# Capacitor Question



## randyjaco (Jan 22, 2016)

I have a 230vac single phase coolant pump motor that has crapped out. The motor will run if I give it a spin to start it. So, I presume it is a capacitor problem. (I am electronically challenged) 
The motor is a 1/8hp Taiwanese gem. I pulled the capacitor and carried it to several electrical supply houses. They looked at it as if they had never seen one before and immediately told me that they didn't have one and didn't know where I could find one. 
It is@ 7/8" in diameter and @1.5" long. Printed on it is 15uF, 230W.V.AC., Shihlin Electric, 68102 and  MP CON (The "O" is questionable). 
Can anyone tell me what this is and what I might replace it with. It doesn't have to be the same size and shape. I just need the motor to run. 

Thanks 
Randy


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## chips&more (Jan 22, 2016)

Try this “15 mfd 230vac capacitor” search on the net…Dave.


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## CluelessNewB (Jan 22, 2016)

I believe that is a "Motor Run" capacitor rather that a "Motor Start" capacitor.   You can replace it with any "Motor Run" capacitor rated for about 15 uF and at least 230V (more is fine). 

Here is one from McMaster-Carr rated for 15 UF but 370 Volts.  Its physically a bit larger.  

http://www.mcmaster.com/#7602k65/=10ssa3d


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## TOOLMASTER (Jan 22, 2016)

shapes may very
but 15 uf 230 v is what you need

run cap..
my Taiwan  lath used the same one.....did you notice the motor running hot?


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## John Hasler (Jan 22, 2016)

Check for a stuck or burned centrifugal switch.  The first step in doing that is to give the end bell a healthy thwack with a hammer.  The next is to pull the end bell, examine and if possilble clean up the centrifugal switch contacts, clean the tar that used to be grease off all the moving parts, and relubricate.


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## 4GSR (Jan 22, 2016)

Your capacitor is not the problem.  You have something wrong or out on the starting circuit.

edit: John beat me to it!


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## Chipper5783 (Jan 22, 2016)

Single phase motors need some sort of a "Start" mechanism.  The are a few different methods.  Usually there is a second winding that is only used during starting (kicks out with a centrifugal switch, or a current sensing relay).  Sometimes there is a capacitor in the circuit of the start windings (and so is called a "Starting Capacitor").  Figure out what sort of arrangement this manufacturer uses to get the motor going, than look for problems in that circuit (failed capacitor, burnt open start winding, goofed up centrifugal switch).

Let us know how it works out.


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## randyjaco (Jan 22, 2016)

Wow, that didn't take long 8), thanks for the replies.
I was wondering if it was a run or  start? It is good to know that higher voltage is OK. That will make it easier. 
Yes  Tool master, it does run very hot now. Would that indicate that it is a run? 

Randy


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## TOOLMASTER (Jan 22, 2016)

4gsr said:


> Your capacitor is not the problem.  You have something wrong or out on the starting circuit.
> 
> edit: John beat me to it!




THATS WHAT I THOUGHT WITH MY LATHE...IT WAS THE RUN CAP


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## randyjaco (Jan 22, 2016)

There is no centrifugal switch in this motor.


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## TOOLMASTER (Jan 22, 2016)

NEW RUN CAP SHOULD FIX IT UP


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## silence dogood (Jan 22, 2016)

If you do need to replace the capacitor,  make sure that the voltage rating is VAC not VDC.  In this case, the McMaster-Carr cap should work.


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## f350ca (Jan 22, 2016)

Its probably a run capacitor, just replaced one in my bench grinder. It doesn't have a centrifugal switch either. If you take the capacitor to a motor rewind shop they can test it to be sure.

Greg


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## TOOLMASTER (Jan 22, 2016)

GOOD INVESTMENT


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## CluelessNewB (Jan 23, 2016)

randyjaco said:


> I have a 230vac single phase coolant pump motor that has crapped out. The motor will run if I give it a spin to start it. So, I presume it is a capacitor problem. (I am electronically challenged)
> The motor is a 1/8hp Taiwanese gem.



From the original question you will note that this motor is for a coolant pump and is only 1/8 hp.  These two pieces of evidence are hints that this is a capacitor run motor (rather than a capacitor start).   Since it is a coolant pump it would not require much starting torque and it's small size make efficiency less important.  The last clue is the small size of the capacitor 15uF is rather small, most starting capacitors are 100uF or more.


