Life prediction for transformer winding insulated with epoxy resin and thickness-reduced paper through voltage endurance tests

This paper investigates the epoxy resin coated paper-oil insulation between windings wires of a transmission power transformer. Voltage endurance test has been performed separately on the epoxy-resin layer and on the complete insulation. The test result reveals the voltage vs. lifetime characteristics of the epoxy resin layer, which further supports the life prediction on the complete insulation. The predicted lifetime ensures the reliability of the investigated insulation design and further suggests the possibility to reduce the thickness of the paper insulation layer.