Leakage current characteristics study on electrical equivalent circuit of field-aged RTV silicone rubber coated and noncoated insulators in a coastal area

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Abstract
As insulators play an important role in supporting power transmission and distribution system, ensuring their condition in order to keep working properly have become an unequivocally essential task to do. There are many ways that can be attained to monitor the state of insulators, which one of them is by observing the leakage current (LC) characteristics. Experiments of LC measurement on six field-aged RTV silicone rubber coated insulators and six noncoated insulators were conducted in a coastal area. Each measurement took place three times in a day, which are in the morning, afternoon, and evening in order to get different environmental conditions in terms of temperature and humidity. The LC waveforms obtained from the whole experiments were then analyzed, particularly the LC magnitude, Total Harmonic Distortion (THD), and dominant harmonics. Apart from the waveform itself, these parameters are equally important to obtain similar waveforms created through computer simulation on electrical equivalent circuit of outdoor insulator using ATP/EMTP software. There are six different LC waveforms consisting of coated and noncoated insulators varied in each three environmental conditions that are compared and discussed in this paper. It has been proven that the LC waveforms from the experiments can be developed as similar as possible by simulation using different electrical equivalent circuit parameters, such as capacitance, nonlinear resistance, and number of arc models with various switching parameters. Afterwards, the characteristics of the equivalent circuit are discussed and analyzed to distinguish coated and noncoated insulators' performance due to various environmental effects.