Stability evaluation of an electromagnetic contactor during voltage sag

The objective of this paper aims at investigating the effects of the power disturbances, in particular, voltage sag upon the dynamic stability of an electromagnetic contactor. By using the basic definitions of passivity conditions or the energy-method, the dynamic stability of contactor can be easily identified by means of detecting the electrical-energy transferring direction during voltage sag. For performing the related qualitative analysis of the contactor, the numerical contactor model is first established based on the magnetic circuit analysis method. Several useful simulation results were conducted and shown that the dynamic stability of ac electromagnetic contactors was apt to be affected by voltage sag events. Finally, the proposed stability evaluation method for the contactor was ensured that it is feasible.