In this paper,work was conducted to reveal electrical tree behaviors（initiation and propagation）of silicone rubber（SIR） under an impulse voltage with high temperature.Impulse frequencies ranging from 10 Hz to 1 k ...In this paper,work was conducted to reveal electrical tree behaviors（initiation and propagation）of silicone rubber（SIR） under an impulse voltage with high temperature.Impulse frequencies ranging from 10 Hz to 1 k Hz were applied and the temperature was controlled between 30 °C and 90 °C.Experimental results show that tree initiation voltage decreases with increasing pulse frequency,and the descending amplitude is different in different frequency bands.As the pulse frequency increases,more frequent partial discharges occur in the channel,increasing the tree growth rate and the final shape intensity.As for temperature,the initiation voltage decreases and the tree shape becomes denser as the temperature gets higher.Based on differential scanning calorimetry results,we believe that partial segment relaxation of SIR at high temperature leads to a decrease in the initiation voltage.However,the tree growth rate decreases with increasing temperature.Carbonization deposition in the channel under high temperature was observed under microscope and proven by Raman analysis.Different tree growth models considering tree channel characteristics are proposed.It is believed that increasing the conductivity in the tree channel restrains the partial discharge,holding back the tree growth at high temperature.展开更多
Electrical pollution is a worldwide concern,because it is potentially harmful to human health.Trees not only play a significant role in moderating the climate,but also can be used as shields against electrical polluti...Electrical pollution is a worldwide concern,because it is potentially harmful to human health.Trees not only play a significant role in moderating the climate,but also can be used as shields against electrical pollution.Shielding effects on the electric field strength under transmission lines by two tree species,Populus alba and Larix gmelinii,were examined in this study.The electrical resistivity at different heights of trees was measured using a PiCUS sonic tomograph,which can image the electrical impedance for trees.The electric field strength around the trees was measured with an elf field strength measurement system,HI-3604,and combined with tree resistivity to develop a model for calculating the electric field intensity around trees using the finite element method.In addition,the feasibility of the finite element method was confirmed by comparing the calculated results and experimental data.The results showed that the trees did reduce the electric field strength.The electric field intensity was reduced by 95.6%,and P.alba was better than L.gmelinii at shielding.展开更多
A series of solid-solid interfaces, consisting of ceramic-epoxy resin interface samples with a tip-plate electrode, were investigated by performing partial discharge tests and realtime electrical tree observations. A ...A series of solid-solid interfaces, consisting of ceramic-epoxy resin interface samples with a tip-plate electrode, were investigated by performing partial discharge tests and realtime electrical tree observations. A toughening agent was added to the epoxy resin at different ratios for comparison. The impact strength, differential scanning calorimetry （DSC） and dielectric properties of the cured compositions and ceramic were tested. The electric field strength at the tip was calculated based on Maxwell＇s theory. The test results show that the addition of a toughener can improve the impact strength of epoxy resin but it decreases the partial discharge inception voltage （PDIV） of the interface sample. At the same time, toughening leads to complex branches of the electrical tree. The simulation result suggests that this reduction of the PDIV cannot be explained by a change of permittivity due to the addition of a toughening agent. The microstructural change caused by toughening was considered to be the key factor for lower PDIV and complex electrical tree branches.展开更多
基金supported in part by National Basic Research Program of China(973 Project)(No.2014CB239501)National Natural Science Foundation of China(Nos.51707100,51377089)+1 种基金State Key Laboratory of Electrical Insulation and Power Equipment(No.EIPE16208)China Postdoctoral Science Foundation(No.2016M591176)
文摘In this paper,work was conducted to reveal electrical tree behaviors（initiation and propagation）of silicone rubber（SIR） under an impulse voltage with high temperature.Impulse frequencies ranging from 10 Hz to 1 k Hz were applied and the temperature was controlled between 30 °C and 90 °C.Experimental results show that tree initiation voltage decreases with increasing pulse frequency,and the descending amplitude is different in different frequency bands.As the pulse frequency increases,more frequent partial discharges occur in the channel,increasing the tree growth rate and the final shape intensity.As for temperature,the initiation voltage decreases and the tree shape becomes denser as the temperature gets higher.Based on differential scanning calorimetry results,we believe that partial segment relaxation of SIR at high temperature leads to a decrease in the initiation voltage.However,the tree growth rate decreases with increasing temperature.Carbonization deposition in the channel under high temperature was observed under microscope and proven by Raman analysis.Different tree growth models considering tree channel characteristics are proposed.It is believed that increasing the conductivity in the tree channel restrains the partial discharge,holding back the tree growth at high temperature.
基金financially supported by the National Key Research and Development Program(2017YFD0600101)the Central University Basic Research and Operating Expenses of Special Funding(2572016CB04)the Harbin Application Technology Research and Development Projects(2016RQQXJ134)
文摘Electrical pollution is a worldwide concern,because it is potentially harmful to human health.Trees not only play a significant role in moderating the climate,but also can be used as shields against electrical pollution.Shielding effects on the electric field strength under transmission lines by two tree species,Populus alba and Larix gmelinii,were examined in this study.The electrical resistivity at different heights of trees was measured using a PiCUS sonic tomograph,which can image the electrical impedance for trees.The electric field strength around the trees was measured with an elf field strength measurement system,HI-3604,and combined with tree resistivity to develop a model for calculating the electric field intensity around trees using the finite element method.In addition,the feasibility of the finite element method was confirmed by comparing the calculated results and experimental data.The results showed that the trees did reduce the electric field strength.The electric field intensity was reduced by 95.6%,and P.alba was better than L.gmelinii at shielding.
基金Supported by China Academy of Engineering Physics(Project 2014B05005)
文摘A series of solid-solid interfaces, consisting of ceramic-epoxy resin interface samples with a tip-plate electrode, were investigated by performing partial discharge tests and realtime electrical tree observations. A toughening agent was added to the epoxy resin at different ratios for comparison. The impact strength, differential scanning calorimetry （DSC） and dielectric properties of the cured compositions and ceramic were tested. The electric field strength at the tip was calculated based on Maxwell＇s theory. The test results show that the addition of a toughener can improve the impact strength of epoxy resin but it decreases the partial discharge inception voltage （PDIV） of the interface sample. At the same time, toughening leads to complex branches of the electrical tree. The simulation result suggests that this reduction of the PDIV cannot be explained by a change of permittivity due to the addition of a toughening agent. The microstructural change caused by toughening was considered to be the key factor for lower PDIV and complex electrical tree branches.
