Evaluation on sensitivity of ac contactor during voltage sag

Ac contactor has been identified as one of the devices vulnerable to the effect voltage sag. We studied the performance of an ac contactor during voltage sags to identify its susceptibility level by determining its voltage sags ride through characteristics. An experiment was conducted to test the ride through capability of a typical contactor when subjected to voltage sags. From the experimental results, the ride-through capability curve is constructed to identify its susceptibility area. However it is important that the characteristics can be simulated without having to perform laboratory experiments so that a simulation of a system that has contactors can be carried for any type configurations. For that purpose, this paper presents the development of an ac contactor model using digital simulation software. The simulation results compared well with the curve obtained experimentally and thus validating the model to be used for any type of voltage sag simulation, which involves a contactor.