Wiring up a new coolant pump

David Pollard

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Nov 24, 2017
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Hi Everyone,
I went to use my coolant pump on my Hafco HM50 Mill the other day. I have never used it before. The machine is 2nd hand and I always assumed the coolant tank was empty when I bought it. (NOT) When I flicked the switch there was just silence.
As a bit of a background and to make this post slightly more interesting here is what I found when I pulled the pump out.
You can only imagine the gunk in the tank.

DirtyPump.jpg
This is what is left of the drive shaft. It is almost rusted right through.
Shaft.jpg

After seeing this I decided to see if I could buy a new one.
To my surprise I found what looks like exactly the same model.
This is the id plate on the old motor and the new one is virtually identical.

ID-Plate.jpg

Now to the problem. I can't seem to figure out where the wires should go on the new motor.
Here is a pick of the original terminal block with the supply wires still connected.
Note there are two blue and two black wires coming out of the conduit.
And the Earth of course.
Note the two lowest terminals have some kind of jumper between them which I assume is a resistor.
The terminals seem to be labeled

Position, Label Connected Wires
===============================
Top Left V1U2 Black and Blue together
Top Right Z2 Blue
Bottom Left 7W1 Black
Bottom RIght 1U No external connection

Old Wiring Block.jpg

Here is the wiring block on the new pump.
It has the same 4 labels on the block except it is rotated 90 degrees anti clockwise.
Instead of the small jumper (Resistor?) between the terminals marked 7W1 and U1 it has another component covered in something like resin glued into the cap.
That is the two red wires you can see in this pic.
The old motor appears to have 4 wires coming out of it, where the new motor appears to have only 3.
There looks to be nothing connected from the motor to Z2.

New Wiring Block.jpg

The big question.
Where do I connect the two blue and two black wires so I don't let the smoke escape and my pump doesn't blow bubbles instead of suck :)
As the black and blue wires from the power supply look otherwise the same I have tied to two that were paired up together in case that make any difference.

Any assistance greatly appreciated.
David.
 

RobertB

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A clear picture of the component in the cover cap would maybe help determine it's function (size and shape at least). Do you have the capability to measure resistance and capacitance? Just a guess, but it's possible 2 of the wires from the conduit go to an external capacitor.

This may help:
 

markba633csi

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Your motor is called a PSC or Permanent Split Capacitor type. Also called a "capacitor-run" motor, as opposed to "capacitor-start"; the capacitor is in the circuit continuously when the motor runs.
There are two windings and a capacitor (the 2uF on your old nameplate is the capacitor value in microfarads)
Here is a typical diagram:
pscmot1.jpeg
I'm thinking the blue and black leads on your old motor represent the two windings and the capacitor is located inside the case?
Once you can identify how the old one is wired then wiring the new one should be easy. Mark
 

David Pollard

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Thanks for your detailed responses.
I did go and watch some Youtube videos about single phase motors last night to refresh my memory.
I also did some multimeter tests on my new motor this morning and I realised I didn't quite read those labels correctly. (They aren't very clear)

The thing in the cover is a capacitor.
CapacitoryCover.jpg
And its wired like this to Z1 and U1
CapacitoryCover2.jpg

I took some measurements with my multimeter.
Resistance confuses me a bit and I don't have a auto ranging meter.
The first reading was on the 200 scale and the third reading was on the 2K scale.
Measurements.jpg

There is a capacitor in the electrical box at the back of the machine and the two blue wires appear to go to it.
Box Capacitor.jpg

The two black wires appear to go to the coolant pump switch but they disappear inside another conduit and then up the inside of the machine.
Here is a picture of the switch with two black wires and a red wire coming out of it.
Switch.jpg

So there are actually two capacitors and the one that came with the new motor is wired to U1 and Z1 when the motor was shipped.
I hope that is enough information now so someone can tell me.....
"The blue ones go here and the black ones go here" :)

I still don't understand what is going on.
Now the switch appears to have the active (Red) coming in and the two black ones coming out go down to the Motor.
I assume the black ones both have power when the switch is on. I haven't tested this.
If the two blue wires go to the capacitor in the box at the back where is the neutral?

Thanks again
David.
 

RobertB

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Your new motor has the capacitor built into the cover, so the old capacitor(blue wires) will not be needed on the new motor. Take voltage readings at the switch and motor if you can. Your resistance readings do not make sense. If Z1 to U1 is zero ohms then V1 to U1 and V1 to Z1 would have to be exactly the same. Did you mean zero ohms when you wrote that(shorted) or infinite resistance(open circuit)? ( Disconnect the capacitor when checking the resistance.)
If you meant infinite resistance your power wires should go to V1 and Z1
 
Last edited:

David Pollard

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Hi Robert,
Thanks for replying so quickly.
Your are right when I wrote 0 ohms I meant there is no connection. My multi meter says 0L I think when there is no connection and 0.00 when there is no resistance. Sorry for the confusion this obviously isn't my day job :)
I'm not game to take voltage readings as my metre only has probe type electrodes and I don't want to get my fingers that close to live wires especially when they are dangling and not connected to anything. I'm more of a 12v kind of guy, with 240v if I'm poking wires the machine is off and the plug hanging where I can see it.
I'll just connect the two black to V1 and Z1, and get the blue ones out of the way so they can't short anything then stand well back :)
David.
 

