On Wed, 18 Jul 2018 13:18:42 -0700, wrote:

Any reason for not disclosing the motor model number? Yes, I know
it's 40 years old and Granger can't find it.

There are two caps in most such motors. One is the "starting
capacitor". The other is the "run capacitor".
https://www.youtube.com/watch?v=qsuzfz5qcIE
https://www.youtube.com/watch?v=OMd9QkinXz4
I'm fairly sure they should NOT be wired in parallel.

For 220VAC, the starting cap should be about 30 to 50uF/kW.
3HP(mechanical) = 2.2kW so try about 90uF.

The run cap is usually about 5 - 20uF.

For the starting capacitor calculations, see:
https://www.electricneutron.com/electric-motor/single-phase-capacitor-sizing/
https://www.quora.com/How-do-I-calculate-capacitor-value-for-single-phase-motor
Mo
https://www.google.com/search?q=calculate+motor+starting+capacitor

I couldn't find anything on calculating the run capacitor.


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Jeff Liebermann
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