In this paper, the influence of working electrolyte on high-frequency electrical performance of wet tantalum capacitors is studied. Emphasis is especially put on the study of the contribution of depolariser in reducin...In this paper, the influence of working electrolyte on high-frequency electrical performance of wet tantalum capacitors is studied. Emphasis is especially put on the study of the contribution of depolariser in reducing Equivalent Series Resistance(ESR). According to the theory of depolarization in electrochemistry and the theory of cathode capacitance of electrolytic capacitor, different kinds of depolarisers are added separately into the foregone electrolyte. Then capacitors are assembled with tantalum cores dipped with the compounded electrolytes. The best depolariser and its concentration in the whole electrolyte could be selected according to the test results of the capacitance and ESR of the capacitors. The results of our experiment show that depolariser Fe 2(SO 4) 3 used in working electrolyte of 100 V/100 μF wet tantalum capacitors can help to obtain lower ESR and higher capacitance at frequency from 0.1 kHz to 100 kHz.展开更多
The±200 kV direct current(DC)cables of the Zhoushan Transmission Project were targeted,and crosslinked polyethylene(XLPE)insulation samples were prepared from faulty and spare cables.Samples were tested for oxida...The±200 kV direct current(DC)cables of the Zhoushan Transmission Project were targeted,and crosslinked polyethylene(XLPE)insulation samples were prepared from faulty and spare cables.Samples were tested for oxidation induction period,Fourier transform infrared spectroscopy,differential scanning calorimetry,thermally stimulated depolarisation current,space charge and DC dielectric strength.The evolution of performance parameters was analysed,and the insulation ageing characteristics of onsite operating DC cables were deduced.The results show that compared with spare cables,the carbonyl index of operating cables decreases,the crystallinity increases and DC dielectric strength increases slightly.It is inferred being related to the reduced content of antioxidants and crosslinking by-products and improved molecular chain and crystal microstructure of XLPE insulation.It is suggested that the insulation ageing of high voltage DC XLPE cable is divided into two stages.In the early stage,the secondary crosslinking and recrystallisation processes are dominant,and the thermal and electric effects make the material properties basically stable or even slightly improved.In the middle and later stage,the thermal oxygen reaction is dominant,the microstructure of the material is destroyed,with a large number of macromolecular chains broken and some crystalline regions transformed into amorphous ones,and the insulation properties degraded significantly.展开更多
文摘In this paper, the influence of working electrolyte on high-frequency electrical performance of wet tantalum capacitors is studied. Emphasis is especially put on the study of the contribution of depolariser in reducing Equivalent Series Resistance(ESR). According to the theory of depolarization in electrochemistry and the theory of cathode capacitance of electrolytic capacitor, different kinds of depolarisers are added separately into the foregone electrolyte. Then capacitors are assembled with tantalum cores dipped with the compounded electrolytes. The best depolariser and its concentration in the whole electrolyte could be selected according to the test results of the capacitance and ESR of the capacitors. The results of our experiment show that depolariser Fe 2(SO 4) 3 used in working electrolyte of 100 V/100 μF wet tantalum capacitors can help to obtain lower ESR and higher capacitance at frequency from 0.1 kHz to 100 kHz.
文摘The±200 kV direct current(DC)cables of the Zhoushan Transmission Project were targeted,and crosslinked polyethylene(XLPE)insulation samples were prepared from faulty and spare cables.Samples were tested for oxidation induction period,Fourier transform infrared spectroscopy,differential scanning calorimetry,thermally stimulated depolarisation current,space charge and DC dielectric strength.The evolution of performance parameters was analysed,and the insulation ageing characteristics of onsite operating DC cables were deduced.The results show that compared with spare cables,the carbonyl index of operating cables decreases,the crystallinity increases and DC dielectric strength increases slightly.It is inferred being related to the reduced content of antioxidants and crosslinking by-products and improved molecular chain and crystal microstructure of XLPE insulation.It is suggested that the insulation ageing of high voltage DC XLPE cable is divided into two stages.In the early stage,the secondary crosslinking and recrystallisation processes are dominant,and the thermal and electric effects make the material properties basically stable or even slightly improved.In the middle and later stage,the thermal oxygen reaction is dominant,the microstructure of the material is destroyed,with a large number of macromolecular chains broken and some crystalline regions transformed into amorphous ones,and the insulation properties degraded significantly.
