Three phase squirrel-cage asynchronous motor step-down starting four methods

Three-phase squirrel-cage asynchronous motor step-down starting methods are: the stator winding resistance ( Reactance) Starting; - Y — Delta step-down starting; Yanbian triangle step-down starting; Autotransformer step-down starting. Is the essence of the step-down starting, starting when reduce the voltage on the stator winding of the motor, to reduce the starting current. And then to restore the voltage rating, after starting motor into the normal working condition. The stator winding, series resistance ( Reactance) The stator resistance step-down automatic starting control circuit ( 一) For motor stator winding series resistance step-down starting control circuit automatically. Circuit working principle is: the power switch on the QS, press the start button SB1, electricity and self-locking KM1, series with the motor stator winding resistance R step-down starting, KT to electricity at the same time, after a delay the KT normally open contacts closed, KM2 will start to the main contact resistance R sub, motor into the normal operation of total pressure. Manual automatic mixing control line two, autotransformer step-down starting control circuitry autotransformer step-down starting refers to use autotransformer to reduce added when motor starting on the stator winding of the motor starting voltage. After waiting for motor starting, then autotransformer from, make the normal operation of motor under the pressure. Button, contactor control autotransformer step-down starting control circuit, star -- - — Triangle step-down starting control circuit star - — Triangle ( Y — Delta) Step-down start refers to the motor starting, the stator windings into a star, in order to reduce the starting voltage, reduce the starting current; After waiting for motor starting, and then change the stator winding into triangles, make the motor run full pressure. Y — Delta starter can only be used for normal run time for delta connection of the motor. Button, contactor control Y - Delta step-down starting control line in figure 2. 19 ( 一) For the button, contactor control Y - Delta step-down starting control circuit. Circuit working principle is: press the start button SB1, KM1, electricity and KM2, KM1 self-locking, star of the motor starting, when the motor speed close to the rated speed, press the SB2, KM2, KM3 to electric power and self-locking, motor run into triangle total pressure. Time relay control Y - Delta step-down starting control line in figure 2. 19 ( b) For the time relay automatic control Y - Delta step-down starting control circuit, the circuit principle of work is: press the start button SB1, KM1, electricity and KM2, star of the motor starting, KT also get electricity at the same time, after a delay time relay KT open normally closed contacts, make power KM2, normally open contacts closed, makes KM3 to close and self-locking, motor by star switch to normal operation of the triangle. Four, the triangle step-down starting control circuit of yanbian yanbian step-down start refers to the motor starting, the motor stator winding part of the 'delta' form, and the other part into 'Y' shape, make whole stator windings into yanbian triangle, after waiting for motor up, then switch to the stator winding of the 'delta' form total pressure.