Correlation of partial discharge and dissolved gas analysis results from discharge activity in SRBP

The use of appropriate condition assessment criteria for the continued service of synthetic resin bonded paper (SRBP) based insulation is necessary for the continued operation or lifetime extension of SRBP based HV plant. Here, we report on work undertaken to investigate quantitatively the relationship between partial discharge activity occurring within the SRBP core with the production/absorption of decomposition gas in the surrounding oil. The emphasis of the results was to look at gases typically observed in transformers and associated bushings and their rate of production. Gas production rates considered here include H₂, CO, CH₄, C₂H₂, C₂H₄, and C₂H₆. Constant stress ac tests were conducted on pin-plane geometry SRBP samples, which were immersed in transformer oil. During each test, the partial discharge activity over the duration of the tests was monitored and complemented by periodic sampling of the surrounding oil for dissolved gas analysis (DGA). Prior to the experiments, the SRBP samples were conditioned to produce varying amounts of absorbed oil and moisture absorption. The results of DGA on the oil, including the variation of gas evolution as a function of partial discharge activity, and chemical status (i.e. amount of oil/moisture) are discussed.