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.
When the motor is started 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. The soft starter also provides soft stop function. The soft parking is opposite to the soft start process. The voltage decreases gradually and the revolution gradually drops to zero, avoiding the torque impact caused by free parking.
Working principle of soft starter -- starting mode
The soft starter is a kind of novel control equipment of motor soft start, soft stop, light load energy-saving and various protection functions in one of the domestic soft starter in peace hps2 series soft starter is most famous, and the main structure is connected in series between the power supply and the controlled motor three opposite parallel thyristor and its electronic control circuit. Soft starter generally have the following boot mode:
(1) constant current soft start of slope;
(2) ramp soft start up;
(3) step start;
(4) pulse shock starting.
Working principle of 3. soft starter
