ABSTRACT
The three most significant power quality concerns for most customers are: voltage sags; momentary interruptions; and sustained interruptions. Most residential customers are affected by sustained interruptions and momentary interruptions. This chapter addresses several types of power quality problems can occur, but these three are the most common; sags and momentary interruptions. Momentary interruptions primarily result from reclosers or reclosing circuit breakers attempting to clear temporary faults, first opening and then reclosing after a short delay. Fault location is the primary factor that determines the disturbance severity to customers. The number of momentary interruptions varies considerably from circuit to circuit and utility to utility. There is a difference between the reliability definition and the power quality definition of a momentary interruption. The power quality definition includes both operations of interrupting devices as well as very deep voltage sags. Voltage sags cause some of the most common and hard-to-solve power quality problems.
