Dynamic characteristic simulation and optimization for the energy-saving contactor with double coils

In the optimum design of contactors, it is important to analyze the dynamic behaviors. A new computational approach for analyzing dynamic characteristics of the energy-saving contactor with double coils was proposed. According to the contactor's unique characteristic that it has two transferable coils, the paper builds two different sets of equations. One describes the period before the switching position, and the other describes the period after the switching position. The equations deal with the electrical circuit, electromagnetic field and mechanical system considering the influence of friction. In addition, in order to make calculation easy, the equations introduce two specific transfer functions that can be calculated by using 3-D finite element method to convert the double coils into single coil. The validity of the proposed method is confirmed by experiment. Finally, the paper gives an optimum design for the switching position of the two coils. The optimum design reduces both of the first and the second bounce of the movable contact.