IoT-Enabled Automatic Star-Delta Starter and Protection System for Three-Phase Induction Motors: Design, Implementation, and Future Prospects

Induction motors experience high inrush currents during startup, typically 8–10 times their rated current, due to the short-circuited nature of the rotor bars. This phenomenon can lead to excessive stress on the motor and associated equipment. To mitigate this, a reduced voltage starting mechanism is implemented using a star-delta starter, one of the most widely adopted methods in industrial applications for 50 Hz motors. This paper presents a low-voltage startup technique for induction motors integrated with a protection scheme. The motor is initially started in a star connection, where the line voltage is reduced by a factor of √3, thereby minimizing the inrush current. After the motor reaches a specified speed, the connection transitions to delta, applying the full-rated voltage for normal operation. The proposed methodology ensures a controlled startup, reduces electrical and mechanical stress, and enhances the overall efficiency and reliability of the motor system.