Evaluation in Laboratory of the Visual Corona and Electric Field Measurement Techniques to Inspect Polymeric Insulators

The paper presents the results obtained from the laboratory tests carried out to evaluate the visual corona and electric field measurement techniques for inspecting polymeric insulators on live lines. The evaluations were performed on different 115 kV polymeric insulators aged in a salt fog chamber. The results show that both large and small defects near the hot electrode can be detected by the visual corona technique, while large defects along the insulators may be found by the electric field measurement technique. Therefore, it is recommended that both techniques are applied to accomplish a better establishment of the state of polymeric insulators