The application of squirrel-cage asynchronous motor soft starter - working principle of the soft starter

Soft starter is a collection of soft start,soft stop,light load energy saving motor parts and multi-functional protection of motor control device.It not only realize no impact in the whole process of starting and smooth starting current,and according to the characteristics of the motor load to adjust the parameters in the process of starting,such as current limiting value,starting time,etc.In addition,it also has the protection of motor function,that is fundamentally solves the disadvantages of traditional step-down starting equipment.Soft starter used three opposite parallel thyristor as a voltage regulator,to wear it while plugged motor run capacitor into a power supply and the motor stator.

This circuit such as three-phase fully-controlled bridge rectifier circuit,main circuit diagram as shown in figure 1.When using the soft starter motor,the output of the thyristor voltage increase gradually,motor speed gradually,until the thyristor conduction,all motor electricalmotor1.blogspot.com working in the rated voltage on the mechanical properties of smooth start,reduce the starting current,avoid start over-current trip.For motor to achieve rated speed,the end of the boot process,the soft starter automatic bypass contactor to replace has completed the task of thyristor,provide the rated voltage for the motor magnet motor operation,to reduce the heat loss of thyristor,prolong the service life of the soft starter,improve the work efficiency,and make the power grid to avoid the harmonic pollution.Soft starter and also provide function of soft parking,soft parking,in contrast to the soft start process,voltage decreases gradually,speed gradually decreases to zero,to avoid the free parking torque caused by the impact.