Finite-difference analysis of the atmosphere electric field distribution around a thunderstorm monomer
In this study, two-dimensional finite difference method (2D FDM) is adopted to simulate the electric field distribution around four typical thunderstorm monomers which have different heights, scales and charge distributions. This paper analyses the impact and its range of ground electric field caused by different thunderstorm monomers. This paper also gives a scientific definition and quantitative analysis for the detection range of ground atmospheric electric field meter which is a crucial tactical index. The results in this study have certain significance in theory and practical guidance for thunderstorm monitoring by using networking atmospheric electric field meters.
Finite-difference analysis of the potential distribution around an L-shape building base under the measurement of grounding resistance
For the first time, a three-dimensional finite difference method (3D FDM) is adopted to simulate the potential distribution during grounding resistance measurements around an L-shape building under different directions and electrodes arrangements. The results show that the distributions of zero potential region with different measurement points and measurement electrodes arrangements are strikingly different when using a straight-line-three-probes method. To obtain more accurate measurement results, scientific and suitable measurement point locations should be properly chosen for the grounding resistance measurement of L-shape buildings according to the surrounding conditions in practical measurements.
Measurement of earth-electrode resistance with particular reference to earth-electrode systems covering a large area
The method of measuring an earth-electrode resistance has been known for a number of years, but there are some aspects of the measurement which are not fully understood. In particular, there are difficulties which arise when the earth-electrode system is of large physical dimensions, e.g. that of a substation or power station. The simple method which is normally used cannot be applied directly for several reasons. It becomes very difficult to get outside the potential-gradient area of the system, owing to the great distance that it may extend. The auxiliary electrodes used must be placed as far away from the system as is practicable, and this involves the use of long leads, which may possess considerable self and mutual impedance. Again, with these large distances, the stray potential difference in the earth due, say, to leakage from the supply may be considerable, and the measuring equipment used must be capable of dealing with this. After an analysis of the basic factors involved, the paper describes a method of determining the resistance of a large electrode system and apparatus suitable for making the measurement.