Abstract: Operation coil drive device of electromagnetic contactor includes current detector and drive controller. The detector, when switching control is performed on operation coils of the contactor, detects coil current flowing through the coils. The controller controls an on/off time ratio of a semiconductor switching element wherein the on/off time ratio during close circuit control becomes larger than the on/off time ratio during holding control. Power supply voltage is switchingly applied to the coils at the on/off time ratio. The controller includes a determination locus setter and a close circuit state determiner. The setter sets a determination locus that continuously increases along a change locus of detected coil current during close circuit control. The determiner determines a contact point close circuit state by contact of a movable contact to a fixed contact based on deviation between the determination locus by the setter and the detected coil current detected.

Abstract: Operation coil drive device of electromagnetic contactor includes current detector and drive controller. The detector, when switching control is performed on operation coils of the contactor, detects coil current flowing through the coils. The controller controls an on/off time ratio of a semiconductor switching element wherein the on/off time ratio during close circuit control becomes larger than the on/off time ratio during holding control. Power supply voltage is switchingly applied to the coils at the on/off time ratio. The controller includes a determination locus setter and a close circuit state determiner. The setter sets a determination locus that continuously increases along a change locus of detected coil current during close circuit control. The determiner determines a contact point close circuit state by contact of a movable contact to a fixed contact based on deviation between the determination locus by the setter and the detected coil current detected.