A Novel Breaking Strategy for Electrical Endurance Extension of Electromagnetic Alternating Current Contactors

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The electrical endurance of an electromagnetic alternating current (ac) contactor can be reflected by the mass loss of its contacts during operations. This paper carries out ac contactor endurance tests in which arcing phase angles (APAs) are fixed. Contact mass losses are measured, and the electrical signals of the contactor circuit are acquired. Thus, the corresponding energies of each break process are computed. This paper investigates the relation of arcing phases, arcing energies, and mass losses of break processes, and concludes that the higher arcing energies cause greater contact mass losses. Then, this paper proposes a breaking strategy that controls the APAs to minimize and balance the contact mass losses of the three phases of an ac contactor. Therefore, the erosion on each contact is reduced and the total operation number can be increased. Compared with random breaking, the novel strategy significantly improves the electrical lifetime of the ac contactors.