Statistical Analysis of Partial Discharge during Electrical Tree in Silicone Rubber Nanocomposites under Elevated Temperature

The electric fields at the cable accessories such as jointing and termination are not uniform due to the nonuniformity structures of the accessories. Thus, it has attracted the formation of the electrical tree inside the cable accessory that is commonly made from silicone rubber. Also, the location of the cable that is exposed to the high temperature level gives severe effect to the electrical performance of the insulation. Recently, the inclusion of nanoparticles into the cable insulation has resulted in a promising outcome by resisting the discharge phenomenon such as treeing. However, the study on partial discharge during electrical trees grown in silicone rubber nanocomposites under elevated temperature is scarce including the statistical analysis of the partial discharge mechanisms. Therefore, this chapter is aiming to analyze the statistical behaviors of partial discharge during electrical tree growth in silicone rubber nanocomposites under the effect of temperature

Identifying Prognostic Indicators for Electrical Treeing in Solid Insulation through PD Analysis

This paper presents early results from an experimental study of electrical treeing on commercially available pre-formed silicone samples. A needle-plane test arrangement was set up using hypodermic needles. Partial discharge (PD) data was captured using both the IEC 60270 electrical method and radio frequency (RF) sensors, and visual observations are made using a digital microscope. Features of the PD plot that corresponded to electrical tree growth were assessed, evaluating the similarities and differences of both PD measurement techniques. Three univariate phase distributions were extracted from the partial discharge phase-resolved (PRPD) plot and the first four statistical moments were determined. The implications for automated lifetime prediction of insulation samples due to electrical tree development are discussed

Identifying Prognostic Indicators for Electrical Treeing in Solid Insulation through PD Analysis

This paper presents early results from an experimental study of electrical treeing on commercially available pre-formed silicone samples. A needle-plane test arrangement was set up using hypodermic needles. Partial discharge (PD) data was captured using both the IEC 60270 electrical method and radio frequency (RF) sensors, and visual observations are made using a digital microscope. Features of the PD plot that corresponded to electrical tree growth were assessed, evaluating the similarities and differences of both PD measurement techniques. Three univariate phase distributions were extracted from the partial discharge phase-resolved (PRPD) plot and the first four statistical moments were determined. The implications for automated lifetime prediction of insulation samples due to electrical tree development are discussed

Clarification of the optimum silica nanofiller amount for electrical treeing resistance

This paper aims to clarify the optimum amount of fumed silica (SiO2) nanofiller in resisting the initiation and propagation of electrical treeing in silicone rubber (SiR). Unlike other works, SiR/SiO2 nanocomposites containing seven different weight percentages of SiO2 nanofiller were prepared for this purpose. To achieve the objective, the electrical tree characteristics of the SiR/SiO2 nanocomposites were investigated by comparing the tree initiation voltage, tree breakdown time, tree propagation length and tree growth rate with its equivalent unfilled SiR. Moreover, the structural and morphological analyses were conducted on the SiR/SiO2 nanocomposite samples. The results showed that the SiR, when added with an appropriate amount of SiO2 nanofiller, could result in an improved electrical tree resistance. It implies that the 5 wt% of silica is the optimum amount to achieve the optimal electrical tree resistance such that above 5 wt%, the tree resistance performance has been abruptly reduced, subjected to the agglomeration issue

Electrical treeing and partial discharge characteristics of silicone rubber filled with nitride and oxide based nanofillers

This article presents a study on electrical treeing performances with its associated partial discharge (PD) and the influence of filler concentration in silicone rubber (SiR) samples which are filled with silicon dioxide (SiO2) and silicon nitride (Si3N4) as nanofillers for electrical tree growth suppression. There are many researches on electrical treeing in SiR with SiO2 nanofillers but none of the publication have reported on Si3N4 nanofillers for suppression of the electrical tree growth. In this study, the treeing experiments were conducted by applying a fixed AC voltage of 10 kV and 12 kV at power frequency of 50 Hz on unfilled SiR, SiR/SiO2, and SiR/Si3N4 nanocomposites with different filler concentrations by 1, 3, and 5 weight percentage (wt%) and the electrical treeing parameters were observed with its correlated PD patterns. The outcome from this study found that the SiR/Si3N4 nanocomposites were able to withstand the electrical treeing better than the pure SiR or SiR/SiO2 nanocomposites. Furthermore, the increase in filler concentration improved the electrical tree performances of the nanocomposites. This finding suggests the Si3N4 can be used as filler in polymeric insulating materials for electrical tree inhibition. Meanwhile, the PD activity shows increment when the tree progresses thereby indicating correlation in both parameters which can be as key parameter for monitoring unseen electrical treeing in the opaque samples

