 30, 2015
Messages
2,822
Likes
1,467
#9
Ha. A pole pig is the big round distribution transformer on the pole outside your house. Can't put lipstick on it. Nor would you want to. Oink!
mark
 
Last edited:

wa5cab

Downloads Moderator
Staff member
H-M Platinum Supporter ($50)
Joined
Dec 25, 2011
Messages
4,271
Likes
1,029
#10
Right. I first heard the term used back in the late 1940's I think.
 

randyjaco

Active User
H-M Supporter - Gold Member ($25)
Joined
Oct 5, 2010
Messages
801
Likes
311
#11
Well, the caps came in. I installed them and when I flipped the switch the motor spun right up like a new one. Yea, it spun clockwise. I only had a few minutes to play with it, so I still have questions. I did put a mechanical tachometer on the shaft and got exactly 1800 rpm.
The wire up was:
L1-- 1 and 5
L2-- 4
2 and 3 joined
6 -- neutral

I was hoping it was it was going to be a 3450 rpm motor and someone stated that it should be one. In fact, if it were a compressor motor it should be a 3450 motor. So, I am wondering if I should look at my wiring set up?

As I stated earlier, I know nothing of its history. Judging from the metric fasteners used and the rough finish of the castings, I am guessing it is Chinese and used on something heavy duty like a compressor due to the fact that the motor and shaft are so large. The wires are @ 10 gauge. The shaft is 1.125", so I would think that it is 5 or more horsepower. I need to know about what horsepower the motor is. Of course, there is no spec plate so, I cannot calculate it. The motor is running free and at this point, I have no way of adding a load.
Is there any way to estimate the HP of the motor? I have a clamp over watt meter, but I doubt that it's drawing many amps running free.

Thanks again for all the help
Randy
 

markba633csi

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Apr 30, 2015
Messages
2,822
Likes
1,467
#12
Hi Randy- 1800 is it, only way to spin it faster would be to feed it 120 cycles from a VFD and it may overheat if you did that.
Sounds like it would be useful to make a RPC with it...
mark
 

randyjaco

Active User
H-M Supporter - Gold Member ($25)
Joined
Oct 5, 2010
Messages
801
Likes
311
#13
Well, I was hoping :cool:
Luckily I have some pullies that will double the cutter speed.
Thanks All for the help.

Randy
 
[6]
[5] [7]
Top