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Polymers are widely used as insulation materials in the electrical industry because their existing electrical and mechanical properties can be altered by adding different types of additives. Successful prediction of the service life of the insulators used in the electrical industry is important for the reliability of the system. For this purpose, insulating materials are subjected to tests according to various standards. In this study, unlike the literature, a polymeric insulator was produced by adding 3 wt.% zinc oxide (ZnO), magnetite (Fe3O4), and nickel (Ni) into the polyester. The produced samples were subjected to the inclined plane test in accordance with ASTM (American Society for Testing and Materials) D-2303 standards. In order to analyze the electric and magnetic field distributions formed on the samples during the inclined plane test, first, the current flowing on the samples during the test was measured. Following this, analyses were carried out by creating a simulation model of the samples. Studies found in the literature mainly focus on two-dimensional investigation of the electrical field distribution. This study concentrates on the three-dimensional examination of the electrical field also considering the magnetic field distribution. Results of this study showed that prior numerical analysis gives insight into information about the real-life behavior of the samples. [ABSTRACT FROM AUTHOR]

Our previous study revealed that early application of electrical field stimulation (EFS) with the anode at the lesion and the cathode distal to the lesion reduced injury potential, inhibited secondary injury and was neuroprotective in the dorsal corticospinal tract after spinal cord injury (SCI). The objective of this study was to further evaluate the effect of EFS on protection of anterior horn motoneurons and their target musculature after SCI and its mechanism. Rats were randomized into three equal groups. The EFS group received EFS for 30 minutes immediately after injury at T10. SCI group rats were only subjected to SCI and sham group rats were only subjected to laminectomy. Luxol fast blue staining demonstrated that spinal cord tissue in the injury center was better protected; cross-sectional area and perimeter of injured tissue were significantly smaller in the EFS group than in the SCI group. Immunofluorescence and transmission electron microscopy showed that the number of spinal cord anterior horn motoneurons was greater and the number of abnormal neurons reduced in the EFS group compared with the SCI group. Wet weight and cross-sectional area of vastus lateralis muscles were smaller in the SCI group to in the sham group. However, EFS improved muscle atrophy and behavioral examination showed that EFS significantly increased the angle in the inclined plane test and Tarlov’s motor grading score. The above results confirm that early EFS can effectively impede spinal cord anterior horn motoneuron loss, promote motor function recovery and reduce muscle atrophy in rats after SCI.

In this paper a study on effects of AC and DC dry band arcing on silicone rubber insulators surface is presented. The insulators tested are commercially available, having as their main material silicone rubber with alumina trihydrate as an additive. In addition to literature analysis, experiments were performed following the inclined plane test method described in the ASTM D2303. It was found that the voltage type (AC or DC) and polarity (positive or negative) influence not only the damage caused by the dry band arcing, but also the average value and the behavior of the leakage current. The voltage type that caused the most damage on the insulating material was DC with positive polarity, followed by DC with negative polarity, then AC. According to other studies, the difference in the results obtained with different voltage types are mainly caused by the ion release on the electrodes, behavior of the contaminant under the electric field and the length and duration of the dry band arcs. This shows that silicone rubber insulators should not be utilized in DC systems with same voltage as the ones that are designed to withstand AC, unless modifications are made in the material properties or in the insulators design. [ABSTRACT FROM AUTHOR]

This paper investigates partial discharge (PD) characteristics that lead to the erosion of silicone rubber (SR) polymer under AC stress and DC stress of both polarities. The experiments are performed on high temperature vulcanized (HTV) SR material samples. The inclined plane test apparatus, constructed in accordance with IEC 60587 requirements, is employed to produce the surface partial discharges and the resulting accelerated aging of the specimens. Two commercial instruments are used to obtain the PD data. A concurrent analysis of visual observations of discharge and PD data is performed to classify discharges based on the severity of material degradation that each type causes. Three types of PD are identified and characterized using diagrams of charge magnitude versus time and a signal processing technique called time-frequency mapping. Individual pulse waveshapes of each type of discharge are also analyzed. PD pulse waveforms are analyzed according to their amplitude, energy, pulse width, and frequency spectrum. These pulse waveform parameters are evaluated and compared for the eroding discharge pulses under AC and DC voltage stresses. It is found that the stages of material degradation during IPT are related to the variations in discharge magnitude and the location of pulse clusters on the time-frequency maps.

