Impulse testing of hybrid gas-solid polymer insulation systems

Paper in proceeding, 2013

Existing methods of impulse testing of high-voltage insulation are examined and their applicability to a hybrid gas-solid system is analysed. The experiments were conducted with spherical electrodes of different radii immersed in air and separated by a polymeric barrier. The obtained results are discussed in terms of test voltage patterns (withstand/flashover sequences) obtained with different test methods including standard and modified procedures. It is shown that presence of gas-solid interfaces in the considered system, which may be charged during testing with unipolar impulse voltages, makes correct determination of low probability flashover voltages needed for insulation design purposes hardly achievable due to statistical dependencies of the test results.