What does a soft start do to the voltage supplied to the motor?

A soft start is a device used to control the acceleration of an electric motor by gradually increasing the voltage supplied to it during startup. This gradual increase in voltage helps to limit the inrush current, which can be several times higher than the motor's full-load current if the motor were to start directly across the line.

By slowly ramping up the voltage, the soft starter allows the motor to slowly pick up speed, reducing mechanical stress on both the motor and connected components. This is particularly important for applications where sudden starts could damage the motor or the machinery it drives.

This gradual approach contrasts with other methods that either apply full voltage immediately or maintain a constant voltage, which can lead to high starting currents and potential damage. Therefore, gradually increasing the voltage is the primary function of a soft start in managing mechanical and electrical stresses during motor startup.