Cross-linked polyethylene (XLPE) and silicone rubber (SiR) samples were subjected to a high-voltage AC stress plane–plane configuration and inclined plane test, respectively. The voltage was applied such that discharge was observed across the surface of the XLPE test sample for several hours and for visible damage to occur on SiR samples also after several hours. Selected stressed samples together with virgin samples from the same manufactured batch were tested using nuclear magnetic resonance (NMR) spectroscopy. Specifically, ^1H NMR spin–lattice (T(1)) and spin–spin (T(2)) relaxation time measurements were employed to examine potential changes in the chemical bonding of undamaged and damaged XLPE and SiR samples. Preliminary results show that there may be a moderate increase in the T(1) and T(2) values of the damaged samples in comparison with the undamaged ones. This raises the possibility that NMR can be a useful additional experimental tool in characterising material 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. [ABSTRACT FROM AUTHOR]

In recent years, silicone rubber-based composites have been widely investigated for outdoor applications due to their promising insulating properties. However, mechanical, thermal, and tracking properties of pure silicone rubber are very poor, which restrains its application for long-term performance. In this research work, the influence of microsized alumina trihydrate (ATH) and micro/nanosized silica (SiO2) fillers on mechanical, thermal, and electrical properties of room temperature vulcanized silicone rubber (RTV-SiR) has been studied. SiR-blends with varying amounts of ATH and SiO2 particles were prepared by blending in a two-roll mixing mill, compression molding, and postcuring processes in sequence. In order to evaluate relative tracking and erosion resistance of SiR-blends, an inclined plane test (IPT) was conducted in accordance with the ASTM D2303 standard procedure. Surface temperature distribution was recorded using a Fluke-Ti25 infrared camera during IPT experiments. Thermogravimetric analysis was carried out to analyze the thermal stability of ATH and silica-filled silicone rubber samples. Tensile strength, percent elongation at break, hardness, erosion, tracking resistance, and thermal properties were also investigated and discussed. Results showed that the mechanical, thermal, tracking, and erosion performances of SiR-blends are improved by the incorporation of ATH and silica particles, which is governed by filler type, size, and wt.% in the polymer matrix. [ABSTRACT FROM AUTHOR]

Abstract How to effectively enhance the tracking and erosion resistance of silicone rubber is a significant topic in high-voltage insulation. In this work, ureido-modified MQ silicone resin (UHMQ) was synthesized and employed to improve tracking and erosion resistance of silicone rubber in combination with platinum (Pt). The effect and mechanism of UHMQ/Pt on tracking and erosion resistance were studied via inclined plane test, leakage current curves, scanning electron microscopy, thermogravimetry and thermogravimetry-Fourier transform infrared spectrometry. When 5–7 phr of UHMQ and 0.33 phr of Pt catalyst were added, the tracking and erosion resistance of silicone rubber were greatly improved. In this case, all specimens passed the inclined plane test at 4.5 kV with low eroded mass and undamaged surfaces. The thermal stability of silicone rubber containing UHMQ/Pt was also much higher than that without, and the leakage current and discharging frequency on the surface of silicone rubber were markedly decreased with the introduction of UHMQ/Pt. This was attributed to UHMQ/Pt catalyzing radical crosslinking of silicone chains under arc discharging so that a protective barrier was established on the surface to resist arc ablation. Also, the enhanced radical mechanism suppressed degradation of silicone chains, and thus reduced release of cyclic oligomers which would aggravate arc discharging. Furthermore, since UHMQ/Pt facilitated complete oxidation of pyrolysis gases, the carbon deposit was reduced and tracking was suppressed. Highlights • Ureido-modified MQ silicone resin (UHMQ) and platinum (Pt) were introduced into silicone rubber. • UHMQ/Pt could significantly improve the thermal stability and tracking and erosion resistance of silicone rubber. • UHMQ/Pt reduced average leakage current and discharging frequency on the surface of silicone rubber. • The TG-FTIR of evolved gases during heating was performed. • The possible suppression mechanism of UHMQ/Pt on tracking and erosion of silicone rubber was proposed. [ABSTRACT FROM AUTHOR]

