New insulation structure for shell-form transformer

New insulation structure for shell-form transformers has been developed to optimize dielectric strength and cooling efficiency. Tapered joint of pressboard barriers in the oil/paper insulation structure enabled minimization of oil gap length and formation of uniform gap length between barriers, which greatly enhances dielectric strength of the barrier system. By use of nonwoven fiber elimination of leakage oil flow was realized in the insulation space. This not only improves cooling efficiency but also reduces static electrification by oil flow. Excellent improvement in dielectric strength as well as static electrification was confirmed by the test results of model transformers.