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Need to Match Capacitor Value Exactly??
- Thread starter clubairth
- Start date
a closer match to MFD, with a higher voltage would be better
MBfreak
MEMBER EMERITUS
Start/run capacitor.
Is this the same , ie only one cap installled.
Large value caps, like your proposed 250V 540-640 MFD, are quite often rather unprecisely rated regarding the capacitance value. I would not worry , install it and try it out. If motor drops in rpm when loaded you can always connect a second one of 100 microF in parallell.
Best regards
Ola
Is this the same , ie only one cap installled.
Large value caps, like your proposed 250V 540-640 MFD, are quite often rather unprecisely rated regarding the capacitance value. I would not worry , install it and try it out. If motor drops in rpm when loaded you can always connect a second one of 100 microF in parallell.
Best regards
Ola
rlitman
Well-known member
Is that cap 250VAC or 250VDC rated? The first is ok, the second is very much NOT ok.
joel63
Well-known member
I have been trying to match an 220V air compressor Start/Run Capacitor.
How close do I have to match the MFD?
Mine is labeled with 640-715 MFD but I can't find that exact size?
I have found a 250V 540-640 MFD one.
Would this one work?
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What's the voltage rating of the original capacitor?
BlackJackJim
Member
- Joined
- Oct 31, 2017
- Messages
- 17
I have been trying to match an 220V air compressor Start/Run Capacitor.
How close do I have to match the MFD?
Mine is labeled with 640-715 MFD but I can't find that exact size?
I have found a 250V 540-640 MFD one.
Would this one work?
.
.
.
Electrolytics are anywhere from 10 to 25% off. I would just parallel another 100 ufd cap across your 640-715 ufd. The critical parameter is the voltage rating - you can always go higher wrt voltage rating.
theoldwizard1
Well-known member
Higher voltage and higher MFD are okay. You can take 2 lower mfd, and wire them in parallel to double the mfd.
That sounds like a start capacitor. Run capacitors are usually a much lower value.
Start capacitors are pretty forgiving, as long as the motor starts good with the new capacitor it will be fine even though it's a little smaller. I wouldn't go much larger than the original.
If you do put in a different size of capacitor it would be a good idea to put a note inside stating the value of the original capacitor.
Start capacitors are pretty forgiving, as long as the motor starts good with the new capacitor it will be fine even though it's a little smaller. I wouldn't go much larger than the original.
If you do put in a different size of capacitor it would be a good idea to put a note inside stating the value of the original capacitor.
pattenp
Well-known member
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