Electrical breakdown in transformers due to flow electrification

The authors describe physical modeling and experimental measurement techniques with well instrumented laboratory models that simulate physical processes at work in power transformers. Scenarios involving coupled interactions between electrical charging, chemistry, moisture, and temperature are being studied. In order to understand how these mechanisms can lead to transformer failure, well-controlled experimental facilities and sensors for continuous monitoring of charge density, oil conductivity, oil moisture, and temperature have been developed. Dielectrometry sensors for pressboard which can monitor pressboard conductivity and moisture distributions are also being developed. A Couette flow facility is used to experimentally model the flow regimes in transformers that are similar to pumps and plenums, primary flows through conduits, and secondary flows around spacer blocks, protuberances, and bends.