How do you determine the capacitor rating of a start up capacitor in farads of an ac electric motor as per a swimming pool pump motor .
I can’t find a formula that gives you what the starter capacitor rating should be.
What is the relationship between capacitor rating and kilowatts.
The manufacturer defines that based on the coil winding characteristics etc. A good guess could be made by looking for a similar motor with the same HP and Wattage or Amps and use the run cap value from that. The chances should be good enough (but, technically incorrect) that the run cap from it will do.
Or, taker it to a local electic motor shop and they can measure the windings inductance etc and give a pretty good indication of the cap you need. They would probably do that all within the price of purchasing the cap from them.