Tree propagation and the effects of barriers

The authors describe impulse experiments using alternating voltages and the explosion effect simulated to create synthetic tree channels. It is confirmed that trees propagate by fast fracture triggered by the explosive effect of localized intrinsic breakdown at points of electrical stress concentration. The interaction between barriers and advancing tree channels is determined by the barrier´s adhesive bond to the surrounding matrix, its fracture toughness, and its melting point. Results are presented for various types of barrier cast in clear polyester resin