What is utilized in reduced-voltage starters for three-phase motors to change the potential difference?

In reduced-voltage starters for three-phase motors, autotransformers and resistors are commonly used to decrease the voltage applied to the motor during startup. This is pertinent because starting a large motor at full voltage can lead to excessive inrush current, which can damage the motor or the electrical system. By utilizing autotransformers, the voltage can be gradually increased as the motor reaches its operating speed, minimizing mechanical stress and electrical demand.

Resistors can also be included in the circuit to drop the voltage initially, thereby limiting current flow. The combination of these devices allows for a controlled start-up process that improves both the longevity of the motor and the efficiency of the electrical system.

While other devices like capacitors and inductors may have their own applications in motor control, they do not primarily serve the same purpose in the context of reduced-voltage starting as autotransformers and resistors do.