How to sizing the starting capacitor?ġ) A rule of thumb has been developed over the years to help simplify this process. When replacing these capacitors, the capacitance value and voltage should be taken from the manufacturer’s plate on the motor or from the old capacitor.This must be correct within ±5% and is sometimes stipulated down to a fraction of a μF.The choice of a running capacitor is even more limited than with a starting capacitor.
This is basically a question of motor design.There is no straightforward regular relationship between capacitance and the motor size in kW. When install a motor using capacitor for starting or running methods,we must sizing the rated of capacitor suitable with motor to get correct starting torque and avoid winding from overheating and can cause a damage.
