Partial discharge analysis under hybrid AC/DC field stress

An important tool for investigating the reliability of high voltage insulation systems are partial discharge (PD) measurements. PD diagnostic at AC voltage is well known and approved, but on the detection and analysis under direct voltage (DC) condition less knowledge and experiences are available. Furthermore, in case of hybrid AC/DC voltage stress more detailed investigations are needed. Due to this lack of experience, as well as of appropriate models, this topic is an important field of study. Thus, partial discharge activity under hybrid AC/DC voltage stress is investigated. First results show that partial discharge behavior of insulators is different at hybrid AC/DC stress compared to pure AC and DC stress. The contribution presents calculation and measurements of the partial…