Clarification of Leakage Current Suppression Effect of Polymeric Insulators Applied for 6.6kV Distribution Lines under Rapid Contaminated Conditions

Tohoku Electric Power Co., Inc. is planning to apply polymeric insulators instead of porcelain insulators to improve reliability of 6.6kV distribution lines during heavy contaminated conditions. Distribution lines located in the coastal areas along the Sea of Japan often suffered tracking damage of covered wires from rapid salt contamination resulting in a large-scale power outage. Tracking of covered wires is caused by discharges derived from leakage current flowing on the contaminated insulators surface. To clarify leakage current suppression effect of the polymeric insulators applied for the distribution lines under rapid contaminated condition, salt water pouring tests of model high voltage lines and transformers were carried out using the same types of polymeric insulators. The resulting data confirmed that the polymeric insulators having hydrophobic surface suppress leakage current flowing over the contaminated surface and maintain appropriate insulation performance of the distribution lines.