CHARACTERIZATION OF VOLTAGE SAGS EXPERIENCED BY 3-PHASE ADJUSTABLE-SPEED DRIVES

It is shown in this paper that voltage sags experienced by three-phase loads like adjustable-speed drives, can be classified into four types . Each sag can further be characterized by a magnitude and a phase-ang le jump. Relations between fault type, sag type, and load connection a re presented. The transfer of sags through transformers is discussed. Magnitude and phase-angle jump of sags are directly related to the vol tage in the faulted phase, or between the faulted phases, at the point -of-common coupling between the load and the fault.