A new compensation strategy for an AC contactor under voltage-sag events

This paper aims at researching the effects of voltage-sag events upon AC electromagnetic contactor (abbreviated as AC contactor) and developing a compensation strategy based on feedback control approach. An AC contactor model is first analyzed when sags event is ensured occurrence as well as a novel voltage compensation strategy is designed for timely offsetting the coil voltage; therefore, the critical equipment in continuous process industries are safely protected and prevents the loss caused by downtime. A dynamic performance evaluation was conducted on governing numerical model of an AC contactor for analyzing the system performance when the proposed compensation strategy is introduced. The simulation results clearly depicted that contactors are critical component as it is unable to ride through 20% sag and longer than 48 milliseconds. The effectiveness and feasibility of the proposed coil voltage compensation strategy during voltage sag events occur is validated by using simulation approach. Moreover, the shading rings have the effect of the contactor's transient performance when voltage sags event occur is studied and discussed as well.