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## Bill C. (Jan 23, 2016)

chips&more said:


> Try this “15 mfd 230vac capacitor” search on the net…Dave.


Might try a Heating and AC shop, that reminds me of a blower part.  The mfd and Voltage are the critical part.  

I see you have already removed it, be careful those big capacitors can hold nasty charge for a long time.  Even the small ones can, we would ground both legs together to short them out.


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## mksj (Jan 23, 2016)

The biggest problem will be trying to find a replacement that is small enough with the same ratings, most of the ones I have seen are 250 or 370 VAC and are bigger. The one in my coolant pump is rectangular. Be sure to insulate the connections so nothing shorts out.  I would look under fan, AC and/or pool equipment. One of these capacitors may also work.
http://www.ebay.com/itm/1pc-AC-Star...748843?hash=item1e81166aab:g:TkMAAOxyOypSVP9a
http://www.ebay.com/itm/Capacitor-1...492386?hash=item4d28a6a7e2:g:HbIAAOSwPcVV1yiQ


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## John Hasler (Jan 23, 2016)

CluelessNewB said:


> The last clue is the small size of the capacitor 15uF is rather small, most starting capacitors are 100uF or more.


15 uF is actually rather large for a run cap on a 1/8 hp motor.  I agree that motors that small usually have a only a run cap, though.

[Edit] The dimensions are rather small for 15uFd.  Might it actually be 1.5uFd?  That would be about right for a run cap for 1/8 hp.  It also looks like there's space between the digits for a decimal point that may have gotten scraped off.


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## Ulma Doctor (Jan 23, 2016)

as a point of information,
you can replace the capacitor in question with a 15uf cap of any voltage rating that is equal to or larger than the 230v
for example a capacitor with a 15uf- 440v rating would work just as well
or 15uf @277v

a capacitor can only store dc voltage like a battery, even if you apply AC voltage to it.
the voltage doesn't increase if you were to use a 440v rated cap, the voltage out of the cap is the same as the highest applied voltage.
the 440v in this example is what voltage the cap is safe to use, the 15uf is the stored charge capacity in micro-farads .

in summary, your uf rating should be very close to the original, but the voltage can be substituted as long as you use an equal or higher rating.

oil filled capacitors run cooler and generally last a lot longer too, i'd recommend their use whenever possible or prudent.

i hope the information is helpful to someone.


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## Ulma Doctor (Jan 23, 2016)

randyjaco said:


> There is no centrifugal switch in this motor.



the centrifugal switch may be hidden inside the motor, opposite of the shaft end.
it may not be visible, but most likely exists.
the centrifugal switch is responsible for applying the capacitors power to the starting circuit.
when the motor gets up to speed the start circuit opens and no more power flows from the cap to the start circuit until the motor slows to a predetermined point.
then the cap is called into circuit once again by a reduction in centrifugal force which in turn closes the start circuit and the caps charge is dumped into the start circuit once again until the motor speed opens the centrifugal switch once again.


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## RJSakowski (Jan 23, 2016)

I replaced the capacitor on my coolant pump motor.  I found a film type capacitor in my junk box that I tried and it worked, even though the capacitance didn't match the OEM value ( I think it was something like an 8uFd for a 10 uFd).  It has been working for four years now with no problem.


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## atunguyd (Jan 23, 2016)

TOOLMASTER said:


> GOOD INVESTMENT
> 
> View attachment 119961


Not really, often what changes in a capacitor is its ESR value (equivalent series resistance) so while the capacitance had not changed, the capacitor has developed an unnecessarily large parasitic resistance. This results in more voltage across your capacitor and less across your other components. 

You need something that measures capacitance and esr to check if a capacitor is still good. 

I recently fixed a ups, problem was one small capacitor, capacitance was fine but esr was 48ohms (should be like 0.4)

Sent from my SM-N920C using Tapatalk


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## atunguyd (Jan 23, 2016)

You can get a replacement at any electronics store. 15uF and voltage greater than 200v. Make sure though that it is not an electrolytic capacitor, they don't like AC.  film style will work,maybe a polyster cap. 

