Impulse Characteristics of Tower Grounding Devices Considering Soil Ionization by the Time-Domain Difference Method

Validity of Improved MTL for Effective Length of Counterpoise Wires under Low and High-Valued Lightning Currents

“…Consider a horizontal electrode under high-valued impulse current so that ionization phenomenon is taken place as shown in figure 2(a). This phenomenon is conventionally modelled as gradually increasing radius as shown in figure 2(b) in which the electrode is divided into N segment of length and equivalent radius [8]. Then, the sending and receiving voltage and current for each segment is defined as shown in figure 3(a).…”

“…There are a number of approaches for analysis and design of grounding systems including the frequency-domain approaches [3][4][5] for only-dispersive soils, and the timedomain approaches [6][7][8] for only-ionized soils. In the soils where ionization and dispersion of soils are simultaneously occurred, the mixed frequency-time domain approaches [9][10][11][12][13][14][15] should be used.…”

Comprehensive formulae for effective length of multiple grounding electrodes considering different aspects of soils: Simplified multiconductor transmission line‐intelligent water drop approach

“…To this aim, transient voltage of the grounding systems (defined as the voltage of point of the injected current to a point at infinite) should be first correctly computed. Hence, to compute this quantity a number of numerical approaches in time domain, frequency domain, and mixed time‐frequency domain have been proposed . In only‐ionized soils, time domain approaches are usually preferable, whereas in only‐dispersive soils, the frequency‐domain techniques are more appealing .…”

“…Hence, to compute this quantity a number of numerical approaches in time domain, frequency domain, and mixed time‐frequency domain have been proposed . In only‐ionized soils, time domain approaches are usually preferable, whereas in only‐dispersive soils, the frequency‐domain techniques are more appealing . To consider two effects simultaneously, frequency domain approaches in combining with circuit theory have been proposed.…”

Observation and analysis of the sparkover around grounding electrode under impulse current

“…The rationality and accuracy of a simulation model for grounding electrode under impulse current depends on whether it reflects the sparkover process well or not. A widely used method is based on critical breakdown electric field E c [3–5]. The resistivity of those areas where the electric field exceeds E c is set to be very low close to zero.…”