Monitoring of Dry Bands and Discharge Activities at the Surface of Textured Insulators with AC Clean Fog Test Conditions

Mohammed El Amine Slama,Oliver Cwikowski,Oliver Scopes,Abderrahmane Manu Haddad,Ronald T Waters,Maurizio Albano,Jon Knapper,Ibrahim Iddrissu

doi:10.3390/en14102914

Mohammed El Amine Slama, Oliver Cwikowski + Show 6 more

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https://doi.org/10.3390/en14102914

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Abstract

The aim of this study is the presentation of the results of an in-lab comparative study of electrical and thermal monitoring of artificially polluted, HTV-textured silicone rubber insulators, with different pollution levels. This work is a preliminary study of an in-situ monitoring of 400 kV SiR textured in a polluted environment. The results showed that the rms leakage current magnitude and pulses, and the average dissipated power depended on the pollution levels and the dry-bands formation. The discharge activity and their nature are governed by the pollution level and the voltage. A differentiation and a quantification between dry-band discharge onset and dry-band arc inception is highlighted.

Highlights

While the leakage current (LC) rose with the voltage, until approximatively 2 mA
This behavior continued with voltage increase, until step (3), corresponding to the first Dry Band Discharges (DbDs) activity
The maximum temperature at the insulator surface corresponding to dry bands (DBs) inception was close to 22.9 ◦ C, while it was around 32 ◦ C when the DBs extended

Summary

Introduction

The pollutant deposits covering the insulating surfaces can engender a considerable decrease of the dielectric strength of the systems, which can lead to FOVs. According to IEC 60815-1 [1], the FOV process is divided into six phases described separately below. Depending on the material properties used (ceramic/glass or polymeric), the FOV process of insulators is greatly affected by the insulator’s surface properties (hydrophilic or hydrophobic). In the case of glass and ceramic insulators, the surface is hydrophilic, while it is hydrophobic for polymeric insulators. The process of pollution FOV on hydrophilic surfaces begins with the deposition of a contaminant layer (containing salt, insolubles) at the insulator surface. The second phase of the process is the wetting of the contamination layer according to different mechanisms (fog, light rain, condensation)

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