Effects of transformer aged oil on electrification in a Couette flow

Summary form only given, as follows. Electrification, which occurs in transformers due to the entertainment of electrical double layer charge from the recirculatory flow of the oil over internal insulating pressboard surfaces, is simulated in an apparatus consisting of two coaxial cylinders. Pressboard covers these cylinders, while oil fills the gap between them. The inner cylinder is rotated which results in a turbulent flow in the oil region and measurements such as oil charge density, inner to outer open circuit cylinder potential difference, and inner to outer cylinder short circuit current are taken. Comparisons are made between fresh and aged oil for various transient and constant flow rates, temperatures, moisture levels, and applied AC/DC voltage stresses