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A dielectric breakdown phenomenon on polymer sur-faces calledtrackingfailure was observed[1].Itis caused bycarbonized conductive tracks formed on their surfaces .Whensufficientlyintensive discharge lasted for a consider-abletime ,the decomposedcarbon prod… 相似文献
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In tracking test,discharge is a complicated process and comparative tracking index(CTI)has wide variation.To evaluate tracking resistance,the chaos analysis of discharge current is presented based on the tracking test ofphenolic resin in accordance with IEC601 12.According to the characteristics of statistical self-similarity and complexity of discharge current,the largest Lyapunov exponent is calculated,and the 2-dimensional attractor ofdischarge current is reconstructed.Moreover,the attractors of discharge current and recurrence plots of different discharge states are reconstructed.The results indicate that the chaos attractors have different characteristics in evolutionary tracks,the topological structure and grain direction of recurrence plots show significant differences.The chaos attractor can describe the tracking process,the recurrence plot can identify the tracking state clearly,while its arithmetic is simple. 相似文献
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Low-density polyethylene ( LDPE) film andhigh-density polyethylene (HDPE) film are two typi-cal polyethylene films and widely used in electricaland electronic equipment, such as covering and corein ultra-high frequency cables[1—3]. It is well knownthat the unexpected defects in insulating polyethylenefilms under a high voltage will lead to the occurrenceof insulation degradation and act as the beginning ofinsulation breakdown. The insulation degradation ad-vances not only with the accumula… 相似文献
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Tracking tests for different polymer materials were carried out to investigate the chaotic behavior of surface discharge.The discharge sequences measured during the discharge process were analyzed for finding the evidence of chaos existence.Four kinds of nonlinear analysis methods were adopted:estimating the largest Lyapunov exponent,calculating the fractal dimension with increasing the embedding dimension,drawing the recurrence plots,and plotting the Poincare maps.It is found that the largest Lyapunov exponent of the discharge is positive,and the plot of fractal dimension,as a function of embedding dimension,will saturate at a value.The recurrence plots show the chaotic frame-work patterns,and the Poincare maps also have the chaotic characteristics.The results indicate that the chaotic behavior does exist in the discharge currents of the tracking test. 相似文献
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A big operational problem of high voltage (HV)power equipments is the degradation of the insulation,to which partial discharge (PD) is a major contribu-tion. Currently, the main collectingtechniques for PDsignals include the electrical pulse associated withPD, the electromagnetic waves detection method andthe acoustic detection method. PD generates acousticwaves, which can be used to detect the intensity andlocation of the PD. Compared with the detectionmethods, the acoustic methods have a… 相似文献
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介绍了广域测量系统的开发应用,PMU布点配置原则,以及采用可观性分析和同调性分析结合的蒙西电网PMU布点方法分析。 相似文献
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Epoxy resin laminate onto which a pair of copper foil was printed was employed as test samples.The samples were placed in an artificial atmospheric chamber, which was vacuumed by a rotary pump from 100 kPa to 5 kPa.The magnetic field was produced by permanent magnets that were assembled to make E×B drift away from, into and parallel to the sample surface, respectively.Magnetic flux density was adjusted at 120 mT, 180 mT and 240 mT respectively.By applying a negative bias voltage between the electrodes, the time to surface breakdown was recorded.Obtained results show that when E×B is into the surface, the time to the breakdown is shortened;when E×B is away from the surface, the time to the breakdown is delayed;when E×B is parallel to the surface, the time to the breakdown remains approximately the same as the case without magnetic field.With the decrease of pressure, the time to the breakdown increases and the effect of magnetic field on breakdown appears to be strengthened. 相似文献
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To develop a measurement system for monitoring partial discharge （PD） without the effect of external interferences,an algorithm of PD signal extraction based on wavelet transform with Teager＇s energy operators was presented. Acoustic signal generated by PD was selected to remove excessive interfering signals and electromagnetic interferences. Acoustic signals were collected and decomposed into I0 levels by wavelet transform into approximation and detail components. “Daubechies 25” was proved to be the most suitable mother wavelet for the extraction of PD acoustic signals. Compared with conventional wavelet denoising method, Teager＇s energy operators were adopted to the PD signal reconstruction and the signal to noise ratio was in creased by 20%-25% inthe experiment,without lost in energy and pulse amplitude. 相似文献
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