Partial discharges in micrometer voids in PTFE

In this work, a high bandwidth experimental setup is used to measure the inception voltage, the waveform and the apparent charge of partial discharges (PD) in artificial voids in solid insulating materials. The investigations include microvoids, i.e. voids with characteristics dimensions below 100 μm. In this paper, the results for PTFE (teflon) are presented. Several simplified models are used to estimate externally measurable PD quantities for given void geometries. A one-dimensional hydrodynamic model is used to obtain better insight into the relevant mechanisms and processes by comparison of measurements and simulation data. Experimental studies show that the measured values for the inception voltage correspond well with calculated inception voltage based on the critical streamer criterion. The hydrodynamic model provides a good qualitative description of the phenomena. The trends of externally measured correspond with those predicted by the authors´ models