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reza hajian
mohammad mirzaie


Porcelain Suspension Insulators are widely used in overhead transmission lines. During operation, the outdoor insulators are subjected to environmental stresses such as ambient humidity continually which may reduce their performances such as surface resistance. Under these conditions a large leakage current (LC) may flow on the surface and degradation may take place. In long term the degradation may lead to the flash over of the insulators and serious damages.
This paper describes an investigation on the leakage current harmonic components of standard and anti-fog porcelain insulator strings under humidity conditions. The insulator string samples were put in a test chamber with controlled humidity conditions. AC voltage with different levels and frequency of 50 Hz were applied. The tests were conducted in high voltage laboratory of Babol University of Technology and the LC waveforms were measured. Leakage current characteristics such as peak value, the harmonic content magnitudes and also the 5th to 3rd harmonic ratio in different voltages and humidity conditions were analyzed.

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