Electrical treeing performance of silicone rubber filled with plasma-treated nanoparticles

Nanocomposites have gained wide interests as insulating materials due to their excellent ability to resist electrical discharges such as corona discharges, partial discharges, electrical treeing and water treeing. However, surface incompatibility between polymer and nanoparticles is one of the main issues that may reduce their performances towards discharge resistances. Processing techniques of these nanoparticles such as coupling agent and intercalation methods showed excellent performance, but those techniques involved chemical processes. Recently, plasma treatment was introduced as an improved technique to enhance the dispersion of nanocomposites in electrical applications. However, electrical treeing studies on the electrical performance of plasma-treated nanocomposites are lacking. This study presents an investigation on the electrical tree growth performance as well as the effect of nanoparticles concentration of silicone rubber (SiR) filled with silicon dioxide (SiO2) nanoparticles treated with Atmospheric Pressure Plasma (APP). The treatment of the SiO2 nanoparticles’ surfaces with APP is to enhance SiO2 compatibility with SiR matrix. Besides, untreated and silane-treated nanocomposites were also studied for comparison purpose. Constant AC voltage was applied to these untreated, silane and plasma-treated nanocomposites with different nanoparticles concentration of 1, 3 and 5 wt% to investigate their electrical performances i.e. tree initiation time, tree propagation time, growth rate and tree breakdown time. Morphological analysis as well as chemical characterization of the nanoparticles were analyzed using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-ray spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) while, the dispersion of the nanoparticles-polymer matrix were analyzed using FESEM. Results show that plasma-treated SiO2 nanoparticles dispersed uniformly in the SiR polymer matrix. The plasma-treated nanocomposites were able to resist electrical treeing better than untreated and silane-treated nanocomposites. The increase in nanoparticles concentration in all three different treatments has enhanced the electrical tree performance of the nanocomposites. Overall, the result from this study reveals that the plasma-treated nanocomposites showed better efficacy in inhibiting electrical tree growth by as much as 64% as compared to silane-treated nanocomposites that showed an efficacy in electrical tree growth rate reduction by as much as 29%. This indicates that plasma treatment could be an alternative technique to improve surface incompatibility of nanocomposites, and hence, resisting electrical treeing growth

Effect of Humidity on Partial Discharge Characteristics of Epoxy/Boron Nitride Nanocomposite under High Voltage Stress

Partial discharge (PD) may lead to the degradation of insulating materials and affect the lifetime of high voltage equipment. This paper describes the effect of relative humidity on PD characteristic of epoxy/boron nitride (BN) nanocomposite under high voltage (HV) stress. In this work, CIGRE Method II was utilized as an electrode configuration. BN nanofiller was chosen because of its high insulating properties with high thermal conductivity. The PD characteristics such as PD charge magnitude, PD number or occurrence, and average of PD charge during certain of ageing time under HV stress against relative humidity were examined. The results revealed that PD number of humid samples is higher about 8~14% compared to the normal ones. It is considered due to the decrease of surface resistance of the humid samples. The PD charge magnitudes of humid samples are slightly higher compared to the normal ones. The epoxy/BN nanocomposite has lesser PD number and magnitude compared to the neat epoxy samples

Partial Discharge and Breakdown Strength of Plasma Treated Nanosilica/LDPE Nanocomposites

Nanocomposites have been actively studied in recent years as an insulating material due to their excellent in electrical, mechanical and thermal properties. Even though, the addition of nanoparticles into polymer matrices showed better performance in relation to partial discharge (PD) and AC breakdown strength tests. However, the introduction of nanoparticles could lead to the formation of agglomeration of the fillers which may nullify the true capabilities of the composites. Therefore, silane coupling agent was introduced for surface functionalization treatment of the nano filler but among the issues associated are toxicity and complexity. In the present study, atmospheric pressure plasma is proposed to enhance the surface functionalization of the nano filler. This proposed method was used to treat the nanosilica (SiO 2 ) surfaces to enhance the interfacial interaction between the host (LDPE) and nano filler. SiO 2 nano filler was added into the LDPE at weight percentages of 1, 3 and 5%. The phase-resolved PD behaviour and Weibull analysis of AC breakdown strength of untreated and plasma-treated LDPE nanocomposites were measured to evaluate the performance of the samples. As results, the plasma treated LDPE nanocomposites experience apparent increments of the PD resistance and AC breakdown strength as compared to the untreated nanocomposites. It is implied that the plasma treatment of nanosilica has contributed to the enhancement of the filler dispersion and eventually reducing the agglomeration