Analysis and development of a ride-through device for ac contactors

Contactors with AC coils are among the most widely utilized electromechanical devices in industry. However, since this kind of equipment is usually very sensitive to disturbances in the utility voltages, they can be responsible for load misoperation and loss of production. This work presents an electronic device to protect AC contactors from power disturbances, such as voltage sags. Using the proposed system, it is possible to keep AC contactors operating continuously, even during voltage sags with residual voltages as low as 10% of the nominal system voltage or short-term interruptions.