Chen Jiaqing

Analysis of transient grounding resistance under pulsed discharging current

This paper presents numerical analysis of the transient grounding resistance of the grounding conductor under pulsed discharging current using the FDTD method; and analyses the influence of its size, buried depth and the ground conductivity. In the end, methods for reducing transient grounding resistance and discharging faster are discussed.

Influence of Parameters of the Transient Grounding Model on Numerical Analysis and Experimental Verification

This paper discussed the influence of the parameters of the transient grounding model on numerical analysis using FDTD method; some useful results are given and verified by the experiment.

Influence of the grounding Electrode on transient grounding resistance under pulsed discharging current

The influence of the variations of grounding electrode in volume, surface area, conductivity and permeability on transient grounding resistance (TGR) under pulsed discharging current is analyzed with FDTD method in this paper. From the computation results, some useful conclusion can be got as follow: the grounding electrodes with the same surface area have nearly the same TGR. For the grounding electrodes with the same volume, the larger the surface area is, the smaller is the TGR. Nonmetal grounding electrode, whose conductivity is high enough, has the same discharging effect as the metal. The permeability of grounding electrode has little influence on TGR

Influence of outside environment on transient grounding resistance under pulsed discharging current

This paper analyzes the influence of outside environment of the grounding conductor, including the interference source and the ground, on transient grounding resistance (TGR) under pulsed discharging current by using FDTD method. The results show that (1) TGR has bigger peak value and longer steady time when fast rising edge interference pulse acting on the grounding conductor than slow rising edge interference pulse; (2) when the layered soil is met, the grounding conductor should be buried in the soil which has bigger conductivity and not be in the neighboring of the layered boundary; (3) the locally improved soil has remarkable effect on the decrease of TGR, especially the expansion of the range of locally improved soil, but the influence of that on TGR is stepping down along the farther increasing of its conductivity when its range is fixed.

FDTD analysis of the potential distribution in reinforced steel frames of a building under direct lightning stroke

The back flashover caused by lightning could make serious damage to electrical and electronic systems within the structure under lightning stroke, and international lightning protection codes pay great attention to the problem. In this paper, FDTD method is adopted to calculate waveforms of the transient potential rise in the steel structure when the roof corner struck by lightning. Moreover, the peak distribution of the potential on each floor is discussed. The conclusions will provide theoreticcal reference for EMC design inside a building.

Experimental investigation of transient grounding resistance characteristics on the radialized grounding electrode

The characteristics of transient voltage, current and grounding resistance of two kinds of radialized grounding electrodes were investigated based on field measurements. Each kind of grounding electrode was made of reinforcing steel bars with diameter of 10 mm, and had the same total length of 16 m, and were buried horizontally at the depth of 0.6 m from the ground surface. The star-shape grounding electrode was composed of 8 reinforcing steel bars; The cross-shape one was composed of 4 reinforcing steel bars. A transient discharge from a high-voltage pulse generator was applied at the center of the grounding electrode to observe transient voltage and current on it. The measured waveforms were synchronously recorded, the transient grounding resistance was calculated and analyzed. From the experiment results, we can see the obvious capacitive characteristic on the star-shape grounding electrode. We can also see the accordance between the stable value of TGR and the theoretic value of power frequency ground resistance.

Experimental Investigation of Transient Grounding Resistance Characteristics on a Spokewise Grounding Electrode

The characteristics of transient voltage, current and grounding resistance of a spokewise grounding electrode is investigated based on field measurements. The grounding electrode is composed of 8 reinforcing steel bars with diameter of 10 mm, every bar with the length of 2 m, and is buried at the depth of 0. 6 m from the ground surface. A pulse discharge from a high-voltage capacitor is applied at the center of the grounding electrode to observe transient voltage and current on it. The measured results are illustrated, the transient grounding resistance is calculated and analyzed.