Sent from my SM-N920C using Tapatalk


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## mksj (Jan 23, 2016)

atunguyd said:


> Make sure though that it is not an electrolytic capacitor, they don't like AC


Not really correct, there are different rating for different capacitors types, some work better then  others in certain applications. CDE and other capacitor manufactures make AC motor start specific non-polar or bi-polar electrolytic capacitors.
http://www.cde.com/catalogs/PSU.pdf
http://www.elcomp.net/conis.pdf
The advantage of electrolytic is size, comparable film and oil types are much larger. Most likely the capacitor that went bad is an electrolytic, possibly film based on its size and VAC rating.  The negatives of electrolytic types are heat leads to rapid degradation and they have a shelf life, they will not last as long as a MKP film or oil type. They are usually only used for motor starting capacitors and not run. My experience in having them go bad in motors, is when they go, you measure near 0 capacitance, if the ESR increases, they cook and go  bad very quickly in these applications. Also rapid on off cycling of single phase motors, causes heat buildup in the capacitors which leads to rapid failure. Capacitors in circuits, is a different story, ESR, leakage etc. are important to measure based on the circuit application.

In this application I would look for a encapsulated film type (MKP) 15-16uF and a minimum voltage rating of 250VAC, oil will probably be too large.


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## atunguyd (Jan 23, 2016)

Agreed, you do get non polarised electrolytics but they are not common and as per my advise if you go to an electronics store and buy one the chances are very high you will get a polarised version. 

Sent from my SM-N920C using Tapatalk


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## John Hasler (Jan 23, 2016)

atunguyd said:


> Agreed, you do get non polarised electrolytics but they are not common and as per my advise if you go to an electronics store and buy one the chances are very high you will get a polarised version.
> 
> Sent from my SM-N920C using Tapatalk


Non-polarized (actually back-to-back) electrolytics are almost always what are used as motor start capacitors.


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## WalterC (Feb 1, 2016)

I have a HVAC company and I have maybe 5 of those on my truck. But this is a useless reply only to make you feel better. 

 If you see a HVAC truck or company or supply house in your area, stop and ask for one, they are very common.


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## toolroom (Feb 3, 2016)

Concerning capacitors, and I am dumber than a bag of hammers on electrical issues, Do they make any noise when they [may] go bad? On my Jet drill the motor is beginning to emit a rattle. I used my stethoscope and it sounds like it is coming from the capacitor. I removed the two screws and looked at it, no leaks or burnt signs so its back up and running. The motor makes no sound with the belt off but kinda growl/rattles when the belt is looser or tighter.
Any thoughts?
thanks in advance
toolroom


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## JimDawson (Feb 3, 2016)

toolroom said:


> Concerning capacitors, and I am dumber than a bag of hammers on electrical issues, Do they make any noise when they [may] go bad? On my Jet drill the motor is beginning to emit a rattle. I used my stethoscope and it sounds like it is coming from the capacitor. I removed the two screws and looked at it, no leaks or burnt signs so its back up and running. The motor makes no sound with the belt off but kinda growl/rattles when the belt is looser or tighter.
> Any thoughts?
> thanks in advance
> toolroom



That sounds more like a bearing issue.  Normally when caps fail with noise, they either go BANG or BBBzzzzzzzzT  Sometimes accompanied by clouds of smoke.


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## toolroom (Feb 4, 2016)

Jim,
     Exactly what I thought, but again, listening through the stethoscope ... Guess I'll run it till the bearing fails.
Thanks again


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## Ulma Doctor (Feb 4, 2016)

i have heard capacitors whine before they blow up, it's an unmistakable sound


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## TOOLMASTER (Feb 4, 2016)

motor will get hotter as the cap wears out...it changes the phase..think of it as engine timing


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## randyjaco (Feb 14, 2016)

For those of you that recommended replacing the run cap, you were right. I  finally got one and the old motor runs like a new one. 
Thanks for the help. 
Randy


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## hermetic (Feb 15, 2016)

Glad you got it sorted Randy. They do some times buzz or whine, but the next thing that happens is usually a loud bang followed by a snow shower of waxed paper and aluminium foil, so I would not recommend listening with a stethoscope if it IS the capacitor making a noise! Seriously, you have illustrated an important point for all here in that a start or run capacitor can go bad gradually, and cause noise and reduced motor efficiency when it does. 
Phil


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