In this paper,the electrical fields along the insulator surface under different scenarios,such as asymmetric pollution on top/bottom surface,and uneven circumferential distribution of surface pollution,have been calcu...In this paper,the electrical fields along the insulator surface under different scenarios,such as asymmetric pollution on top/bottom surface,and uneven circumferential distribution of surface pollution,have been calculated with finite element method for field simulation.Tests on artificial pollution insulators are conducted to study the 50% withstand voltage U50 of artificial pollution suspension insulators under different NSDD(non-soluble deposit density)and asymmetric pollution on the top/bottom surface,and study the change of leakage current with air humidity under different voltage and different ESDD(equivalent salt deposit density).The result shows that asymmetric top/bottom surface pollution has a greater impact on the insulator electrical field distribution,and the leakage current will jump under low air humidity,if had large ESDD,which has practical meanings to the anti-pollution design of the transmission line under different pollution levels across the country.展开更多
This paper presents the results of the study concerning to the leakagecurrent behaviour on artificially polluted ceramic insulator surface. From the present study it wasobserved that there is a reasonably well-defined...This paper presents the results of the study concerning to the leakagecurrent behaviour on artificially polluted ceramic insulator surface. From the present study it wasobserved that there is a reasonably well-defined inception of current i.e. scintillations at afinite voltage, The corresponding voltages for extinction of the current are in the range of 0.8 kVto 2.1 kV. Obviously, the dry band formed in the immediate vicinity of the pin prevents smoothcurrent flow as the voltage rises from zero. Only when the voltage is adequate it causes a flashoverof the dry band and current starts flowing. As is common in similar current extinction phenomena,here also, the extinction voltages are significantly lower than the inception voltages. Further, thevoltage-current curves invariably show hysteresis - the leakage currents are lower in the reducingportion of the voltage. This is obviously due to drying of the wet pollutant layer therebyincreasing its resistance. It is believed that this is the first time that such a directquantitative evidence of drying in individual half cycles is experimentally visualized.展开更多
Both the ceramic and the composite insulators have their own advantages and disadvantages when compared with each other. It is a reasonable idea to combine their merits together to design a novel insulator. The key me...Both the ceramic and the composite insulators have their own advantages and disadvantages when compared with each other. It is a reasonable idea to combine their merits together to design a novel insulator. The key measure of the novel insulator suggested in this paper is to add an annular metal sheet coated with high temperature vulcanisation (HTV) silicone rubber (SIR) at the base of the traditional ceramic insulator cap. The HTVSIR covering on the exterior of the metal sheet can lengthen the creepage distance. The metal sheet can uniform the electric stress, reduce its maximum value and modify its direction on one insulator unit and acts as equalizing ring on an insulator string. The factors stated above are the main reasons why the novel insulator has better insulating performance, including lower leakage current and flashover voltage, especially under polluted conditions. Simultaneously, the novel insulator can overcome the disadvantages of the ordinary remedies which have been widely used to improve the performance of ceramic insulators against pollution. The experimental results obtained in the laboratory were in good agreement with the theoretical analysis and demonstrated the novel insulator's effectiveness.展开更多
In this paper, the impact of the conductivity and the distribution of pollution on the behavior of the high voltage insulator cap and pin 1512L, artificially polluted is described. An experimental model in form of a d...In this paper, the impact of the conductivity and the distribution of pollution on the behavior of the high voltage insulator cap and pin 1512L, artificially polluted is described. An experimental model in form of a disc is proposed. This experimental model reproduces the real model which is the 1512L insulator. Besides, a comparative study is presented. For this comparative study, different solutions are adopted to s`imulate the pollution (containing NaCl + distilled water) that has different conductivities for a discontinuous distribution of the pollution on the insulator under an AC voltage. Furthermore, the influence of the pollution on the flashover voltage and the leakage current is studied. Finally, the behavior of real and experimental model of the insulator is investigated.展开更多
基金Project Supported by Key Technology Research Programof SGCC(SGSC[2005]115)
文摘In this paper,the electrical fields along the insulator surface under different scenarios,such as asymmetric pollution on top/bottom surface,and uneven circumferential distribution of surface pollution,have been calculated with finite element method for field simulation.Tests on artificial pollution insulators are conducted to study the 50% withstand voltage U50 of artificial pollution suspension insulators under different NSDD(non-soluble deposit density)and asymmetric pollution on the top/bottom surface,and study the change of leakage current with air humidity under different voltage and different ESDD(equivalent salt deposit density).The result shows that asymmetric top/bottom surface pollution has a greater impact on the insulator electrical field distribution,and the leakage current will jump under low air humidity,if had large ESDD,which has practical meanings to the anti-pollution design of the transmission line under different pollution levels across the country.
文摘This paper presents the results of the study concerning to the leakagecurrent behaviour on artificially polluted ceramic insulator surface. From the present study it wasobserved that there is a reasonably well-defined inception of current i.e. scintillations at afinite voltage, The corresponding voltages for extinction of the current are in the range of 0.8 kVto 2.1 kV. Obviously, the dry band formed in the immediate vicinity of the pin prevents smoothcurrent flow as the voltage rises from zero. Only when the voltage is adequate it causes a flashoverof the dry band and current starts flowing. As is common in similar current extinction phenomena,here also, the extinction voltages are significantly lower than the inception voltages. Further, thevoltage-current curves invariably show hysteresis - the leakage currents are lower in the reducingportion of the voltage. This is obviously due to drying of the wet pollutant layer therebyincreasing its resistance. It is believed that this is the first time that such a directquantitative evidence of drying in individual half cycles is experimentally visualized.
文摘Both the ceramic and the composite insulators have their own advantages and disadvantages when compared with each other. It is a reasonable idea to combine their merits together to design a novel insulator. The key measure of the novel insulator suggested in this paper is to add an annular metal sheet coated with high temperature vulcanisation (HTV) silicone rubber (SIR) at the base of the traditional ceramic insulator cap. The HTVSIR covering on the exterior of the metal sheet can lengthen the creepage distance. The metal sheet can uniform the electric stress, reduce its maximum value and modify its direction on one insulator unit and acts as equalizing ring on an insulator string. The factors stated above are the main reasons why the novel insulator has better insulating performance, including lower leakage current and flashover voltage, especially under polluted conditions. Simultaneously, the novel insulator can overcome the disadvantages of the ordinary remedies which have been widely used to improve the performance of ceramic insulators against pollution. The experimental results obtained in the laboratory were in good agreement with the theoretical analysis and demonstrated the novel insulator's effectiveness.
文摘In this paper, the impact of the conductivity and the distribution of pollution on the behavior of the high voltage insulator cap and pin 1512L, artificially polluted is described. An experimental model in form of a disc is proposed. This experimental model reproduces the real model which is the 1512L insulator. Besides, a comparative study is presented. For this comparative study, different solutions are adopted to s`imulate the pollution (containing NaCl + distilled water) that has different conductivities for a discontinuous distribution of the pollution on the insulator under an AC voltage. Furthermore, the influence of the pollution on the flashover voltage and the leakage current is studied. Finally, the behavior of real and experimental model of the insulator is investigated.
