motor starter capacitor

[zotdoc]

I have a 2 hp 1 phase 125vac motor for a dust collector, and it has a 125 vac 400 uF capacitor as a motor starter. Are motor start capacitors polarized? I want to hook this motor up and use it but the two wires are both black, so does it matter which wire is hooked to + or -?

[dacflyer]

no, motor caps are not polarized. you can go a higher working voltage if you cannot find the exact type, and it is possible to fudge just a little on the value of the cap too.
done it many times.

[Dean Huster]

Get a 240 replacement for the motor if you can -- you're having to repair it anyway. A 2hp, 120v motor draws around 20+ amps at full load. That's a lot of current and limits that circuit to one item. A similar 240v motor will only draw about 10-12 amps.

Dean

[Bob Scott]

What is the nominal capacitance value or range of a 120V motor start capacitor?
I've seen them sold with values of 12uF or less. Isn't 400uF a bit large?
Maybe I've just seen motor run capacitors. (?)

In my former house I installed a 36,000 BTU central A/C. There was an option for high torque starting of the compressor motor, which I assume consisted of a start capacitor. I didn't buy the option and I guess I didn't need it.

[zotdoc]

I would have liked to replace the motor with a 220 volt, but I don't want to spend the extra $$'s. I don't know what the usual capacitance ratings for motor starters are, but the one on the motor was a 400 uF. I bought one rated from 360-408 uF at a local electric supply store and the motor started right up and has worked well since. I was impressed at the apparent quality upgrade using "american made" equipment over the chinese junk that came with the motor. I hope I won't be buying a new 220 volt motor to replace the Harbor Freight dust collector motor but I guess I will be!