Voltage sag is one of the serious problems of power quality

which would cause severe impact on sensitive equipment such as alternating current(AC)contactors. In addition to voltage sag amplitude and duration which will affect the normal operation of AC contactors

the characteristics such as point-on-wave of sag initiation

sag phase jump also have significant impact on the switching of AC contactors. This paper makes a mechanism analysis of the impact of voltage sag on the AC contactor and builds a simulation model of the sag for analyzing the impact of point-on-wave of sag initiation and phase jump on the flux variation and switching of the AC contactor. Then eight AC contactors from mainstream manufacturers are studied and test results consistent with the results of the mechanism analysis are obtained. Finally

the AC contactor's tolerance curves with different voltage sag characteristics of point-on-wave of sag initiation and the phase jump are plotted

which can provide basic data for the AC contactor to deal with the problem of voltage sag and reduce the corresponding economic loss.