Voltage sag: an overview of IEC and IEEE standards and application criteria

The establishment of of standards and guidelines to cope with power quality issues has become evident. Among these, voltage sags are the most important cause of interruption of industrial processes. Sag is heavily dependent on the supply systems configuration, process equipment design, systems switching and protection practices, among others. In this environment, the development and the proper use of standards to regulate custumers, equipment manufacturers and utilities relations regarding sags issues is a most important question. This paper presents a discussion on the IEEE and IEC power quality related standards, and their applicability to voltage sag evaluation in a industrial or commercial system, utility system, and to equipment.