Transients in Distribution System: Field Measurements

Transients are generated, whenever there is change in current flowing through inductor and voltage across a capacitor. In distribution network, thousands of switching operations are done daily, leading to voltage and current transients. This article covers transients observed during switching of capacitor, transformers and cables in a Utility network at Medium Voltage levels. Instead of relying on analytical simulations, measurements were made at site using special probes and high speed oscilloscope to capture the over voltages and currents during switching of different elements. For comparison purposes, measurements were made with switching done using SF6 and Vacuum Breakers.