G. E. Vardakis

Electrical Treeing Propagation in Nanocomposites and the Role of Nanofillers: Simulationwith the Aid of Cellular Automata

Electrical Treeing Propagation in Nanocomposites and the Role of Nanofillers: Simulationwith the Aid of Cellular Automata In this paper the propagation of electrical treeing in nanodielectrics using the DIMET (Dielectric Inhomogeneity Model for Electrical Treeing) is studied. The DIMET is a model which simulates the growth of electrical treeing based on theory of Cellular Automata. Epoxy/glass nanocomposites are used as samples between a needle-plane electrode arrangement. The diameter of nanofillers is 100 nm. The electric treeing, which starts from the needle electrode, is examined. The treeing growth seems to be stopped by the nanofillers. The latter act as elementary barriers to the treeing propagation.

Electrical tree growth simulation in nanocomposite polymers: The role of nanoparticles and homocharges

The addition of nanometric size particles in a polymer matrix results in the creation of a polymer nanocomposite with different behavior and improved dielectric properties than the base polymer. In case of tree appearance in a polymer nanocomposite, the nanoparticles delay the tree propagation by changing its path. Except for nanoparticles, space charges, and particularly homocharges, play a significant role for the tree behavior. Treeing phenomena have been investigated using a simulation model, in order to evaluate the influence of nanoparticles and homocharges to tree propagation.

Electrical tree simulation and breakdown in nanocomposite polymers: The role of nanoparticles

Electrical treeing is a pre-breakdown mechanism, responsible for the long-term degradation of polymer insulation. In this study, the propagation of electrical tree in nanocomposite polymer has been investigated using D.I.M.E.T (Dielectric Inhomogeneity Model for Electrical Treeing), which simulates the growth of electrical tree based on Cellular Automata. It is demonstrated that a tree, which initiates from a high voltage electrode, delays to arrive at the opposite electrode causing breakdown, due to the nanoparticles. The latter seems to have a beneficial effect on both the propagation of electrical trees and the breakdown of the nanocomposite polymer.

Effect of nanoparticles loading on electrical tree propagation in polymer nanocomposites

The incorporation of nanoparticles into polymer materials is pivotal on electrical tree behavior, as nanoparticles seem to form barriers delaying and/or preventing tree growth. Even with a small nanoparticles loading, the polymer acquires great resistance to tree initiation and growth. In this paper, a cellular automaton model is used in order to investigate how different nanoparticles loadings affect tree growth in nanocomposites. Simulations are performed for dc voltage, which is applied to the needle of a needle-plane electrode arrangement. Epoxy/TiO2 nanocomposites with different nanoparticles loadings are used as samples. The simulation results show that tree growth is limited as nanoparticles loading increases. Moreover, the tree length depends on the nanoparticles loading and it is smaller in the epoxy/TiO2 nanocomposite with the higher nanoparticles loading.

Propagation of electrical tree growth in a composite solid insulation consisted of epoxy resin and mica sheets: Simulation with the aid of Cellular Automata

Electrical treeing is one of the principal factors affecting the insulating capability of solid insulation. Epoxy resin with mica sheets is used in machine insulation. In the present paper, a point-plane electrode arrangement was used in order to simulate the electrical tree propagation in such an insulating system. The mica sheets investigated were of comparable thickness with the epoxy resin. The simulation was performed with the aid of Cellular Automata (CA). Laplace equation has been solved setting appropriate boundary conditions at the interfaces between epoxy resin — mica sheet and epoxy resin — electrodes. The simulations were based on the local field variation, the local dielectric strength and also on the variation (even slight) of the dielectric constant of the insulating materials. Such local variations of the dielectric constants render possible local variations of the electrical field and, consequently, of the tree propagation. Mica sheets as barriers inside the main insulating material preventing the electrical tree growth. The thickness of mica sheets plays an important role in the propagation of trees. The simulations indicate that even in the case of a partial penetration of the mica sheets, no complete breakdown results. The applied voltage level plays also a crucial role in the resulting type of electrical tree. Higher applied voltages result in a bush-type tree, whereas lower applied voltages result in more pointed trees. The simulation results agree with experimental data.