Frequency-sensitive resistor started wound rotor asynchronous motor automatic commutation circuit

As shown in the figure, when the forward start button STF is pressed, the KMF coil is powered on and the motor is started by connecting the frequency-sensitive resistor in series. At the same time, the time relay KT starts timing. When the lKT setting time arrives, its normally open and instantaneous closing contacts act, and the contactor KM is powered to attract and protect itself, and at the same time the KT coil circuit is cut off. The main contact of KM will short-circuit L, and the motor will enter full voltage operation. Press STP to stop the motor. The operating principle of reverse operation is the same as above.