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Ethylene propylene diene monomer (EPDM) is broadly employed as an insulating material for high voltage applications. Surface discharge‐induced thermal depolymerization and carbon tracking adversely affect its performance. This work reports the electrical field modeling, carbon tracking lifetime, infrared thermal distribution, and leakage current development on EPDMbased insulation with the addition of nano‐BN (boron nitride) contents. Melt mixing and compression molding techniques were used for the fabrication of nanocomposites. An electricaltracking resistance test was carried out as per IEC‐60587. Simulation results show that contamination significantly distorted the electrical field distribution and induced dry band arcing. Experimental results indicate that electric field stress was noticed significantly higher at theintersection of insulation and edges of the area of contamination. Moreover, the field substantially intensified with the increasing voltage levels. Experimental results show improved carbonized tracking lifetime with the addition of nano‐BN contents. Furthermore, surface temperature was reduced in the critical contamination flow path. The third harmonic component in the leakage current declined with the increase of the nano‐BN contents. It is concluded that addition of nano‐BN imparts a better tracking failure time, and this is attributed to better thermal conductivity and thermal stability, as well as an improved shielding effect to electrical discharges on the surface of nanocomposite insulators.

Surface flashover of spacers is a key factor limiting the application of HVDC GIS/GIL, while the charge accumulation on the surface of the spacer could have a potential adverse effect on the surface flashover voltage. This paper discusses the laws regarding distribution patterns of surface charges and the related mechanism. The field-dependent property is discussed in detail to comprehensively illustrate the charge transport mechanism and explain the research differences regarding different surface charge patterns obtained by previous researchers. In addition, the main surface charge control methods for epoxy resin are summarized and discussed. The potential research directions of charge control methods and key points in manufacturing of spacers used in HVDC GIS/GIL are also prospected.

For outdoor electrical insulation applications, ethylene propylene diene monomer (EPDM) is among the most prominent materials by virtue of its better contamination performance in the field. However, EPDM is prone to thermally depolymerize due to temperature build-up on the surface during dry band arcing which initiates carbonized tracking. This paper investigates the tracking lifetime and thermal distribution of functionalized nano-BN filled EPDM matrix. BN particles (50 nm) were procured for the fabrication of EPDM nanocomposites. The inclined plane test according to IEC 60587 was carried out; the tracking voltage method 2 was adopted with an initial applied voltage of 3 kV and a ramping rate of 0.25 kV/h until failure. Measurement results show nanocomposites exhibit substantially higher tracking failure time as compared to pristine form of EPDM and linearly increased with BN addition. Moreover, maximum surface temperature is remarkably reduced in the nanocomposites which could be due to better thermal stability and thermal conductivity. Furthermore, the nano-BN increase the surface area of particles in the nanocomposites due to smaller interparticle distances which provides better barrier to dry band arcing.

Thermal depolymerisation induced tracking and erosion of polymeric insulators is one of the key insulation failure modes and this process adversely affects the reliability of power delivery networks. This study reports the tracking, erosion and thermal distribution of micron-AlN and micron-AlN + nano-SiO 2 co-filled silicone rubber composites. A tracking-erosion model is presented to explain how the co-filled set of particles directly affects such mechanisms. Aluminium nitride (AlN: 5–10 μm) and silica (SiO 2: 20 nm) particles were procured for fabricating test samples. The inclined plane test according to IEC 60587 was carried out using tracking voltage method 2 with an initial applied voltage of 3 kV and a ramping rate of 0.25 kV/h over the duration of 240 min. Measurement results show co-filled composites exhibit significantly lower physical tracking and erosion as compared to micron-AlN filled composites. Thermal accumulation and average leakage current in co-filled composites are found noticeably lower than micron-filled counterparts. Moreover, the increased surface area of the combined co-filled particles in the composites provides better scattering and reduce secondary electron collision. This may impede the release of high energy causing thermal degradation.

Silicone rubber is a hydrophobic polymer which is widely employed for high voltage outdoor insulation. The material offers excellent electrical performance under contaminated environments. However, pristine silicone rubber has low thermal properties and this may cause tracking and erosion failure due to severe dry band arcing and ohmic heating on the insulating surface. This work investigates the effect of material thermal characteristics on the tracking and erosion resistance of silicone rubber filled with micron sized alumina tri-hydrate (ATH), aluminum nitride (AlN) and boron nitride (BN) particles. Composites with different loading were synthesized by dispersing particles in pristine room temperature vulcanizing (RTV) silicone rubber and IEC 60587 inclined plane test (IPT) was conducted to evaluate tracking and erosion resistance. Apart from physical parameters and leakage current, an infrared thermal imager was used to measure the surface temperature distribution during the course of IPT. Experimental results showed tracking and erosion resistance is significantly enhanced with addition of BN particles followed by ATH. AlN composites exhibit poor tracking and erosion resistance, similar to pristine silicone rubber. It is concluded that addition of BN-composites improves ability to impede the tracking and erosion process, the reasons being better thermal stability and enhanced thermal conduction in the discharge region. On the other hand, infrared analysis revealed thermal accumulation is remarkably higher in AlN-composites which promotes dry band arcing and results in tracking and erosion failure.

