A Technical Investigation of Voltage Sag

Voltage sag is regarded as one of the most harmful power quality disturbances due to its costly impact on sensitive loads. The vast majority of the problems occurring across the utility, transmission and industrial sides are voltage sags. The source of sag can be difficult to locate, since it occurs either inside or outside facilities. So, this paper analyses some aspects of voltage sag such as the cost of voltage sag, their characteristics, types of voltage sag, its occurrence, percentage of sag present in power system, acceptable level of voltage sag curve, voltage sag indices, its economical impact, ways to mitigate the voltage sag and finally few devices used to mitigate voltage sag.