Short Electrical Treeing Introduction
"Amongst the most significant breakdown phenomena affecting high voltage solid insulation is electrical treeing. This involves the degradation of the insulation over time through the propagation of gas-filled channels branching out to create a distinctive tree-like shape within the material. Shortly following these channels bridging the insulation thickness, a full and destructive failure will occur.
Electrical trees can occur in both AC and DC systems, with the time to breakdown being dependent upon a number of factors including the magnitude and frequency of the applied voltage. Cables manufactured with defects such as voids or inclusions within the insulation may accelerate treeing leading to breakdown quickly after installation, compared to well manufactured systems which last for many decades before failure.
Great amounts of time and effort have gone into understanding this phenomenon, resulting in significant improvements in material design and manufacturing techniques ensuring long asset lifetimes. This research continues, at a fundamental level to determine the mechanisms behind tree initiation and propagation, to detect their growth and predict asset life expectancy, and to provide further preventative measures to slow their growth or to prevent them from being able to cause breakdown."