The soil ionization gradient associated with discharge of high currents into concentrated electrodes

Mousa, A.M.

doi:10.1109/61.311195

Cited by 230 publications

(88 citation statements)

References 17 publications

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“…Electrical breakdown of the soil is initiated by ionization of the air trapped in the voids of the soil. The ionization gradient of the soil is always less than that of air and it is reduced when the moisture content is high [16]. The time to initiation of ionization is mainly dependent on the amplitude of impulse voltage, the moisture content, and the type and grain size of soil.…”

Section: Breakdown Voltage -Time-lag Characteristicsmentioning

confidence: 98%

“…Indeed, it allows both material and cost savings while installing grounding systems for lightning protection. To the best of our knowledge, many studies on characteristics of transient impedance of grounding systems stressed by high impulse currents have been conducted [15,16]. However, data for soil discharges are still insufficient and required.…”

Section: Introductionmentioning

confidence: 99%

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Discharge Characteristics in Soils Subjected to Lightning Impulse Voltages

Kim¹,

Yoo²,

Lee³

2016

Journal of Electrical Engineering and Technology

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-In this paper, we present experimental results of the soil discharge characteristics as a function of moisture content when a 1.2/50-㎲ lightning impulse voltage is applied. For this study, laboratory experiments were carried out based on factors affecting the transient behavior in soils. The electrical breakdown voltages in soils were measured for a 0-6% range of moisture content for sand and a 0 -4% range of moisture content for gravel. A test cell with semi-spherical electrodes buried face-to-face in the middle of a cylindrical container was used. The distance separating the electrodes is 100 mm. As a result, the time-lag to breakdown in soils decreases as the amplitude of applied voltage increases. The time-lag to initiation of ionization streamer is decreased, with an increase in the moisture content. However, the formative time-lag is rarely changed. The behavior of soil discharges depend not only on the type of soil and its moisture content but also on the amplitude of the impulse voltage. When the test voltage is applied repeatedly, electrical breakdown occurs along different discrete paths, leading radially away from the injected electrode. i.e., the fact that the ionization streamers propagate in different paths from shot to shot was observed.

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Section: Breakdown Voltage -Time-lag Characteristicsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Discharge Characteristics in Soils Subjected to Lightning Impulse Voltages

Kim¹,

Yoo²,

Lee³

2016

Journal of Electrical Engineering and Technology

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“…Such experiments have the advantage of controlled conditions; however, there is uncertainty as to whether they can be reliably extrapolated to replicate full-scale grounding system behaviour. Several models that have been proposed *Address correspondence to this author at the High Voltage Energy Systems Group, School of Engineering, Cardiff University, the Parade, Cardiff CF24 3AA, UK; Tel: +44 (0)29 20875351; Fax: +44 (0)29 20874716; E-mail: Haridn@Cardiff.ac.uk to account for soil ionisation and non-linear thermal effects [7][8][9][10][11] rely on these experiments for validation. However, field experiments on full-scale grounding systems offer a more realistic way of validating model computations because of their unbounded environment and non-uniform soil conditions.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Impulse Characteristics of Transmission Line Tower Footings

Harid¹

2012

JLR

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Abstract:Understanding the impulse response of tower grounding systems is a key factor in the determination of the lightning performance of transmission lines and the safety voltages near high voltage towers. This paper reports the results of an experimental study on the impulse characteristics of full-scale transmission line tower footings. The ground potential distribution both at the ground surface and below ground was examined under impulse currents and variable-frequency AC currents. Prospective impulse step and touch voltages were determined by measurement of the ground surface potential distribution near the tower base. The behaviour of the impulse resistance of the tower footings under highmagnitude impulse currents was investigated. The non-linear characteristics of the impulse resistance with peak current are demonstrated for the entire tower base and for single tower footings. The soil ionisation inception is found to be dependent on the rate of rise of applied current. The dynamic impulse resistance was used to describe the dynamics of soil ionisation.

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“…Soil breakdown phenomenon occurs when the high impulse current discharges into the earth through the grounding conductors [1][2][3][4][5]. Due to the soil breakdown, the resistance of the soil and consequently the peak voltage response of the grounding electrode decrease.…”

Section: Introductionmentioning

confidence: 99%

“…Due to the heating process, the resistivity of the heated water decreases, which in turn causes the resistivity of the bulk soil and consequently reduces the grounding electrode resistance [6][7][8]. In the soil ionisation process, the electric field enhancement in air voids enclosure among the soil grains, causing the soil breakdown occurrence [5,[9][10][11]. Since the resistance of the ionized air is much smaller than the resistance of the soil grains, the equivalent soil resistance decreases.…”

Section: Introductionmentioning

confidence: 99%

A critical review on soil ionisation modelling for grounding electrodes

Mokhtari

Abdul‐Malek

Gharehpetian

2016

Archives of Electrical Engineering

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Grounding electrode resistance non-linearly changes under impulse conditions due to soil ionisation phenomenon. Several models have been proposed to model soil ionisation for grounding electrodes applications. However, to date, there is yet an attempt made to compile all these works into a comprehensive review article. Therefore, this paper is written with the objective of summarizing all related works in this field as a onestop reference. With reference to the literature, this paper is written to summarize the working principles of the soil ionisation models as well as the accuracy and performance analysis of the models. This paper, particularly highlights the deficiencies of the available models in terms of accuracy and performance. This knowledge will contribute to the development of a new accurate and efficient soil ionisation model.

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The soil ionization gradient associated with discharge of high currents into concentrated electrodes

Cited by 230 publications

References 17 publications

Discharge Characteristics in Soils Subjected to Lightning Impulse Voltages

Discharge Characteristics in Soils Subjected to Lightning Impulse Voltages

Experimental Investigation of Impulse Characteristics of Transmission Line Tower Footings

A critical review on soil ionisation modelling for grounding electrodes

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