Performance verification of instruments adopted for voltage dip measurement

The Voltage magnitude reductions (dips or sags) are one of power quality issues with the greater economical impact. For this reason, often, supply sites are characterized by dip measurement campaign in order to asses the presence and the severity level of this kind of phenomena. This measurement results are important parameters for selecting equipment with proper intrinsic immunity. However, instruments devoted to dip measurement still present unresolved technical and theoretical issues related to the performance characterization. After a description of algorithms used for detection of voltage dips in agreement with standards, this paper presents, in simplified conditions, the systematic deviations that these approaches involve in event characterization. The obtained results are used during the experimental verification of the measurement accuracy of a commercial power quality instrument to asses its performance accounting the systematic deviations due to detection algorithm imposed by standard.