Experimental investigations on the behavior of decomposition gases in insulating liquids caused by partial discharge and breakdown

In this paper, the gassing behavior of insulating liquids under the influence of partial discharge (PD) stress and electric breakdown stress is presented. The investigations were performed on three of the most common insulating liquids: mineral based transformer oil, ester liquid, and silicon liquid. The gassing behavior of each of these liquids was examined concerning dissolved decomposition gases in the liquids as well as undissolved decomposition gases, which are caused by PD or lightning pulses. The amount and the composition of the gases were both analysed using gas chromatography. The experiments point out that the amount and composition of the dissolved and undissolved gases differ from each other