Analytical and numerical simulation techniques have been developed for the calculation of earth resistance/ impedance and to estimate the potential distribution in the vicinity of earth electrodes.However,very little ...Analytical and numerical simulation techniques have been developed for the calculation of earth resistance/ impedance and to estimate the potential distribution in the vicinity of earth electrodes.However,very little literature is available on experimental validation of these calculation techniques.To address this,a programme of experimental tests on various earth electrodes has been carried out at the lower water reservoir of a hydro pumped-storage power station in North Wales.In this paper,the earthing test facility at Dinorwig power station is described including the details of the experimental set up.The results from experimental tests on a 5 mX5 m earth grid,immersed in water and energized under ac,dc and impulse,are presented.The values of measured earth resistance/impedance and water surface potential distributions are compared with those obtained from analytical calculations and detailed numerical computer simulations.展开更多
One of the factors that affect the parameters of an underground cable is earth return path impedance.Pollaczek developed a formula for the case of one-layer(homogenous) earth.But in practice the earth is composed of s...One of the factors that affect the parameters of an underground cable is earth return path impedance.Pollaczek developed a formula for the case of one-layer(homogenous) earth.But in practice the earth is composed of several layers.In this study we develop a new formula for earth return path impedance in the case of a three-layer earth.To check the accuracy of the obtained results,a comparison has been made with the finite element method(FEM).A comparison between the results of the Pollaczek formula and results of the obtained formula for a three-layer earth has been made,showing that the use of the Pollaczek formula instead of the actual formula can cause serious errors.展开更多
文摘Analytical and numerical simulation techniques have been developed for the calculation of earth resistance/ impedance and to estimate the potential distribution in the vicinity of earth electrodes.However,very little literature is available on experimental validation of these calculation techniques.To address this,a programme of experimental tests on various earth electrodes has been carried out at the lower water reservoir of a hydro pumped-storage power station in North Wales.In this paper,the earthing test facility at Dinorwig power station is described including the details of the experimental set up.The results from experimental tests on a 5 mX5 m earth grid,immersed in water and energized under ac,dc and impulse,are presented.The values of measured earth resistance/impedance and water surface potential distributions are compared with those obtained from analytical calculations and detailed numerical computer simulations.
文摘One of the factors that affect the parameters of an underground cable is earth return path impedance.Pollaczek developed a formula for the case of one-layer(homogenous) earth.But in practice the earth is composed of several layers.In this study we develop a new formula for earth return path impedance in the case of a three-layer earth.To check the accuracy of the obtained results,a comparison has been made with the finite element method(FEM).A comparison between the results of the Pollaczek formula and results of the obtained formula for a three-layer earth has been made,showing that the use of the Pollaczek formula instead of the actual formula can cause serious errors.
