The soft starter is a novel motor control device that integrates soft start, soft stop, light-load, energy-saving, and multiple protection functions. Its main structure is a three-phase anti-parallel thyristor and its electronic control circuit connected in series between the power supply and the controlled motor. Different methods are used to control the conduction angle of the three-phase anti-parallel thyristor so that the input voltage of the controlled motor changes according to different requirements, and different functions can be realized.
High voltage soft starter
Low voltage soft starter
1. Overload protection function: The soft starter has introduced a current control loop, so it can track and detect the change of the motor current at any time. By increasing the setting of the overload current and the 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 make a phase loss protection response.
3. Overheating protection function: The temperature of the thyristor radiator is detected through 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. Other functions: Through the combination of electronic circuits, other kinds of interlocking protection can also be realized in the system.