Single phase capacitor sizing

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.

This is basically a question of motor design.There is no straightforward regular relationship between capacitance and the motor size in kW.

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. read more

Motor start and run capacitor

Application of start and run capacitor for single phase motor.

Why we applied a capacitor for single phase induction motor?The reason is to improve performance of motor by generate the rotating field.Design for this motor have a two ( 2 ) stator winding,and one of it is the auxiliary and is connected by a suitable capacitor size.

The capacitor increases the starting torque and the full load power as the current flowing through the auxiliary winding, de-phased by the capacitor, creates a rotating field.The voltage across capacitor usually higher than the mains supply.

The choice of the capacitance is usually empirically made on the motor. This is because of shuttle differences between motor manufacturers.As the torque and the power of the motor also depends on the reactive power of the capacitor. read more