Leakage current monitoring for silane epoxy resin insulator under tropical climate conditions

Polymer outdoor insulators have been developed and used on transmission lines and power distribution network. A polymeric insulating material that is widely used is epoxy resin and silicone rubber. Each material has its own advantages and disadvantages. Generally, polymeric materials have dielectric properties better than the ceramic, glass and porcelain materials. The dominant factors affecting performance of outdoor insulators are like temperature, rain, humidity, ultraviolet rays, condensation and contaminant. As a results, the insulator surface will be easily contaminated and flow current. For a long time, these events can cause damage to the surface of the insulator and finally cause flashover. To improve the surface properties of materials, silicon rubber material that has the ability to repel water were added. Silica sand was mixed with silicon rubber to improve the mechanical properties. In this paper, the influence of tropical climate conditions such as temperature, humidity, wet and dry conditions on leakage current characteristic of 20 kV outdoor insulators with silane epoxy resin has been investigated. The test was conducted on laboratory with AC high voltage 50 Hz and range of temperature from 30^oC to 60^oC and range of humidity from 40% RH to 70% RH were applied to the insulators. The chamber was used to placing the insulator. The monitoring results showed that the leakage currents on insulator surface were affected by temperature and humidity. A minimum leakage current occurs at 40% RH and a maximum current occurs at 70% RH. Meanwhile, the influence of the ambient temperature at leakage current is less significant because it ignores the factor of air pressure and humidity.