Running capacitor for motor

[happymachinist]

So the running capacitor on a spare motor I have is shot. I had a hard time finding one the right physical size and correct uF. I found a cheap one on amazon that was close enough in size and required 60uF.

Upon arrival I measured it with my fluke meter and it reads at 81uF!! I understand the tolerance for most capacitors is +/- 6% and understand the capacitor I received is way out of spec...thanks China. I am assuming the spec motors are made to are also in the +/-6% range also.

What would the issues be in running this capacitor? I might try to find another capacitor again but this is just a spare cheapo Taiwanese motor and don't want to dump a bunch of money in it.

Is it dangerous to run this capacitor, will it just lead to diminished motor life or excess heat? Any input would be appreciated.

Thanks

 

[Bert_]

So the running capacitor on a spare motor I have is shot. I had a hard time finding one the right physical size and correct uF. I found a cheap one on amazon that was close enough in size and required 60uF.

Upon arrival I measured it with my fluke meter and it reads at 81uF!! I understand the tolerance for most capacitors is +/- 6% and understand the capacitor I received is way out of spec...thanks China. I am assuming the spec motors are made to are also in the +/-6% range also.

What would the issues be in running this capacitor? I might try to find another capacitor again but this is just a spare cheapo Taiwanese motor and don't want to dump a bunch of money in it.

Is it dangerous to run this capacitor, will it just lead to diminished motor life or excess heat? Any input would be appreciated.

Thanks

I'm guessing it would be ok. It will cause some extra current through the start winding. Probably not enough to cause problems. But that's just a guess.

Have you checked any other caps to verify meter function?

 

[happymachinist]

Have you checked any other caps to verify meter function?

Yes I’ve checked a few brand new caps, and referenced the meter vs a couple others.

 

[6PTsocket]

So the running capacitor on a spare motor I have is shot. I had a hard time finding one the right physical size and correct uF. I found a cheap one on amazon that was close enough in size and required 60uF.

Upon arrival I measured it with my fluke meter and it reads at 81uF!! I understand the tolerance for most capacitors is +/- 6% and understand the capacitor I received is way out of spec...thanks China. I am assuming the spec motors are made to are also in the +/-6% range also.

What would the issues be in running this capacitor? I might try to find another capacitor again but this is just a spare cheapo Taiwanese motor and don't want to dump a bunch of money in it.

Is it dangerous to run this capacitor, will it just lead to diminished motor life or excess heat? Any input would be appreciated.

Thanks

The tolerance on motor capacitors is very broad, probably more like 20%. Don't give it a second thought. Use it. Just don't ever use a start cap for a run cap, even if the value is correct. They are not meant for contiuous duty and it will fail very quickly. Many motor caps are listed with a range of values on them rather than a tolerance.

Sent from my SM-G900V using Tapatalk

 

[happymachinist]

The tolerance on motor capacitors is very broad, probably more like 20%. Don't give it a second thought. Use it. Just don't ever use a start cap for a run cap, even if the value is correct. They are not meant for contiuous duty and it will fail very quickly. Many motor caps are listed with a range of values on them rather than a tolerance.

Sent from my SM-G900V using Tapatalk

Awesome! Thanks for the input like I said it’s a cheap (free) used motor and if its longevity goes down a bit I’m not out much.


Sent from my iPhone using Tapatalk Pro

 

[American Locomotive]

The tolerance on electrolytic start capacitors is pretty large, usually around 20% or so. However the tolerance on run capacitors is typically much tighter.

81uF vs 60 is +35%, which is huge. I would expect the motor to run a lot hotter, and consume more power.