Capacitor Question

[TOOLMASTER]

NEW RUN CAP SHOULD FIX IT UP

 

[silence dogood]

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.

 

[f350ca]

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

 

[TOOLMASTER]

GOOD INVESTMENT

 

[CluelessNewB]

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.

 

[Bill C.]

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.

 

[mksj]

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

 

[John Hasler]

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.

 

[Ulma Doctor]

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.

 

[Ulma Doctor]

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.