Power transformer diagnostics
Power transformer diagnostics involve assessing the condition of vital parts of power transformers, such as insulation, windings, core, bushings, and the tap changer. The scope of measurements is adjusted to the size and importance of the transformer, including failure analysis – transformer forensics, and dielectric response analysis. Beyond this standard scope, extended diagnostics include additional measurements such as Frequency Response Analysis (FRA), insulation system analysis using the RVM method, and dielectric response analysis (PDC & FDS methods).
When determining the causes and locations of faults or failures in transformers, special diagnostic methods are applied during on-site testing. These methods include ultrasonic diagnostics (partial discharges, thermal activities) and tap changer diagnostics.
With ultrasonic diagnostics, it is possible to locate partial discharges (PD), poor contacts, or localized overheating (> 200⁰C). This method allows for pinpointing potential sources of problems at the installation site, assessing the feasibility of onsite repairs, and evaluating the operational risks of problematic transformers.