Charge accumulation on slightly conductive barrier systems and its effect on breakdown voltage in an air insulated rod plane arrangement
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The barrier effect has been known since the 1930's. It is of great importance in the field of high voltage engineering as the breakdown voltage of an electrode arrangement can be increased significantly when dielectric barriers are applied. Nevertheless, an exact and general valid physical model explaining the barrier effect in gaseous, liquid and solid insulation systems is still not known. For gaseous insulation systems, the Marx-Roser model is widely accepted for explaining the barrier effect. The Marx-Roser model explains the barrier effect by a redistribution of the electric field in the gap. This redistribution is due to the space-charge field in front the tip but also due to the surface charge field formed on the barrier. This leads to a higher breakdown voltage of the system. In a recent publication of the authors, it was shown that the surface resistance of the barrier has a huge impact of the breakdown performance of the barrier arrangement. The breakdown voltage of the system decreased when the surface resistance of the barrier was decreased over a value of around 107 Ohm. To investigate this effect, the surface potential due to accumulated surface charges on the barrier surface was measured for three different values of barrier surface resistance. It was shown in the experiments that at lower values of surface resistance, less surface charges are accumulated at the barrier surface. This leads to a decrease of the field reduction effect between high voltage electrode and barrier surface and might result in lower breakdown values of the system.