I was planning to pass this one on to Bjarney, since He can offer the most practical answers to Motor issues!
I agree also that component / Motor design is independent, making it a long shot to use a similar Motor's Capacitor
size (in ÂµF) and achieve proper operation.
The total Reactance in the Auxiliary winding needs to be rather tightly set, in order to achieve optimum performance
and highest Motor efficiency (the equipment's total efficacy).
I guess you could try a "hit/miss" approach with a run Capacitor, but if the Capacitor is too large, it might fry the aux.
Too large of a Capacitor (start or run) will cause an increasing load current plus an increasing backwards shift of the
reducing magnetic flux, as the Rotor speed increases.
This will suck as far as proper operation goes! (non-uniform torque, increased heat/wattage to overcome the odd flux
behavior, so on...).
too low of Capacitor value (too small) will make starting difficult, and a lag in overall torque + Motor efficiency (once
again, Motor efficacy is not met).
For Start Caps, too large would result in an overloaded start winding - both creating too much heat in the winding and
causing a non-uniform starting torque.
The increased current would be applied for a longer period of time, and easily result in a tripped OCPD
(well, only if certain devices are not being used
Too small of start Cap, and the Motor will struggle to start a heavy load, resulting in excessively long start circuit usage
- and a similar effect as the "too large" scenario!
Anyone object to this information? please feel free to chime in! We are all here to learn from each other, so please pass
on your knowledge.