软启动器的工作原理：
The working principle of soft starter:
软启动器是一种集电机软起动、软停车、
Soft starter is a kind of soft starting and soft stop for motor,
软启动器采用三相反并联晶闸管作为调压器，将其接入电源和电动机定子之间。这种电路如三相全控桥式整流电路。使用软启动器启动电动机时，晶闸管的输出电压逐渐增加，电动机逐渐加速，直到晶闸管全导通，电动机工作在额定电压的机械特性上，实现平滑启动，降低启动电流，避免启动过流跳闸。待电机达到额定转数时，启动过程结束，软启动器自动用旁路接触器取代已完成任务的晶闸管，为电动机正常运转提供额定电压，以降低晶闸管的热损耗，延长软启动器的使用寿命，提高其工作效率，又使电网避免了谐波污染。
The soft starter adopts three-phase anti parallel thyristor as voltage regulator, which is connected between the power supply and the motor stator. This circuit, such as three-phase full controlled bridge rectifier circuit. Start the motor using the soft starter, the thyristor output voltage increases, the motor accelerates gradually until the thyristor wholeconduction motor working in the mechanical properties of rated voltage, to achieve a smooth start, reduce the starting current, avoid starting over-current trip. When the motor reaches the rated speed, the startup process end, soft starter thyristor automatic bypass contactor with substituted completion pipe, provide the rated voltage of the normal operation of the motor, to reduce the heat loss of the thyristor soft starter, prolong the service life, improve the work efficiency, but also to avoid network harmonic pollution.
接线方法是要看软启动器的。一般有一拖一，一拖二，一拖多的也有，就是外围线路比较多了。接线图仅仅参考。
Wiring method is to see the soft starter. Generally there is a drag, a drag two, a drag more, there is more peripheral lines. Wiring diagram is only for reference.
