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3 hp motor capacitor puzzle

keith7218

Plastic
Joined
Dec 26, 2019
Hello I have a 3 hp electric motor with no meaningful identification markings. I appears to be original to a 1989 Swan 203 air compressor.

The motor has 6 wires coming out:
2 heavier gauge red wires marked 1, and 7
2 yellow wires one marked 6 other unmarked
2 blue wires unmarked coming from the centrifugal switch

there is an interrupter switch as well 2 black wires

2 capacitors:
one appears original with unreadable markings tests out at 740uf
other appears newer marked as 708-850uf 110/125v tests at 790uf.


My question is can a motor like this have 2 capacitors the same value or must the run capacitor be of a lower value? Also the correct way to wire it? thanks in advance for any thought you make put into this
 
Since info is a bit lacking in your post, some general questions to help us.
Have you ever had this running? or when you got it, it was it apart?
No info on wires (if any) that went to the capacitor box.
How do you know it is 3 HP when there are no markings?
Both capacitors are for starting.

Posting some photos of what you have may help us.

Bill
 
Since info is a bit lacking in your post, some general questions to help us.
Have you ever had this running? or when you got it, it was it apart?
No info on wires (if any) that went to the capacitor box.
How do you know it is 3 HP when there are no markings?
Both capacitors are for starting.

Posting some photos of what you have may help us.

Bill

Hello thanks for your reply. Never running. Pic of capacitor box as I got it.
It seems all wires run into the cap box. Notice one cap fits in nicely while other does not.
[/ATTACH]20191226_181356.jpg20191226_181446.jpg20191226_181906.jpg
Only info on hp size is application. 203 Swan compressor. Paint seems to be matching but cant be 100%.
The blue wires are both run to a centrifugal switch which I assumed disengages at rpm.
I hope these pics help, I have far more time invested than what its worth but I cant seem to give up on it
 
The size of the motor (as much as I can assess it based on the photos) fits 1/3HP-1HP more than 3HP. We know that Asian horses are smaller. :) But I may be mistaken, of course.

They might use the second capacitor because they didn't have one with needed values handy, or they had one that was too large to fit in. I would tend to think those capacitors were connected in series to increase their voltage rating and drop the total capacitance. Ballpark values for a starting capacitor will be around 300-400µF for motors around 1/2HP-3/4HP and about 500-600µF for 1HP-3HP motors.
 
What makes you think that one of your capacitors is a run capacitor?

The capacitor without the connect screw mounts is kaput. The other one probably isn't far behind.
 








 
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