Electrical Conductivity Modeling and Fabrication of Carbon Nanotubes/Silicone Rubber Composites for High Voltage Insulators in Regions With a Polluted Atmosphere

Abstract

The condensation mechanism of the insulators’ surface, increase the surface electrical conductivity. The electrical conductivity of the insulator creates a high level of leakage current and causes the failure. Difference between the dew point and the surface temperature of the insulator which occur due to radiative cooling mechanism, is the major reason of the moisture condensation on the polluted insulator surface. To compensate for the temperature difference, carbon nanotubes (CNTs) are being added to the silicone rubber housing material. The main idea of this research is based on generating joule heating by reducing the surface resistance of high voltage insulators. For this purpose, a developed model based on Halpin–Tsai formulation for tensile modulus of nanocomposites is joined with the conventional power-law model for the effective electrical conductivity of silicone rubber matrix carbon nanotube composite (SMCNT). SMCNT samples are prepared with the addition of various CNT volume fractions to high temperature vulcanizing (HTV) silicone rubber by melt-blending method. The developed model reveals that the high fraction of thinner and longer CNT, thicker interphase, higher concentration of percolated CNT, lower waviness of CNT, and higher conductivity of CNT can make a higher effective conductivity for SMCNT.

Production and an advanced model for electrical conductivity of silicone rubber/carbon nanotube nanocomposites as outdoor insulator housing material

“…σ f , ρ, u and λ are the CNT conductivity, the tunneling resistivity of polymer, the CNT waviness, and the tunneling distance. CNT effective length (l eff ) is the shortest expanse between two tops of bent CNT representing a waviness factor as 10 u ¼ l l eff (10) By considering (9), σ tot can be predicted by…”

“…This temperature difference can be covered via changing the insulator housing material by applying conductive additives (such as CNT, carbon black, ZnO etc.). [6][7][8][9][10][11] Hence, a controlled leakage current is produced, which advances the temperature of the insulator and averts the condensation of moisture on the surface of the insulator. Use of RTV (room temperature vulcanizing) coatings with conductive additives for anti-icing applications has been reported in previous references.…”

“…[20][21][22][23][24][25][26][27] These noteworthy properties have attracted the scientists' attention to many applications such as crack development monitoring, 28 smart high-speed rail infrastructures, 29 electromagnetic shielding, 30 aerospace structural design, 31 shape memory materials, 32 and high-voltage insulators. 10 When the CNT concentration reaches a specified rate, called the percolation point, the electrical conductivity of polymer-CNT nanocomposite is considerably upgraded and the polymeric medium is transferred from an insulator to a conductive material because the CNTs can then create a threedimensional (3D) conduction network, simplifying electron transportation. 33,34 The large specific area and high density of CNTs normally result in the formation of a third phase called interphase areas.…”

Effect of fabrication method on the physical properties of carbon-nanotube/silicone-rubber nanocomposite in high-voltage insulators

“…11–18, authors studied the prediction and characterization of the icing phenomenon and the effect of icing on the leakage current. In reference 19, to cover the difference between the dew point and the surface temperature of the high-voltage insulator, carbon nanotubes (CNT) were added to the silicone rubber matrix and the influence of different factors of CNTs and the conductive network on the effective electrical conductivity of the nanocomposite was investigated. The vital feature of insulator housing material, is the hydrophobicity property which in case of any change in the housing material composition, must be retained.…”