In urban power networks,a common practice is to bond numerous high-voltage cable circuits to a single grounding grid located in underground tunnels,primarily for reasons of installation convenience.In these situations...In urban power networks,a common practice is to bond numerous high-voltage cable circuits to a single grounding grid located in underground tunnels,primarily for reasons of installation convenience.In these situations,excessively high levels of sheath currents were often detected during routine inspections,but no electrical faults were found to be responsible.Previous publications ignored the currents flowing through the shared grounding points into the closed sheath loops of different circuits.In this paper,a mathematical model is established for the current circulating among sheath loops of different circuits,and the factors influencing the circulating current were analysed.The abnormal excessive sheath current is demonstrated to be an increase in the circulating current due to the combined effect of electromagnetic coupling and the shared grounding grid.The circulating current depends on the induced voltages which,in turn,depends on the cable layouts and load currents.The effects of these factors are evaluated in various scenarios.The increase of the circulating current is verified in a field case where four electrically healthy cable circuits sharing the same grounding points were found to have abnormal excessive sheath currents.展开更多
Intrinsic Josephson junctions in misaligned T12Ba2CaCu208 thin film were fabricated on LaA103 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the cu...Intrinsic Josephson junctions in misaligned T12Ba2CaCu208 thin film were fabricated on LaA103 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.展开更多
Intrinsic Josephson junctions in misaligned Tl2Ba2CaCu2O8 thin film were fabricated on LaAlO3 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the cu...Intrinsic Josephson junctions in misaligned Tl2Ba2CaCu2O8 thin film were fabricated on LaAlO3 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.展开更多
It has been a scientific and technological problem in the field of microelectronics for several decades that the electrical method is used to measure the peak junction temperature of power transistors. Based on the ex...It has been a scientific and technological problem in the field of microelectronics for several decades that the electrical method is used to measure the peak junction temperature of power transistors. Based on the excessive thermotaxis effect of low current, a novel electrical measurement method of the peak junction temperature is presented in this paper. The method is called the thermal spectrum analysis method of transistors, simply designated TSA （thermal spectrum analysis method）. Unlike the common method which uses a single measuring current, TSA uses multi-step currents to measure temperature-sensitive parameters. Based on the excessive thermotaxis effect of low current and the sub-transistor parallel model, the peak junction temperature and non-uniform property of junction temperature distribution are analyzed successfully.展开更多
基金Project of State Grid Corporation of China,Grant/Award Number:5700-202118195A-0-0-00。
文摘In urban power networks,a common practice is to bond numerous high-voltage cable circuits to a single grounding grid located in underground tunnels,primarily for reasons of installation convenience.In these situations,excessively high levels of sheath currents were often detected during routine inspections,but no electrical faults were found to be responsible.Previous publications ignored the currents flowing through the shared grounding points into the closed sheath loops of different circuits.In this paper,a mathematical model is established for the current circulating among sheath loops of different circuits,and the factors influencing the circulating current were analysed.The abnormal excessive sheath current is demonstrated to be an increase in the circulating current due to the combined effect of electromagnetic coupling and the shared grounding grid.The circulating current depends on the induced voltages which,in turn,depends on the cable layouts and load currents.The effects of these factors are evaluated in various scenarios.The increase of the circulating current is verified in a field case where four electrically healthy cable circuits sharing the same grounding points were found to have abnormal excessive sheath currents.
基金Project supported by the National Natural Science Foundation of China （Grant Nos. 61176119, 61171028, 51002081, and 61101018） and the Fundamental Research Funds for the Central Universities of China.
文摘Intrinsic Josephson junctions in misaligned T12Ba2CaCu208 thin film were fabricated on LaA103 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61176119, 61171028, 51002081, and 61101018)the Fundamental Research Funds for the Central Universities of China
文摘Intrinsic Josephson junctions in misaligned Tl2Ba2CaCu2O8 thin film were fabricated on LaAlO3 substrate. The temperature dependence of the critical current is investigated around liquid nitrogen temperature. In the current voltage characteristic, large voltage jump and lack of resistive branch are observed, which shows good consistency with the intrinsic Josephson junctions. By analyzing the large gap voltage in the curve, great suppression of the energy gap is found. Through discussing the temperature dependence of the gap voltage in liquid nitrogen temperature, it is shown that this phenomenon can be caused by the non-equilibrium quasiparticle injection. The temperature influence on the excess current also confirms the non-equilibrium effect.
基金Project supported by the National Natural Science Foundation of China (No.60476039)the Director Foundation of Institute of Microelectronics of Chinese Academy of Sciences (No.5408SA011001)
文摘It has been a scientific and technological problem in the field of microelectronics for several decades that the electrical method is used to measure the peak junction temperature of power transistors. Based on the excessive thermotaxis effect of low current, a novel electrical measurement method of the peak junction temperature is presented in this paper. The method is called the thermal spectrum analysis method of transistors, simply designated TSA （thermal spectrum analysis method）. Unlike the common method which uses a single measuring current, TSA uses multi-step currents to measure temperature-sensitive parameters. Based on the excessive thermotaxis effect of low current and the sub-transistor parallel model, the peak junction temperature and non-uniform property of junction temperature distribution are analyzed successfully.