We developed a forced non-electric-shock running wheel (FNESRW) system that provides rats with high-intensity exercise training using automatic exercise training patterns that are controlled by a microcontroller. The proposed system successfully makes a breakthrough in the traditional motorized running wheel to allow rats to perform high-intensity training and to enable comparisons with the treadmill at the same exercise intensity without any electric shock. A polyvinyl chloride runway with a rough rubber surface was coated on the periphery of the wheel so as to permit automatic acceleration training, and which allowed the rats to run consistently at high speeds (30 m/min for 1 h). An animal ischemic stroke model was used to validate the proposed system. FNESRW, treadmill, control, and sham groups were studied. The FNESRW and treadmill groups underwent 3 weeks of endurance running training. After 3 weeks, the experiments of middle cerebral artery occlusion, the modified neurological severity score (mNSS), an inclined plane test, and triphenyltetrazolium chloride were performed to evaluate the effectiveness of the proposed platform. The proposed platform showed that enhancement of motor function, mNSS, and infarct volumes was significantly stronger in the FNESRW group than the control group (P

The synthesis of symmetric dimeric camphor derivatives containing two quaternary nitrogen atoms was performed and their myorelaxant activity in mice was evaluated. For the comparison, some salts derived from meta- and para-xylylene dibromides were synthesized and their activity was tested. [ABSTRACT FROM AUTHOR]

This paper describes an investigation into the dry-band arcing mechanism leading to erosion of filled silicone rubber in the DC inclined plane test. Good correlation is obtained between the formation of surface residue, hotspots and the eroding dry-band arcing. The hotspots detected by infrared camera correlates well with the temperature of degradation determined by thermogravimetric analysis and differential scanning calorimetry. To characterize the physical mechanism of dry-band arcing, wavelet-based multiresolution analysis up to seven levels of resolution is applied to the leakage current waveforms. The analysis shows that both stable and intense discharges characterize the eroding dry-band arcing. A time-to-eroding parameter is proposed to determine the relative resistance to the formation of residue. Faster accumulation of residue is evident under -DC than +DC. Earlier inception of erosion is obtained for the silica filled- as compared to the alumina tri-hydrate filled- silicone, in which the release of the water of hydration is postulated to suppress the residue formation. [ABSTRACT FROM AUTHOR]

In this paper, the performance of silicone rubber composites containing 0, 10 and 30 wt % loading of silica filler is investigated in the initial-tracking voltage test method of the inclined plane test under AC and DC showing the most inferior erosion class under +DC followed by ?DC and then AC. DC as compared to AC dry-band arcing characteristics are analyzed by conducting leakage current measurements prior to and after the inception of dry-band arcing. At high test voltages, instability of the contaminant rivulet is found to be an important factor in the development of dry band arcing and, consequently, biasing the test outcomes when equal voltages of rms AC and DC are selected. The initial tracking voltage in ASTM D2303 is, therefore, proposed as a reliable approach by which +DC and ?DC test voltages can be reliably selected. A coefficient of variation parameter is also proposed as a useful mean of selecting the equivalent DC voltages, and the validity of the parameter is verified experimentally using the initialtracking voltage test method. Erosion in the constant voltage method is investigated under DC by applying the equivalent voltages and compared to AC. Based on this methodology, it is suggested that an improvement in silicone rubber compositions is needed for DC. Moreover, the need to select the creepage distance of polymer insulators designed for AC, yet to be used under DC, with reference to tracking/erosion performance is highlighted. [ABSTRACT FROM AUTHOR]

