What are the differences between frequency converters and soft starters?

Frequency converters and soft starters are two different electrical devices, and there are the following main differences between them.

Soft starters are mainly used to reduce the current impact when the motor starts and achieve smooth starting. It can gradually increase the conduction angle of the thyristor to make the motor starting current rise smoothly from zero to the set value, thereby avoiding the generation of impact current.

It is usually suitable for occasions where the starting torque requirement is not high, such as metallurgy, petrochemical, water pumps, air compressors, fans and other fields. In these fields, soft starters can protect equipment and reduce energy consumption.

Frequency converters can not only achieve soft starting, but also adjust the speed of the motor. The frequency converter starts the motor by changing the frequency, and can adjust the forward, braking, reverse and variable frequency operation of the motor.

It is suitable for occasions where precise speed regulation and control are required, such as machinery manufacturing, construction, pharmaceuticals, food and other industries. In these industries, frequency converters can meet the precise control requirements of motor speed and output power.

The soft starter introduces current closed-loop control to ensure that the motor maintains a constant current state during the starting process. It can be flexibly adjusted according to the load conditions and the characteristics of the grid relay protection, and the best starting current can be selected steplessly. The soft starter has a simple structure, is easy to maintain, has a small size, and is easy to install. Under light load conditions, the soft starter can intelligently sense the load state and reduce the motor terminal voltage in time, improve the power factor, and achieve energy saving effects.

The inverter has a wider range of functions, such as overload protection, multiple control modes, etc. It can achieve load starting without impact current, and maintain a relatively high power factor and output torque close to the rated torque during the entire starting process. The inverter has high control accuracy and can achieve more precise speed control. During the starting process, the motor current can not exceed the rated current of the motor, so there is no abnormal heating of the inverter, motor or other components.

The soft starter has a relatively low cost, is easy to install and debug, and does not require professional knowledge.

The inverter has a high cost, and the installation and debugging are relatively complex, requiring professional knowledge.