"Three phase induction motor (ZDYR) with conical rotor soft start" is introduced in detail.

一、软启动设备的工作原理在三相电源与电机间串入三相反并联晶闸管（可控硅整流器），利用晶闸管移相控制原理，启动时电机端电压随晶闸管的导通角从零逐渐上升，电机转速逐渐增大，直至达到满足启动转矩的要求而结束启动过程，此时旁路接触器接通（避免电机在运行中对电网形成谐波污染，延长晶闸管寿命），电机进入稳态运行状态，停车时先切断旁路接触器，然后由软启动器内晶闸管导通角由大逐渐减小，使三相供电电压逐渐减小，电机转速由大逐渐减小到零，停车过程完成。启动时，使晶闸管的导通角从0开始，逐渐前移，电机的端电压从零开始，按照预设函数关系逐渐上升，直到达到满足启动转矩而是电动机顺利启动，再使电机全电压运行。从工作原理上看，软驱动器实际上是一个调压器，输出只改变电压，并没有改变频率。这一点与变频器不同。

The working principle, a soft start device in three-phase power supply and motor series three-phase anti parallel thyristor (SCR), using the principle of thyristor phase control tube, when starting the motor terminal voltage with thyristor conduction angle gradually increased from zero, the motor speed increases gradually, until meet the start torque requirements end start process, the bypass contactor is on (to avoid formation of motor harmonic pollution on the grid in the operation of the thyristor is prolonged life), a motor is in steady state, the first cut off the bypass contactor when parking, and then by the soft starter in the conduction angle of the thyristor is gradually reduced, the three-phase the power supply voltage decreases, the motor speed is gradually reduced to zero, the stopping process is completed. When starting, the thyristor conduction angle from the beginning of 0, will move to the motor terminal voltage from zero, according to the preset function gradually increased, until meet the starting torque but motor start smoothly and then make full voltage operation of motor. From the working principle, the soft drive is actually a voltage regulator, the output only changes the voltage, and does not change the frequency. This is different from the frequency converter.

二、软启动设备的优点

Two, the advantages of soft start equipment

1）起动时无冲击电流，通过逐渐增大晶闸管导通角，使起动电流从零线性上升至设定值；

1) no impulse current is started, and the turn-on angle of thyristor is gradually increased, the starting current is increased from zero to the set value;

2）属恒流起动，软起动器可引入电流闭环控制，使电动机在起动过程中保持恒流，确保电动机平稳起动；

2) is a constant current starting, soft starter can be introduced into the current closed-loop control, so that the motor in the starting process to maintain a constant current, to ensure the smooth start of the motor;

3）可根据负载情况及电网继电保护特性选择，能自由地无级调整至最佳的起动电流。

3) according to the load condition and the power system relay protection characteristic, it can freely adjust to the best starting current.

4）可以频繁的启动电动机，软启动允许10次／小时，而不致电动机过热。

4) can frequently start the motor, soft start to allow 10 times / hour, and not cause motor overheating.

（笼型电动机传统的减压起动方式有：Y-△起动、自耦减压起动、电抗器起动等，皆属于有级减压起动，其缺点是在起动过程中会出现二次冲击电流。）

(starting cage motor traditional decompression: Y- delta starting, start and self coupling decompression starting reactor, all belong to the class of starting the drawback is, in the process of starting impact current will appear two times.)