Characterization of Dielectric Walls of Capacitors

Dry-type High Voltage Capacitors

“…Due to a combination of technical and practical reasons, the final wound coil arrangement that was selected consisted of 5 µm-thick aluminum foils separated by a set of three dielectric layers made of ruggedized biaxially oriented polypropylene (PPR) each having a thickness of 12.7 µm. These layers were corona treated in order to increase their compatibility with the impregnating resin, which did not lead to any significant increase of the material dissipation factor that remained low (10 -4 ) [3]. This later material will be referred as PPRC.…”

“…This later material will be referred as PPRC. More details on this configuration was presented elsewhere [1,3]. Probably the most critical parts of the coils' assemblies are the coil-to-coil connections and the final two end-connection topologies.…”

“…Once the multi-coil or single-coil capacitor was assembled with the end-connectors, the assembly was then introduced into a suitable mold for thermosetting resin impregnation and curing process. For this purpose, a Vacuum Pressure Impregnation (VPI) technique [3,5] has been developed and the various processing parameters were optimized. The manufacturing process can be summarized in two main phases: the first one is carried out under vacuum and the second one under pressure.…”

“…Finally, after the completion of the curing process, a solid encapsulated capacitor is obtained. More details on the fabrication procedures are provided elsewhere [3] and will also lead to a future report.…”

“…Accordingly, there is an interest to find alternative encapsulating materials. One of the possible candidates is lowviscosity impregnating epoxy resin appropriate for Vacuum Pressure Impregnation (VPI) process, and prior reports have shown the potential of this technology [3,4]. 1 In order to evaluate the feasibility of dry-type capacitors with a rated voltage of 1.5 kV per coil (corresponding to about 40 kV/mm) an investigation was carried out on both the optimization of the processing parameters and the electrical performance of such capacitors.…”