Solving customer power quality problems due to voltage magnification

Reports by a Duke Power customer concerning equipment malfunctioning coincident with the switching of a 100 kV shunt capacitor bank led to field measurements and EMTP simulations to identify the possible sources of the problems and to find an economical solution. Measurements and simulation revealed the occurrence of voltage magnification at the customer’s site due to the effects of three different distribution capacitor banks on the feeder supplying the customer. A comparative evaluation of commercially-available capacitor-switching transient mitigation switching devices suggested the use of lowresistance pre-insertion inductors applied with circuit switchers to .,nergize the 100 kV capacitor k mk. Field measurements of capacitor-switching events after installation of pre-insertion inductors verified the elimination of voltage magnification and customer power quality problems.