Ethylene propylene diene monomer (EPDM) is a polymeric material widely used for high-voltage insulation. This work reports the dielectricand thermal properties of EPDM co-filled with micro- and nano-BN particles. EPDM composite samples with different micro and micro/nanoco-filled contents are prepared by melt-blending and followed by hot press application. Measurements were made including broadbanddielectric spectroscopy, thermogravimetric analysis and thermal conductivity. Experimental findings indicate that Micro-25 wt% + Nano-5 wt% performs better in terms of dielectric loss and conductivity whilst the dielectric constant is measured lower in Micro-29 wt% +Nano-1 wt% relative to the equivalent micron filled Micro-30 wt%. Moreover, the initial degradation temperature and final residual massesof co-filled composites are found considerably higher. The thermal conductivity of EPDM is highly influenced by the introduction ofco-filled set of particles and it is measured about 0.465 W/m.K in Micro-29 wt% + Nano-1 wt% which is 18% higher than Micro-30 wt%.It is likely that the denser packing geometry due to co-filled set of particles inside the EPDM matrix improves the dielectric and thermalproperties which make such composites more attractive for electrical insulation applications.

This study attempts to elucidate whether the addition of micro and/or nano silica (SiO2) particles can enhance the resistance of pure polydimethylsiloxane (PDMS) against synergistic effects of UV, temperature and high voltage stress. Four types of composites (U-SR, M-SR, MN-SR and N-SR) are fabricated by adding micro and/or nano silica particles and then subjected to multi-stress degradation in a test chamber. Results show that there is an apparent surface discoloration in the form of yellowish pale tint and a significant resistance to hydrophobicity reduction is offered by N-SR and MN-SR followed by M-SR and U-SR. SEM and surface roughness findings proclaimed that N-SR and MN-SR offer excellent resistance against filler exposure and increase in surface roughness. There is a minor reduction in absorbance level of Si (CH3)2 and Si-O-Si functional groups of composites but interestingly, hydrophilic hydroxyl group absorbance level is found higher in the U-SR comparatively. Furthermore, dielectric response measurements indicate considerable sensitivity to weathering with N-SR and MN-SR giving the lowest dielectric loss. Results indicate that the addition of nano silica to pure and micro silica filled SR can enhance its UV weathering resistance considerably by building an effective UV shielding layer.

Polymeric materials such as silicone rubber (SiR) are widely used in high voltage outdoor insulating systems and it has been shown that a practical solution to improve the thermal characteristics of SiR is to add micro-sized inorganic particles. Regarding its electrical performance in long-term operation under wet and polluted environment, one of the main selection criteria is its resistance against surface tracking and erosion. In this paper, the tracking and erosion resistance of SiR filled with micron alumina trihydrate (ATH) and aluminium nitride (AlN) is compared along with thermal conductivity and thermal dissipation performance. For the experiment, test samples are prepared by dispersing micro-sized ATH and AlN fillers into room temperature vulcanizing SiR at different loadings. The dispersion process includes the traditional mechanical mixing followed by ultra-sonication. For each test sample, the inclined plane test according to IEC 60587 Standard was carried out, lasted for 4 hours with initial applied voltage of 3 kV and then increased at a rate of 0.25 kV/h. Experimental results show that with the increase in content of both AlN and ATH micro-fillers (from 0 to 30 wt%), the thermal conductivity of SiR composite increases. The lesser erosion depth and leakage current are noticed in the ATH filled composites. Thermal distribution findings indicate that heat is mainly accumulated in the discharge area and ATH dissipates it more efficiently than AlN which results in better tracking and erosion resistance.

Due to the complex design and high costs of production, solar thermal systems have fallen behind in the world of alternative energy systems. Different mechanisms are applied to increase the efficiency of the solar collectors and to reduce the cost. Solar tracking system is the most appropriate technology to increase the efficiency of solar collectors as well as solar power plants by tracking the sun timely. In order to maximize the efficiency of collectors, one needs to keep the reflecting surface of parabolic trough collectors perpendicular to the sun rays. For thispurpose microcontroller based real time sun tracker is designed which is controlled by an intelligent algorithm using shadow technique. The aim of the research project is to test the solar-to-thermal energy efficiency by tracking parabolic trough collector (PTC). The energy efficiency is determined by measuring the temperature rise of working fluid as it flows through the receiver of the collector when it is properly focused. The design tracker is also simulated to check its accuracy. The main purpose to design this embedded system is to increase the efficiency and reliability of solar plants by reducing size, complexity and cost of product.