Test setup and methods for the electrical characterization of semiconducting powders

In insulation system of high voltage rotating machines, different insulating tapes consisting of mica, resin and glass cloth carrier were used. In the winding head, where the generator bar leaves the slot, the electric field has to be graded through the so-called end winding tapes. Ideally, these tapes present a nonlinear characteristic. For this reason, semiconducting fillers were added into the polymer matrix during the tapes production process. One important aspect of this study was the electrical characterization of semiconducting powders. Therefore, a test setup was constructed and different measurement methods were compared. The challenge of the construction was the performance and durability at high temperatures (class F), whereby only heat resistant materials for the test cell and…