Study of movement and stability of an injected air bubble in a uniaxially oriented polyethylene /oil insulation system under electric stress

A uniaxilly oriented polythylene (UOPE) tape has been developed by Brookhaven National Laboratory (BNL) in association with Batelle Columbus Laboratories. This tape is compatible with conventional cable oils and has good mechanical properties. Tests have been made on samples consisting of layers of this tape impregnated with dodecyl benzene oil with air bubbles injected into the insulation. The bubbles divided at the partial discharge inception stress and subdivided again when the stress was increased further, until they disappeared. The rate of disappearance depended on the electric stress applied and on the rate-of-rise of the stress.