The impact of nano-coating on surface charge accumulation of epoxy resin insulator: characteristic and mechanism

Abstract

The flashover phenomenon of the insulator is the main cause for insulating failure of GIS/ GIL, and one of the most critical impacting factors is the accumulation of surface charge. The common methods to restrain the surface charge accumulation are reviewed in this paper. Through the reasonable comparison and analysis of these methods, nano-coatings for the insulator were selected as a way to restrain the surface charge accumulation. Based on this, six nano-coated epoxy resin samples with different concentrations of P25-TiO 2 nanoparticles were produced. A high precision 3D surface charge measurement system was developed in this paper with a spatial resolution of 4.0 mm 2 and a charge resolution of 0.01 µC (m 2 • mV) −1 . The experimental results for the epoxy resin sample showed that with the concentration of nanoparticles of the coating material increasing, the surface charge density tended to first decrease and then increase. In the sample coated with 0.5% concentration of nanoparticles, the suppression effect is the optimum, leading to a 63.8% reduction of charge density under DC voltage. The application test for actual nano-coated GIS/GIL basin insulator indicated that the maximum suppression degree for the charge density under DC voltage could reach 48.3%, while it could reach 22.2% for switching impulse voltage and 12.5% for AC context. The control mechanism of nano-coatings on charge accumulation was proposed based on the analysis for surface morphology features and traps characteristics; the shallow traps dominate in the migration of charges while the deep traps operate on the charge accumulation. With the concentration of nanoparticles in nano-coating material mounting up, the density of shallow traps continuously increases, while for deep traps, it first decreases and then increases. For the sample with 0.5% concentration of nanoparticles coated, the competition between shallow traps and deep traps comes to the most balanced state, producing the most significant suppression impact on surface charge accumulation.

Molecular Dynamics Simulation and Experimental Studies on the Thermomechanical Properties of Epoxy Resin with Different Anhydride Curing Agents

“…It is widely used in high voltage insulation systems [1,2,3,4,5]. Composites prepared by filling modification are usually used to improve the thermomechanical properties of epoxy resins [6,7,8,9,10]. However, filling of a large number of fillers will lead to decreased insulation properties [11].…”

Dynamics of surface charge and electric field distributions on basin‐type insulator in GIS/GIL due to voltage polarity reversal

“…The electric field E can be calculated by potential φ : A large number of experimental results indicate that the significant leakage current can be observed on the insulator surface on the condition of HVDC, and its value has a great influence on the surface charge characteristics [19, 33–35]. The surface current J s is closely related to the surface conductivity γ s and the tangential electric field E t on the solid–insulating material surface [36] The surface conductivity γ s has an exponential relationship with the tangential field E t on the insulator surface [36, 37] where γ s0 is the basic conductivity and α is the correlation coefficient between surface conductivity and electric field.…”

“…A large number of experimental results indicate that the significant leakage current can be observed on the insulator surface on the condition of HVDC, and its value has a great influence on the surface charge characteristics [19,[33][34][35]. The surface current J s is closely related to the surface conductivity γ s and the tangential electric field E t on the solid-insulating material surface [36] J…”

Transition of the dominant charge accumulation mechanism at a Gas‐solid interface under DC voltage

“…The state of the insulator surface also has a large impact on surface conductivity. Recently, surface fluorination [36,37], low-temperature plasma treatment [27,28] and nano coating [26,38,39] have been introduced to treat the insulator surface to inhibit the surface charge accumulation, and the surface conductivity will fluctuate within a certain range after such treatments [14]. In this study, the surface conductivity is adjusted by changing the basic conductivity s0 .…”