Romania has a large number of waste dumps and unconfirmed landfills and their closing should be a priority. An adequate design of a closing system should consider parameters such as friction resistance on the various involved interfaces, between geosynthetic materials and soils. These parameters can be determined experimentally by direct shear tests or using the inclined plane test. In the Geotechnical and Foundation laboratory of UTCB an inclined plane apparatus (a device which, despite its simplicity, does not exist in Romania) has been developed. The inclined plane test is used to determine the interface characteristics of two geosynthetic materials or a geosynthetic material in contact with a soil. This test is used mainly in situations where vertical stresses are low, such as cover systems for landfills or for erosion control of slopes. The paper presents the principle of this method and how to determine the angle of friction at the interface in accordance to SR EN ISO 12957-2 "Determination of friction characteristics. Part 2: Inclined plane test". It also presents the calibration of an inclined plane device made in the Geotechnical and Foundation laboratory, together with the experimental program and the results obtained with this device, as well as a comparison with the results of a previous direct shear experimental program. [ABSTRACT FROM AUTHOR]

Abstract: On wet days, environmental contamination of outdoor insulation surfaces can reduce the reliability of electrical transmission systems and lead to flashover and arcing over the entire insulator. The use of superhydrophobic coatings would resolve this problem due to their self-cleaning effect. Water droplets can pick up dirt particles and remove contamination from the surfaces of insulators. This paper reports on a study to make a superhydrophobic RTV silicone rubber coating that has contact angles of higher than 145° and good UV durability. The Inclined Plane Test, water durability test and adhesion test are presented to show the effectiveness of this coating and the best formulations. The results of tracking and erosion resistance test (Inclined Plane Test) showed that formulations with at least 35wt% ATH can be used for superhydrophobic RTV insulator coatings. [Copyright &y& Elsevier]

Abstract: The inclined plane test (IPT) is commonly performed to measure the interface shear strength between different materials as those used in cover systems of landfills. The test, when interpreted according to European test Standards provides the static interface friction angle, usually assumed for 50mm displacement and denoted as . However, if interpreted considering the several phases of the sliding process, the test is capable of yielding more realistic information about the interface shear strength such as differentiating interfaces which exhibit the same value of but different behavior for displacement less than 50mm. In this paper, the IPT is used to evaluate the interface shear strength of some materials usually present in cover liner systems of landfill. The results of the tests were analyzed for both, the static and the dynamic phases of the sliding and were interpreted based on the static initial friction angle, ϕ 0, and the limit friction angle, ϕ lim. It is shown that depending on the sliding behavior of the interfaces, , which is usually adopted as the designing parameter in stability analysis, can be larger than ϕ 0 and ϕ lim. [Copyright &y& Elsevier]

A salt fog test and an inclined plane test have been combined in order to trace changes in electrical and mechanical properties as well as in chemical stability of high temperature cured silicone rubber (HTV) samples containing interfaces. The interfaces were created in two different ways. The first technique, named adding/curing, was based on pressing together an uncured HTV silicone plate towards a piece of already cured one, followed by curing at atmospheric pressure and high temperature. The second type of interface was made by joining two pieces of cured HTV rubber by silicone glue (RTV-I). Thereafter both types of samples were divided in two parts, one of which was additionally exposed to UV-radiation before testing. The combined salt fog — inclined plane test did not reveal significant differences in the development of leakage currents, in the change of surface roughness, or in the degree of surface oxidation in comparison to reference samples of cured HTV rubber without interfaces. At the same time the leakage currents became lower on the UV-exposed samples. It is suggested that the reduction in leakage currents resulted from a combination of increased surface roughness and increased hydrophobicity. Reduction of mechanical properties of UV-exposed samples was also observed. The tensile testing showed that samples containing the adding/curing interfaces maintained their mechanical strength after ageing while the strength of the glued samples was significantly reduced, indicating that the adding/curing system has better long-term mechanical stability compared to the glued system. [ABSTRACT FROM AUTHOR]

Silicone rubber samples, filled with 30% alumina trihydrate, subjected to the ASTM inclined plane test, show good correlation between the measured harmonic power components of dry band arcing and the surface temperature recorded with a thermovision camera. The simultaneous study of the low frequency Fast Fourier Transform and variations in temperature shows that when the temperature rises above 100°C there is a well defined increase in the low frequency harmonic components of the measured power; however, this trend is not verified by the fundamental component. The eroded mass of the samples is measured independently by a laser approach and a model to rank the tested samples using the Inclined Plane Test is developed. The model is validated by applying it to both the recorded harmonic power components and temperature, resulting in the correct ranking of damage on the samples tested in the Inclined Plane test. [ABSTRACT FROM AUTHOR]

