Functional features of soft starter

The soft starter is mainly composed of three pairs of anti-parallel thyristor voltage regulator circuits connected in series between the power supply and the controlled motor. Modern soft starters basically use power electronics technology and microcomputer control technology, with a single-chip microcomputer as the central controller control core to complete measurement and various control algorithms.

Therefore, the soft starter has strong functions and flexibility. The entire starting process is automatically controlled by digital program software. The electronic switch characteristics of three pairs of thyristors are used to control the trigger pulses through MCU or single-chip microcomputer to change the size of the trigger angle. Changing the size of the trigger conduction angle changes the conduction time of the thyristor, and finally changes the size of the three-phase voltage of the stator winding.

The soft starter has the following features:

1. Smooth start: The soft starter controls the voltage and current changes of the motor to achieve smooth acceleration start of the motor and avoid vibration and damage caused by excessive instantaneous current during the starting process.

2. Reduce starting current: When starting the motor, the motor current may reach three to five times the rated current, which may bring a high impact load. The soft starter reduces the starting current and extends the life of the motor by limiting the instantaneous jump of current.

3. Reduce starting noise: The motor is likely to generate a lot of noise when starting. The soft starter can gradually accelerate the motor to start, control the motor speed and acceleration, and reduce the noise during starting.

4. Reduce the starting power factor: When starting the motor, disturbing the power grid may cause voltage fluctuations. The soft starter can reduce the power factor at starting by controlling the voltage and current, thereby reducing the impact on the power grid.

5. Protect the motor: When abnormal conditions such as motor starting, overload, short circuit, etc. occur, the soft starter can initiate corresponding protection measures to avoid motor damage.

In summary, the soft starter can reduce the impact and damage when the motor starts, protect the life of the motor, and extend the service life of the equipment. It also reduces the power factor and noise during starting, and improves the safety and reliability of the equipment.

Functional features of ABB soft starter

1. Overload protection function: ABB soft starter introduces current control loop.

Therefore, the change of motor current can be tracked and detected at any time. By adding the setting of overload current and the inverse time control mode, the overload protection function is realized, so that 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 three-phase line current at any time. Once the current is interrupted, it can respond with phase loss protection.

3. Overheat 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 is automatically shut down and an alarm signal is issued.

4. Measuring loop parameters: When the motor is working, the detector in the soft starter monitors the motor's operating status and sends the monitored parameters to the CPU for processing. The CPU analyzes, stores and displays the monitored parameters. Therefore, the motor soft starter also has the function of measuring loop parameters.

5. Other functions: Through the combination of electronic circuits, various other interlocking protections can be realized in the system.