Tolerance Evaluating of AC Contactors to Irregular Sags With Differential Strategy

In industries, AC contactors (ACCs) are sensitive to voltage sags. Most existing tolerance evaluation of ACC to voltage sags are based on rectangular sags, which tends to overestimation in practice. To tackle the evaluation problem facing irregular voltage sags, this letter presents a differential strategy based method for ACC. The instantaneous waveform of arbitrary voltage sags is split into the superposition of short-term step signal series in time domain. The relationships of differential energy variation inside ACC are modeled, and differential variation of spring compression is concluded. ACC responses to irregular voltage sags are formulated by superposition of short-term step responses. Simulations and experiments show that the proposed method is able to precisely evaluate the tolerance of ACC, settle the evaluation problem to irregular voltage sags.