Capacitors in single phase motors 2

[Errol]

Is there any particular formula for determining the size of the starting and run capacitors of a single phase motor. I usually try to match the one being replaced - but now that I have some motors on the Shelf that I would like to use, I need to determine the sizes of capacitors required.

Also help me to convert some of my three phase motors to single phase. What size capacitor is required and what percentage of the motor rating (and speed) am I expected to achieve. I am working on a project and it is very expensive to bring three phase electricity - I intend to keep it single phase as long as I can.


Thanks Guys

 

[SteveKW]

Do a search on this site... there are a few that go into detail as what you need to do.

 

[jbartos]

Suggestion: Visit

http://www.electric-motors.co.nz/

etc. for more info
To calculate the capacitor capacitance value, it is necessary to know the single-phase motor electrical equivalent circuit parameters. Then, the added capacitor capacitance is supposed to cause a large enough phase displacement angle on the starting winding so that the motor can start.
To convert the three phase motors for the single phase power supply run via added capacitors, the single-phase motor starting intent can be followed. However, it is better to obtain a single phase to three-phase converter/motor drive to obtain better efficiency, motor operation and potentially the better motor life cycle.

 

[no2hypocrisy]

I guess there could be potential savings to be made by buying a fixed frequency (1-phase in, 3-phase out) inverter, if such a thing exists. I have worked with standard inverters, and wonder if there is a niche manufacturer for lower-cost fixed freq. inverter.