Effects of Zinc Oxide Barriers on Electrical Tree Growth in Solid Insulation

The effect of zinc oxide (ZnO) on tree growth has been extensively investigated in this paper. The fillers are widely added in the insulation partly for reinforcement and also for suppression of tree initiation and their growth. The addition of zinc oxide (ZnO) as a filler into polymer insulation material also shows a non linear effect in dc conductivity when volume fraction of filler is above a certain level. In this work, zinc oxide (ZnO) employed in clear polyester resin as a barrier. High voltage 28kV rms is applied in the form of burst. The growth and nature of tree monitor on polariscope on regular interval. The life time of the specimen was filled with ZnO and ZnO as a barrier, is increased many fold. The results zinc oxide (ZnO) specimens are compared with Aluminium Oxide (Al O) barrier. In the case of Aluminium oxide (Al O) when tree was blocked by the 2 3 2 3 barrier, the branches of the tree become wider because of discharge activity and no such activity was found in the case of zinc oxide (ZnO). Ten specimens of zinc oxide (ZnO) barrier were tested and none of them breakdown.