Investigation of LC-Resonance Driving in Disconnector Bus-Transfer Testing

The ability to transfer load currents between parallel busbars is one of the main requirements for most disconnector switches in gas insulated as well as air insulated substations today. As such, the capability limits and testing methods are internationally standardized in IEC 62271-102. The test circuit dictated in this standard is the Thévenin equivalent of the high current, power frequency approximation of two parallel busbars supplied by an AC current source. This setup inevitably couples different factors influencing the bus-transfer switching process by directly specifying the pre-switching current through the disconnector switch and recovery voltage expected across it after successful switching. To facilitate a more detailed and direct investigation of bus-transfer switching processes, a different test method is suggested and consequently implemented as a proof of concept. The suggested method entails the use of an AC current source to drive a current through two parallel impedances representing different sections of a busbar. The disconnector switch under test is placed in series with one of the impedances. In order to analyze the feasibility of such a setup, a proof of concept current source along with two parallel impedances was built. The main design goal for the current source was to provide AC current