The soft starter uses three opposite parallel thyristors as the voltage regulator, which is connected between the power supply and the motor stator. This kind of circuit is like a three-phase fully controlled bridge rectifier circuit. When a 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 conductive and the motor operates at the mechanical characteristics of the rated voltage to achieve smooth operation. Start, reduce the starting current to avoid starting over-current tripping. When the motor reaches the rated revolution, the starting 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, thereby reducing the heat loss of the thyristor and extending the service life of the soft starter. , improve its working efficiency, and prevent the power grid from harmonic pollution. The soft starter also provides a soft stop function. The soft stop process is opposite to the soft start process. The voltage gradually decreases and the number of revolutions gradually drops to zero to avoid the torque impact caused by free stop.
Bypass type: When the motor reaches the rated speed, the bypass contactor is used to replace the soft starter that has completed the task, reducing the heat loss of the thyristor and improving its working efficiency. You can also use one soft starter to start multiple motors.
Non-bypass type: The thyristor is in a fully conductive state, the motor operates at full voltage, and the voltage harmonic component is ignored. It is often used for motors that work repeatedly for a short period of time.
Energy-saving type: When the motor load is light, the soft starter automatically reduces the voltage applied to the motor stator, reduces the motor current excitation component, and improves the motor power factor.
The soft starter uses patented technology for torque control when starting. Torque ramps up faster and losses are lower. It has a comprehensive protection function for the motor and soft starter. It can continuously detect the motor current at all times and provide reliable and complete protection for the motor. This protection function can still work after the bypass is started, which is not available in other soft starters. .
Alt48 calculates the power of the stator and rotor in real time while maintaining the acceleration torque. The motor power factor and stator loss are continuously calculated throughout the acceleration cycle. The power factor is calculated by detecting voltage and current, and the stator loss is deducted to obtain the actual rotor power and motor torque.
1) After using a soft starter, the starting current is significantly reduced, reducing power distribution capacity and investment in capacity expansion.
(2) The soft starter achieves smooth start without impact on the motor, improving the reliability of the motor.
(3) The soft stop method is used to reduce the impact on the machinery, extending the equipment and its The service life of related equipment.