What are Soft Starters? What is VFD?

Soft starters are used to limit load and torque during motor start up phase reducing material stress and wear of gearbox and other mechanical parts of power train. The speed setpoint is not adjustable.

Variable Frequency Drives give much more control over the motor as they are able to regulate acceleration/deceleration in closed feedback loop with immediate response from the encoders. The speed is controlled via PLC/other master system.

Soft starters are used to reduce and control the inrush current at the starting process of the motor. VFD is a speed control device that controls the speed of the motor from0 to the max RPM of the motor. VFD also have the inrush current protection but fixed to a certain percentage of the load or VFD output amperes whereas this is variable in soft starter. Also, soft starter doesn't have any speed control.

soft starter is used in A.C. electrical motors to temprorily reduce the load and torque.