A device for improving the immunity of ac contactors during voltage dips

Abstract

This paper describes an electronic device that enables AC contactors to ride through power quality disturbances. The proposed device is connected to the contactor coil and consists of a power conversion excitation and hold-in circuit, a control circuit, an immunity circuit and a shutdown circuit. It does not disturb contactor operation, is easy to use and can be built from cheap, commercially available components. Experimental tests have demonstrated the effectiveness of the proposed electronic device for improving the immunity of AC contactors during power quality disturbances, particularly voltage dips.