# Motor Help



## GEORGE D (Apr 2, 2009)

Anyone good with these types of induction motors? Basically I'm trying to bench test with my 289, just not exactly sure what I should be reading or really looking for. There are 3 wires going into motor but doesn't make sense 



















with diagram. Any help is really appreciated.


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## JRaef (Mar 23, 2009)

Looks like a standard PSC (Permanent Split Capacitor) single phase motor wiring diagram, albeit with Chinese characters instead of numbers we can read. 










The subtle difference in the connection of the wires going to the windings with relation to the capacitor makes it spin one way or the other.


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## GEORGE D (Apr 2, 2009)

JRaef said:


> Looks like a standard PSC (Permanent Split Capacitor) single phase motor wiring diagram, albeit with Chinese characters instead of numbers we can read.
> 
> The subtle difference in the connection of the wires going to the windings with relation to the capacitor makes it spin one way or the other.


You nailed it once again, this is a motor that someone handed me and asked if I could get one or get it repaired and I said sure. He said it was bad, it would barely spin and he could stop it with his fingers. Later that day I happened to be working on another piece of equipment that had same type of motor doing same thing and it turned out being loose capacitor on board. I'm pretty confident it's gonna be the cap for this one as well. How exactly does a cap work in this scenario? It seems being an induction motor it would spin regardless of the capacitor but obviously not.


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## Jlarson (Jun 28, 2009)

No good capacitor no phase shift between the start and run winding so no rotating magnetic field to get things spinning.


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## GEORGE D (Apr 2, 2009)

Jlarson said:


> No good capacitor no phase shift between the start and run winding so no rotating magnetic field to get things spinning.


Could you elaborate, I'd really like to get this?


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## JRaef (Mar 23, 2009)

GEORGE D said:


> Could you elaborate, I'd really like to get this?


So look at the diagram I posted above. If you notice, the capacitor is in series with one winding. This in effect creates a polyphase (2 phase) motor from a single phase source. The capacitor in series with one of the windings adds in a capacitive time lag in the power going through it, so the magnetic field created by that winding lags the magnetic field created by the other winding by just a bit, enough to make the motor spin in that direction. If the cap is bad, i.e. shorted, there is no difference between the two windings and the motor is just a heater, nothing rotates. If the capacitor is open, you now only have one winding, again no difference in the magnetic fields, so no rotation. 

Huh, I just noticed that the drawing I linked to is actually NOT showing the reversing function, sorry! It is apparently just showing an alternate connection. But if you wanted to reverse that motor, you would move the connections so that the capacitor would be in series with winding L1 and R, instead of L1 and S.


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## GEORGE D (Apr 2, 2009)

Okay finally got to work on this motor I initially thought capacitor was bad because I tried putting a larger capacitor (it's all I had from hid fixture), motor worked fine. The problem initially was that it would spin but could be stopped by hand. I measured resistance on it and a known good one and they both measured same. Any help is always appreciated.


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## GEORGE D (Apr 2, 2009)

Sorry I forgot to mention I replaced with the original size capacitor and now the motor does not have enough torque.


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## Bootss (Dec 30, 2011)

GEORGE D said:


> Sorry I forgot to mention I replaced with the original size capacitor and now the motor does not have enough torque.


Run or start winding might be open or maybe they're cooked.


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## xlink (Mar 12, 2012)

JRaef said:


> Huh, I just noticed that the drawing I linked to is actually NOT showing the reversing function, sorry! It is apparently just showing an alternate connection. But if you wanted to reverse that motor, you would move the connections so that the capacitor would be in series with winding L1 and R, instead of L1 and S.


The likelihood of an error increases by the square of the number of people who will see ti.


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## GEORGE D (Apr 2, 2009)

Ok I'm officially f&cking stumped, changed motor and cap and still same problem, the only thing that seems to give it enough ass is oversized cap, but surely that ain't healthy. The motor turns (both new and old) with original cap but can be stopped by hand. Here is diagram, any help is appreciated.


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## 8V71 (Dec 23, 2011)

Why does "check rotation" keep going through my mind. :whistling2:

What is that SC-12 thingy George?

edit...I see it now, motor controller. That or the associated circuitry would be my guess.


