Analysis of electrical tree propagation through glass fiber barrier

In this paper, two sets of samples are examined, one for plain polyester resin and the other for glass fiber composite. In both sets, a pin to plane configuration is used to grow electrical trees around the barrier area. Several patterns of tree propagation are investigated. Due to the effect of barrier to hinder the growth, tree shape and growth rate are influenced at both sides of the barrier. The structure of barrier and its adhesion to the surrounding resin are the main factors to be considered for selection of the barrier to prolong the lifetime of composite. Horizontal growth relationship with penetration delay is studied. This delay is aggravated by the lack of energy of horizontally grown leading branches. A mechanism, explaining the delay of a leading branch to penetrate the barrier, is introduced. The mechanical stresses determined by de-bonding, deformation and carbonization in the interfacial area are studied. Finally, the results of this work are very important for breakdown analysis, life assessment and improvement of composite insulation and power cables.