An overview of the：

Starter (also known as soft starter, motor soft starter) Soft starter is a novel motor control device that integrates motor soft start, soft stop, light load energy saving and multiple protection functions. It is called Soft Starter abroad. Its main composition is a three-phase parallel thyristor and its electronic control circuit connected in series between the power supply and the controlled motor. Using different methods to control the conduction angle of the three-phase parallel thyristor, the input voltage of the controlled motor can be changed according to different requirements, and different functions can be realized.

working principle of the soft starter:

Soft starter (soft starter) is a novel motor control device that integrates motor soft start, soft stop, light load energy saving and multiple protection functions. It is called Soft Starter abroad. The soft starter uses a three-phase parallel thyristor as a voltage regulator, which is connected between the power supply and the motor stator. Such a circuit is a three-phase fully controlled bridge rectifier circuit. When the soft starter is used to start the motor, the output voltage of the thyristor gradually increases, and the motor gradually accelerates until the thyristor is fully turned on, and the motor works on the mechanical characteristics of the rated voltage·to achieve smooth starting, reduce the starting current, and avoid starting over-current tripping. When the motor reaches the rated number of revolutions, the start-up process ends, and the soft starter automatically replaces the thyristor that has completed the task with a bypass contactor to provide the rated voltage for the normal operation of the motor, so as to reduce the heat loss of the thyristor and extend the service life of the soft starter , Improve its work efficiency, and make the grid avoid harmonic pollution. The soft starter also provides a soft stop function. The soft stop is the opposite of the soft start process. The voltage gradually decreases and the number of revolutions gradually drops to zero to avoid the torque impact caused by the free stop.

Protective function：

(1) Overload protection function: The soft starter introduces a current control loop, so it can track and detect changes in the motor current at any time. By increasing the setting of overload current and inverse time control mode, the overload protection function is realized. When the motor is overloaded, the thyristor is turned off and an alarm signal is issued. (2) Phase loss protection function: When working, the soft starter detects the changes of the three-phase line current at any time, and once the current is cut off, it can be used to provide a phase loss protection response.
(3) Overheating protection function: The temperature of the thyristor radiator is detected by the internal thermal relay of the soft starter. Once the radiator temperature exceeds the allowable value, the thyristor will be automatically turned off and an alarm signal will be issued.
(4) Its function, through the combination of electronic circuits, also realizes other kinds of interlocking protection in the system.