Field Validation Tests of the TLD Box for Online Power Transformer Winding Monitoring Systems

Condition monitoring of transformer windings has become a critical issue for proper asset management schemes in power systems. With the exception of on-load tap changers, transformer windings are the components most likely to fail, causing companies to incur heavy penalties. A new non-intrusive method for diagnosing the condition of transformer windings entitled "Transmission Line Diagnostics" (TLD) has been developed at UBC\´s research Lab and this paper details the results of validation tests done in the university\´s high voltage lab as well as at PowerTech\´s high voltage lab. The method is based on the characterization of the transformer as a long transmission line in the megahertz frequency range. The results show that the TLD method is just as sensitive as current leading methods used (FRA), and more immune to external influences.