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Help Me/ hook up a forward-stop-reverse motor cont switch on a 220volt mill machine

sea

Mar 28, 2012
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Ok, I will rephrase:

The centrifugal switch is not creating friction on the switch at stop/initial start-up

The switch on my model is not depressing the contacts to allow the Start cap to be in the circuit

The run cap gets the machine going after I flick the spindle with high whine sound being heard at this point if you do not flick the spindle

Prolly why my run cap blew up to begin with, start cap was fine (its only using the run cap for everything)

So basically:
"centrifugal switch never allows the start capacitor to work kick in, which is why I had to give the spindle a flick to get it to spin at full speed most of the time even before the switch went bad, its starting only on the run cap side"
 

john monks

Mar 9, 2012
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In this motor the start winding is used for starting and running.
The hand drawn schematic show that one capacitor or the other is switch in series with the start winding, presumably the large capacitor for starting and the small capacitor for running.
Incidentally I noticed that one schematic I noticed on line for this motor both capacitors are in series and I supposed that the switch was in parallel with the small capacitor (a little hard on the switch). But either way the effect is the same.
If the hand drawn schematic is correct I wonder if it was harder to flick start the motor one way over the other.
I'm glad you got it going. For me this is a learning experience.
 
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CDRIVE

Hauling 10' pipe on a Trek Shift3
May 8, 2012
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Ok, I will rephrase:

The centrifugal switch is not creating friction on the switch at stop/initial start-up

The switch on my model is not depressing the contacts to allow the Start cap to be in the circuit

"

Why not disassemble the motor and see if you can fix the start switch. It should be closed at rest. Maybe you lost a spring or the contacts need to be cleaned and resurfaced. The CS is a simple assembly and usually requires removing only one end bell.. 'four nuts'.
 

CDRIVE

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In this motor the start winding is used for starting and running.
The hand drawn schematic show that one capacitor or the other is switch in series with the start winding, presumably the large capacitor for starting and the small capacitor for running.

Start windings draw 2 to 3 times the run current. They're never left in the circuit because they are intended for intermittent duty only. They will fry in short order if not disconnected quickly. I will not argue that his friend got the motor going but I don't believe the schematic he drew is correct. As I said before but I'll reiterate. The Run Cap is not switched in and out. It's wired permanently in series with the Run winding. Cap Start - Cap Run motors are the most efficient of all the Split Phase designs.

If you don't believe me.. Google it.
 

john monks

Mar 9, 2012
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I don't wish to argue either. I did google this type of motor and you're right, they are very efficient.
You are only partly right about the other, that is the start winding is still in the circuit to some degree in the run condition.
Going by the hand drawn schematic there is a 20uF capacitor in series with the start winding during the run condition. The impedance of this capacitor is about 133 ohms. I don't know the impedance of the start winding but I would assume it to be much lower. The impedance of this string is going to be the difference or 133 ohms - Xl because of the imaginary components of the impedances.
The bottom line is that about one amp is left in the start winding during the run condition and this is heavily capacitive. The stator windings will be somewhat inductive and that should counterbalance some of the capacitive reactance.
If the schematics I saw on line are correct then this effect will still be about the same.
Keep in mind that this is a two capacitor motor one 150uF and the other 20uF.
 
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CDRIVE

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John, please post a link with the design you describe. I've never seen one and the design makes no sense to me. That said we all make mistakes and if I've made one I'll gracefully concede to it. So, as they say in Missouri.... :D

Chris

BTW, the caps aren't used for impedance matching. Think phase angle. ;)

Edit: John, see my next post.
 
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sea

Mar 28, 2012
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"If the hand drawn schematic is correct I wonder if it was harder to flick start the motor one way over the other."

John:
No its the exact same as far as starting, the only effect in this is when using different gears on the machine, pick a low speed gear, which uses alot less torque on the motor and it starts much easier, a high speed gear very tough to start, being its using alot more torque to start I would guess, though this was exactly the same as before switch change, no difference.

He ended up using my post #14, that is the correct schematic of the windings (220 volt)

Though he did only use three wires going up to the motor, not the 4 wires that all the schematics use, 3 wires was how it was originally wired but the proper schemtaics did not exist

Though once running its fine and no issues once motor is in movement, its power is as should be


"Why not disassemble the motor and see if you can fix the start switch. It should be closed at rest. Maybe you lost a spring or the contacts need to be cleaned and resurfaced."