The use of geosynthetic lining systems (GLS) is increasingly widespread in hydraulic civil engineering structures. Studying their stability generally requires calculating their friction angle materials. This is carried out using a shear box or an inclined plane, the latter being more appropriate for the cases of low normal stress. The design and construction of an inclined plane that respects the existing standards is described. The test also enables under hydraulic conditions to study the influence of water on GLS stability. A large number of interfaces were tested in dry and wet conditions, these tests enabled us to verify the influence of water on GLS stability. An in situ experiment was carried out with the aim of validating the inclined plane tests. Finally, on the basis of the experiment result, stability calculations for an example are presented. These highlight the need to take the effect of water into account when designing such systems. [Copyright &y& Elsevier]

This paper investigates partial discharge (PD) characteristics that lead to the erosion of silicone rubber (SR) polymer under AC stress and DC stress of both polarities. The experiments are performed on high temperature vulcanized (HTV) SR material samples. The inclined plane test apparatus, constructed in accordance with IEC 60587 requirements, is employed to produce the surface partial discharges and the resulting accelerated aging of the specimens. Two commercial instruments are used to obtain the PD data. A concurrent analysis of visual observations of discharge and PD data is performed to classify discharges based on the severity of material degradation that each type causes. Three types of PD are identified and characterized using diagrams of charge magnitude versus time and a signal processing technique called time-frequency mapping. Individual pulse waveshapes of each type of discharge are also analyzed. PD pulse waveforms are analyzed according to their amplitude, energy, pulse width, and frequency spectrum. These pulse waveform parameters are evaluated and compared for the eroding discharge pulses under AC and DC voltage stresses. It is found that the stages of material degradation during IPT are related to the variations in discharge magnitude and the location of pulse clusters on the time-frequency maps. [ABSTRACT FROM AUTHOR]

The neurological effects of four synthetic pyrethroids resmethrin, permethrin, cypermethrin, and deltamethrin have been investigated in the rat to establish whether there is a correlation between the clinical-functional status of the animal and peripheral nerve damage as measured biochemically. Neuromuscular dysfunction was assessed by means of the inclined plane test and peripheral nerve damage by reference to β-glucuronidase and β-galactosidase activity increases in nerve tissue homogenates from treated and control animals. A transient functional impairment was found in animals treated with any one of the four pyrethroids tested and in all cases this was maximal at the end of the 7 day subacute dosing regimen. Significant increases in β-glucuronidase and β-galactosidase were found 3-4 weeks after the start of dosing in the distal portion of the sciatic/posterior tibial nerves from permethrin, cypermethrin, and deltamethrin treated animal; but no changes were found in remesthrin-dosed animals. It is concluded therefore, that there is no direct correlation between the time-course of the neuromuscular dysfunction and the neurobiochemical changes. This suggests that these pyrethroids have at least two distinct actions - a short-term pharmacological effect and at near-lethal dose levels a more chronic neurotoxic effect that results in sparse axonal nerve damage. [ABSTRACT FROM AUTHOR]

• Sliding mode observer was proposed to estimate dynamic surface resistance of insulating material. • Estimated resistance was used to reliably indicate the onset of failure. • Performance and efficacy of the observer was verified via experimental and simulation studies. • Observer accurately reconstructs the true resistance profiles even with measurement noise. An important mode of failure of composite insulators using polymeric materials is tracking and erosion. Traditional laboratory tests that monitor leakage current alone are not adequate for predicting failure. Two second order sliding mode observers have been evaluated to determine if they can predict failure better than monitoring leakage current alone. The efficacy of the estimation algorithms was validated via experiments and computer simulations. It has been shown probably for the first time that the observers provide a more reliable indication of failure than provided by the commonly followed practice of monitoring leakage current. [ABSTRACT FROM AUTHOR]