High-frequency characterization and modeling of distribution transformers

Distribution transformers are generally assumed to block high frequency power line carrier signals and to require bypass networks where signals must cross a transformer. In this work, however, we show experimentally that significant coupling occurs at some frequencies both across distribution transformers and between different transformer phases in various commercial transformers. This suggests that the transformers may pass noise and coupled RF signals between low and medium voltage power lines much more readily than predicted by simple models. It also suggests that frequency adaptive or spread-spectrum methods should be able to communicate across distribution transformers without bypass networks. Measured results are applied to a commercial simulator model suitable for use within large simulations.