David Pollard

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In short I can say that it works :)
You wouldn't believe it though. I first turned it on and it made some rattly sounds like there was something loose inside and then it just hummed.
I immediately turned it off and scratched my head a bit. I turned it on again and just a hum.
I checked I had connected the wires as discussed above and they all seemed fine. So I went off and did some other stuff while I thought about it.
What could cause a motor just to humm apart from having the capacitor hooked up incorrectly. Seized? (It's brand new I hear you say)
I pulled the pump back out of the tank and sure enough i couldn't turn the shaft. It spun freely before.
I went back and forward a little bit and it freed up and began spinning normally again.
Turn the switch back on and the pump spins freely.
Tried again and it locked.
You know I'm absolutely sick about **** products coming out of China.
I can only guess that there is a piece of grit in one of the bearings.
After a few goes it seems to be working OK but I'm not confident. I think I'm going to get it all bolted back up and it will run 3 times then lock again.
I'll get back in touch with the company that sold it to me but what are they going to do ask me to send it back. :(
 

turnitupper

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David it seems (to me) that there something jamming the pump itself. Try to flush the pump out thoroughly and ensure that all filters to pump are operational. My $1.35 worth. (US conversion from 2 cents).
John
 

RobertB

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I agree with John, I would check the pump for debris.

It wouldn't make the shaft seize if the wiring were wrong, but I would still double check your resistance measurements with the capacitor disconnected. I didn't notice you had a decimal point in front of the 215 ohm reading. Check both windings with your meter set on the same scale to make sure we aren't off by a decimal place. Your power wires should go to V1 and the other to Z1 or U1, the one with the highest resistance.

One thing to consider if they won't replace it if it is bad is you can use any brand of coolant pump. You just have to get one that matches your power (240v 50Hz) You might have to adapt the mounting holes. Hopefully they will replace it.
 

markba633csi

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Hi David, did you purchase this new pump from a local vendor or thru Ebay or some other vendor? If you used a credit card you should be able to recover your money or have them ship you a new unit.
There sounds like some grit or debris between the rotor and the stator inside the motor case. You might be able to disassemble and clean. If however one of the bearings is bad you shouldn't have to pay for that- I wouldn't
Mark
ps make sure there is no debris inside the pump impeller itself
 

David Pollard

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Hi Guys,
Just a follow up. The wiring suggested is correct, The problem is definitely mechanical.
Feeling the way the shaft turns if feels like bearings to me not rubbish in the impella.
My coolant tank is clean and I haven’t submerged the pump yet so this also makes me think it isn’t the impella.
After a few more on offs and jams and me turning the shaft forwards backwards with my fingers the gritty feeling did not return.
From this I conclude the bearings ground up the debris.

So it’s working ok now. Just not a great out of box experience to say the least.
Thanks heaps for helping me sort out the wiring.
I would not have guessed this is a single compactor motor and that the thing in the cover replaced the capacitor in the cabinet at the back. Now I can make some cuts and add juice
 

David Pollard

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I filled the coolant tank today and turned the pump without the output hose connected.
It gushed out like a fire hydrant straight out of the pump into the bottom of the table.
I connected the hose to the hose barb on the pump and barely a dribble came out of the nozzle.

By the state of the old pump Im guessing the hose is plugged somewhere.
I'm glad I tested the pump with coolant first :)
Next I'll start pulling the hoses and flex pipes off.
I think the previous owner was milling some kind of fiberglass that had a strange reaction with the coolant.
It was certainly corrosive and dried like flour and water.

It will be a nice machine when I'm finished :)
Thanks again guys.
 

ats1911

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Looks like you have it figured out, but for future reference OL probably means overload, which is the same as you should see with the leads not connected to anything.

A good practice is to short the leads together before you make a measurement. You should see zero or very close, which tells you the leads are connected and all is working correctly. Without auto ranging, I typically start on a high range and work down if needed to get better resolution.

Capacitors can take a while to charge/discharge, so when one of those is in the circuit you might have to wait a few seconds for the measurement to stabilize.

Abom79 (Adam Booth) has an old video or three on cleaning up the coolant tank on his Monarch. Gigantic mess.
 

David Pollard

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I always touch the probes together when checking resistance. But good tip!
I like watching Adam and yes I did see his coolant tank clean out video.
I was thinking of him when I was cleaning out my tank.
I used to use a Monarch lathe when I was in my teens during my apprenticeship. Long time ago now.
We never cared what the machines were named.
I only know it was the same machine from the sounds it makes right down to the clutch handle hitting the swarf tray when engaging the chuck to go forwards and the floppy linkages when you disconnect again.
It also had the same taper turning attachment. I never cleaned out that mankey tank :)
 
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