Sizing motor capacitors

In the course of my scrounging, I often come across old fractional HP
electric motors with capacitors that have leaked out or for some other
reason are not working correctly. There is rarely any information on the
nameplate as to the value of the capacitor, and any value stamped on the
capacitor is usually long gone. Does anyone know of any rule of thumb or
formula for calculating the value of starting capacitors. Thanks Ron

Try this on "Recreational Crafts-metalworking" They talk about that stuff
allatime.

Ron Finet wrote:

In the course of my scrounging, I often come across old fractional HP
electric motors with capacitors that have leaked out or for some other
reason are not working correctly. There is rarely any information on the
nameplate as to the value of the capacitor, and any value stamped on the
capacitor is usually long gone. Does anyone know of any rule of thumb or
formula for calculating the value of starting capacitors. Thanks Ron

Try 40 to 50µF per horse power and use fractional amounts for motors
smaller than 1 hp. Funny that you ask this question right when I am in
the middle of trying to put together a static phase converter for a
lathe I have acquired.

Ron Finet wrote:

In the course of my scrounging, I often come across old fractional HP
electric motors with capacitors that have leaked out or for some other
reason are not working correctly. There is rarely any information on the
nameplate as to the value of the capacitor, and any value stamped on the
capacitor is usually long gone. Does anyone know of any rule of thumb or
formula for calculating the value of starting capacitors. Thanks Ron

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