Capacitor Rating with Single Phase Motor

From what I understand, the run capacitor rating on a capacitor-run type single phase motor is determined using algebraic phasor calculations.

This has been covered by a previous post: http://cr4.globalspec.com/thread/15299/Power-factor-correction-capacitor-for-Single-Phase-and-FHP-motors

Normally power factor of capacitor start single phase motors is much improved. Any how, for calculating the desired capacitor, follow the link;

http://cr4.globalspec.com/thread/53635/How-to-Calculate-Capacitor-Required-to-Compensate-Given-KVAR

Capacitor provided in a single-phase motor is definitely not for imroving power factor, but to provide a split-phase to make the motor self-starting. It could be a Capacitor-start motor or a Permanent Capacitor Motor. Values of Capacitors will vary for Start Capacitor & Run capacitor.

The criteria for selection would be sufficient torque development only to over come the static inertia of the motor & the connected load.

One can refer to Electrical Machine Design by M.V. Deshpande.