Tutorial on voltage sag analysis

Voltage sags are known as a serious problem causing mal-operation of equipment like computers, process controllers and adjustable-speed drives. In this tutorial various analysis techniques for voltage sags are introduced: characterization of individual sags from measurements as well as from theoretical calculations; stochastic assessment (prediction and monitoring); effect on equipment; and mitigation. Techniques are introduced for single-phase and for three-phase equipment. The state-of-the-art is presented as well as the theoretical background to understand and influence future developments.