The modeling of AC magnetic contactor for immunity studies and voltage sag assessment

This paper presents the parametric model of AC magnetic contactor to study behavior of contactor during voltage sags. The model derived from contactor structure and its operation so that electrical, magnetic and mechanical equations can be obtained. The model was simulated using electromagnetic transient program. The results show dynamic behavior and immunity of contactor during sag. Additionally, how the sag characteristics, such as point on wave, impact to contactor can study through the model. For voltage sag assessment, the voltage sag ride-through capability curves of AC contactor were constructed and field-test data were also applied. The model reveals that although sag does not cause contactor to disengage, it can cause decreasing in contactor operation lifetime.