A soft starter is a device used to temporarily reduce load and torque during motor startup.
A motor typically draws inrush current up to 10 times higher than their running current during startup, and up to 3 times higher torque. This kind of mechanical stress dramatically reduces the motor's service life, and the large power draw can propagate to other equipment in the system. Soft starters are designed to eliminate these undesired side effects of motor startup.
Soft starters reduce starting torque by temporarily reducing voltage or current input, allowing the motor to accelerate smoothly. Soft starters are also able to control motor deceleration, reverse motor direction, and provide overload protection. They are an ideal alternative to drives where a more cost-effective, simple solution is required.