Single phase motor

You can choose One Third of Horse Power rating of motor as thumb rule.Otherwise you indicate the power factor of Motor for improvement.we will tell you rating of capacitor.

I need to know if the motor is a Permanent Split Capacitor motor (PSC) usually used for low starting torque applications such as fans. Start winding is always connected in parallel with the run winding through a capacitor, start with 5 micro farads for motors of fractional horsepower. Larger capacitors produce greater starting torque, however the motor will draw greater current, and run hotter,m suggest use of smallest capacitor that will produce adequate starting torque.

Capacitor start motors have start winding switches, some centrifugally operated by flyweights on non drive end, (Most Common), or a current relay, the coil of which is in series with the run winding, and drops out at about 2/3 rated motor current. Either switch connects the start winding through a capacitor only during start. Again capacitor size (Micro farads) determines starting torque, typically capacitors for capacitor start motors start at about 100 micro farads for fractional horsepower motors. Start Capacitors operate for only a short time during the start of the motor, and therefore heat very quickly i f energized for more than a few seconds.

Capacitor start motors are capable of producing very high starting torque proportional to the size of the capacitor, several hundred micro farads are common depending on the start torque required. The trade off is that the start inrush current also increases with start torque.

The voltage rating of the capacitor must be equal to or exceed the motor line voltage.

Hope this helps CEKM