Severity Indices for Assessment of Equipment Sensitivity to Voltage Sags and Short Interruptions

The paper proposes new indices to assess the impact of voltage sags and short interruptions on industrial equipment. The indices translate physical sag parameters into terms that reflect the severity of the disturbances as seen by the equipment. Based on actual tests performed with different types of equipment, the impact of voltage sags and short interruptions is described in terms of magnitude severity index (MSI), duration severity index (DSI), and combined magnitude duration severity index (MDSI). Using these indices, the uncertainties involved in equipment tolerance are addressed through proper event categorization and a common platform developed for the evaluation of equipment ride through capability with respect to voltage sags and short interruptions.