I've had this motor apart several times and checked the operation of the switch and used contact cleaner on it, it looked perfect and really did not need cleaned, but I did not at the time know the exact postition of the switch and how to figure out if it was open or closed and if and when that would be the proper position, so thats makes it tough, now I know since I had a guy show me and check it, I do know where it should be, you can not know its position when you have the rotor out of the motor and can not check it, so you need to know how to check it from the outside to even know if its in the correct position or not when its together.

I have video's of the inside of the motor and me replacing the caps and I demonstate the operation of the switch (the springs snap famously like it was brand new, this was my initial problem, I video everything I do extensively when I am not sure what I am doing so i can later put everything back together

I am a total novice at any of this I hope you can understand, I knew nothing about motors or motor control before all this, now i know alot more and am glad of it.
 

CDRIVE

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John, I found a number of diagrams with the design you describe. For certain.. it's painful but as I said, I will gracefully concede. Consider it done. ;)

Chris
 

john monks

Mar 9, 2012
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Drive, I'm sitting in my sister's house and I'm on my iPad so sending you a link may be difficult. Nevertheless the capacitance does some impedance matching but has virtually nothing with the efficiency, it was just a side note. But getting to the main point induction motors loose efficiency because of what is called slip, that is the induce current is moving ahead of the rotor speed causing the shaft to run slow. So a little bit starting or leading magnetic field ahead of the field induced by the rotor helps keep the rotor from lagging as much behind the induced magnetic field.in the rotor.
This is why some AC current is maintained in the start winding. This increases efficiency.
Please, you are not obligated to concede anything to me. I only ask you to look at this. I don't mind answering blogs at all because it keeps my mind fresh and for that I'm thankful.
 
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CDRIVE

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Please, you are not obligated to concede anything to me.

Yes I am. I said it and I was dead wrong. It's not the first time and I doubt that it will be the last. :D Did you know that Crow is rather chewy? :rolleyes:

So, the question remains .. The engineer friend drew the CS as a SPDT, that switches either the Start or the Run Cap in. Do you think this is the way it's wired? Schematics I found show this method and SPST, where the Run Cap is hard wired and paralleled with the Start Cap through the CS.

Sea, did your friend test the Start Cap with an Ohmmeter? When they fail they usually leak but it's not impossible for them to open.

Also, please use the forum's "Quote" or "Multi Quote" function. It will make reading your posts easier. ;)

Chris
 

john monks

Mar 9, 2012
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Yes I believe the CS or centrifugal switch is a SPDT or single pole double throw switch.
 

CDRIVE

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Too bad that all split phase motors don't have access to the CS like this one. It took me more time to remove it from my drill press than to access the switch. It only required removing an end cap that is nothing more than a cover plate.

I had just finished replacing a 120V motor on my stationary belt sander with a 240V model. I always test for leakage or shorts from the hot and neutral to ground and this time wasn't any different. I figured, while I was at it, I'd test the rest of my machines. Imagine my surprise when I measured a dead short from neutral to ground on my drill press that I've had for over 36 years. A GFI would have caught this but they can be a nuisance in a shop environment.

This problem had to have manifested itself from day one but because the CS is in the neutral leg and not the hot it ran flawlessly all these years. I fixed it by removing the CS and rotating it 180 deg. This placed the contact over an empty area with no bearing web underneath it to short to.

Chris
 

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sea

Mar 28, 2012
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Sea, did your friend test the Start Cap with an Ohmmeter? When they fail they usually leak but it's not impossible for them to open.


Chris

Yes he checked the ohms, he did did it pretty fast but I saw him take several tests with it and had one of the leads removed off the start and the run cap at some point when testing

Ohh sorry I read this wrong I thought you meant the switch, I dont know the cap answer I was in and out of shop
 

CDRIVE

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Ohh sorry I read this wrong I thought you meant the switch, I dont know the cap answer I was in and out of shop

Well, if you get tired of manually starting the motor you may want to test the start cap. I know I mentioned this before but I'm not sure if I actually asked this... When you turn the motor on does any sound emanate from it at all, prior to spinning it?
 

Pring

Jul 15, 2017
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With regards to single phase 220v two capacitor motor, if Z2W2 has a V2 out wire that will be connected, what will happen to the motor?
I need your help, pls... thanks
IMAG0092.jpg
 
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