Automatic power supply switching is a basic system affecting the reliability of power supply to consumers. The duration of its operation depends on the depth of voltage dips, the size and scope of disturbances in technological processes, the value of the motor starting current, and, consequently, the costs incurred. Due to the negative effects of improper switching of power supplies, the devices responsible for these functions must perform them in a fast, safe, and reliable manner. The requirements for such devices depend on the type of powered objects. The more complex the technology or process, the greater these requirements.