Effect of Internal Strain on the Lifetime of Filled Insulation

In this research work the effect of internal strain on electrical tree growth has been revealed in clear polyester. Strain was introduced in the specimen by the introduction of particles like aluminium oxide, polytetroflouroethylene (PTFE) and glass beads in a clear polyester resin C. Aluminium oxide particles of size 105μm, PTFE 675μm and glass beads of 1mm were tested. These materials were employed in a clear polyester resin thus making a barrier. The batch of 20 annealed, un-annealed and oiled specimens of each material were tested. Using aluminium oxide, PTFE and glass beads made detailed observation of the interaction between advancing tree channels and the particles. The clear interaction of tree channel between dense barrier of aluminium oxide and PTFE was impossible but glass beads being transparent in nature allowing progress of the tree through barrier to be carefully studied. Strain were removed or relaxed by annealing the specimens and work of adhesion reduced by oiling the specimens.