How to calculate the single-phase motor start capacitor

 

Generally do not have to calculate the start capacitor is only played to a phase-shifting effect,and the starting coil with the coil emf phase shift Difference between each of the electrical angle of 180ºto produce a rotating magnetic field after the motor starts to cut off the start-up coil and capacitor,so the capacitance range of applications Wide general 550W-2200W motor with 450V200μf can start.

The rotation of AC motors rely on rotating magnetic field generated by the current. Three-phase motor flows through the phase difference of 120 degrees of phase current, can produce a rotating magnetic Field. 
Single-phase motor flow through the single-phase current can not produce a rotating magnetic field, the need to take some method to make it a rotating magnetic field, with capacitance is Method, is one of the most common method.The capacitor is used to phase separation, the current near 90º phase difference to produce a rotating magnetic field in the two Rao group. 
Three-phase electricity, each Current between the two-phase itself phase, without phase separation. The capacitor induction motor has two windings, a start winding and run winding. 
The two windings in space, a difference of 90 degrees. Start winding thread A larger capacity capacitor, when the run winding and start winding through the individual AC capacitor role in the start winding current in time than the running winding current ahead of the 90-degree angle before reaching the maximum. 
The formation of two identical pulse magnetic field, so that fixed in time and space The air gap between the child and the rotor of a rotating magnetic field, the role of the rotating magnetic field, the induced current in the motor rotor, the current and spin Turn the magnetic field interaction of the electromagnetic torque, the motor spin up. 
Single-phase motor capacitor formula: GC = 1950I/Ucos∮(micro-method) in which motor current, U: single-phase supply voltage, the cos∮: power factor,to take 0.75,1950: Constant Calculate the single-phase motor capacitor, starting capacitor capacitance of work 1-4 times.