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## GEORGE D (Apr 2, 2009)

8V71 said:


> Why does "check rotation" keep going through my mind. :whistling2:
> 
> What is that SC-12 thingy George?
> 
> edit...I see it now, motor controller. That or the associated circuitry would be my guess.


Yeah that thing is some controller in the form of a big cube relay. I should of took pics but forgot, I was so fed up just wanted to walk. Anyhow when I return Ill try replacing it and see if that cures it. If not than I really am walking. Thanks btw.


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## 8V71 (Dec 23, 2011)

It's not exactly precise controlling the speed of an induction motor. Do they change the speed slightly for like tension control of some product? I see the Automatic Decoiler text at the top.


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## GEORGE D (Apr 2, 2009)

8V71 said:


> It's not exactly precise controlling the speed of an induction motor. Do they change the speed slightly for like tension control of some product? I see the Automatic Decoiler text at the top.


They do change speed for certain jobs. They set desired speed then an arm is pulled by tension on cable causing motor to spin. What baffled me was that the motor works with larger capacitor. I would of imagined that if there was an issue with one leg or controlled leg that a larger cap wouldn't help but obviously I must be wrong. Since I've eliminated motor & cap that only leaves one thing, although I will mention that the "new motor" was actually used from eBay but am confident it was good.


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## stuiec (Sep 25, 2010)

If it were convenient, I would test run it w/out the controller. You appear to have it wired correctly.

View attachment 25305


View attachment 25307


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## Search Party (May 23, 2013)

Hey George
How did you go with the motor?

The speed is dtermined by the number of poles and the frequency of your supply as well as the torque of the mototr and the load you have it attached to.

Your problem was simply the designed cap was too small.
It was not a problem replacing it with what you called and over sized cap
The size of the cap determines the amount of torque the motor provides because the larger the cap, the larger the phase angle shift and so the more torue the motor will deliver.
A differnt towque agle of 90 deg will provide you woth the maximum torque that motor will give you.
Run the motor with a selection of differnt size caps and choose the cap that provides you with the best start and running conditions for you.

Dale


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## GEORGE D (Apr 2, 2009)

Search Party said:


> Hey George
> How did you go with the motor?
> 
> The speed is dtermined by the number of poles and the frequency of your supply as well as the torque of the mototr and the load you have it attached to.
> ...


So are you saying that even double the size of original cap is ok?


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## 8V71 (Dec 23, 2011)

Search Party said:


> Hey George
> How did you go with the motor?
> 
> The speed is dtermined by the number of poles and the frequency of your supply as well as the torque of the mototr and the load you have it attached to.
> ...


I think this is bad advice in this case. Unless George sez otherwise I believe this is an engineered machine that stopped working. Adjusting the cap value to correct a different problem wouldn't be wise at all.


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## Search Party (May 23, 2013)

George

Measure the resistance of both the windings, if they are the same resistance, then it is a permenant split pahse motor (Which uses a permenanly connected capacitor to one of the windings that remains in service for normal operation of the motor)

And if the resistance is the same, than the windings are fine.

The size of the capacitor is engineering depending on the amount torque that is required during the nomal running condition of the motor. (As opposed to a cap start / cap run moror where the dual capacity of the caps are for starting torque)

The worst thingyou are going to do in 'oversizing' the capacitor is push the phase shift past 90deg which will simply start to reduce your torque as 90deg is the optimal angle.

The normal angle for a permenant split phase is around 30deg, so even if the original cap is providing upi 30deg (which is obviously very doubtful) you have a long way to go to achieve 90deg.

The only problem to be careful of with increasing the size of the cap is being aware of not exceeding the troque reqired for the load - you do not want to tear the load apart if your motor creates too much torque and tears the belt or whatever it is connected to

Dale


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## GEORGE D (Apr 2, 2009)

Search Party said:


> George
> 
> Measure the resistance of both the windings, if they are the same resistance, then it is a permenant split pahse motor (Which uses a permenanly connected capacitor to one of the windings that remains in service for normal operation of the motor)
> 
> ...


In this case I should be fine, the load isn't affected by torque. Thanks by the way, very useful info!


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