Voltage sag

A voltage sag (U.S. English) or voltage dip[1] (British English) is a short-duration reduction in the voltage of an electric power distribution system. It can be caused by high current demand such as inrush current (starting of electric motors, transformers, heaters, power supplies) or fault current (overload or short circuit) elsewhere on the system.[2]

Voltage sags are defined by their magnitude or depth, and duration.[3] A voltage sag happens when the RMS voltage decreases between 10 and 90 percent of nominal voltage for one-half cycle to one minute.[2][4] Some references define the duration of a sag for a period of 0.5 cycle to a few seconds,[5][6] and a longer duration of low voltage would be called a sustained sag.[5] The definition of voltage sag can be found in IEEE 1159, 3.1.73 as "A variation of the RMS value of the voltage from nominal voltage for a time greater than 0.5 cycles of the power frequency but less than or equal to 1 minute. Usually further described using a modifier indicating the magnitude of a voltage variation (e.g. sag, swell, or interruption) and possibly a modifier indicating the duration of the variation (e.g., instantaneous, momentary, or temporary)."[3]

  1. ^ "IEEE 493-2007 - IEEE Recommended Practice for the Design of Reliable Industrial and Commercial Power Systems". The IEEE Standards Association. 2007-02-12. Archived from the original on March 25, 2022. Retrieved 2018-01-09.
  2. ^ a b Bollen, Math H.J. (1999). Solving power quality problems: voltage sags and interruptions. New York: IEEE Press. p. 139. ISBN 978-0-7803-4713-7.
  3. ^ a b Cite error: The named reference Karady was invoked but never defined (see the help page).
  4. ^ "Industrial Voltage Regulator Power Conditioner". Utility Systems Technologies. Retrieved 25 September 2013.
  5. ^ a b Vijayaraghavan, G, Mark Brown, and Malcolm Barnes (2004). Practical grounding, bonding, shielding and surge protection. Oxford: Newnes. p. 134. ISBN 978-0-08-048018-3.{{cite book}}: CS1 maint: multiple names: authors list (link)
  6. ^ Remus Teodorescu; Marco Liserre; Pedro Rodríguez (2011). Grid Converters for Photovoltaic and Wind Power Systems. Wiley-IEEE Press. ISBN 978-1-119-95720-1.