Canadian National Power Quality Survey: frequency of industrial and commercial voltage sags

In 1991, the Canadian Electrical Association (CEA) took a proactive approach to power quality problems and initiated a three year "Canadian National Power Quality Survey" involving twenty-two electric utilities. This paper presents the survey results of the frequency of voltage sags at industrial and commercial sites monitored at their utilization voltage levels (e.g., 120, 347 V) and on the utility primary side of their facilities and discuss the implications as to the origins of voltage sags. The paper also presents the total number of voltage sags at a given site and its correlation with the number of voltage sag incidents (i.e., one or more voltage sags occurring on one or more phases within a short time interval) and its implications for assessing the frequency of disruptions due to voltage sags at industrial and commercial sites.