Grounding electrode

The role of grounding electrodes is to drain fault currents effectively into the soil, and thereby to mitigate damage of installations of telecommunication systems and electrical power systems. Thus, the performance of such a system is influenced by the transient characteristics of its grounding electrodes. It is, therefore, important to study the transient characteristics of grounding electrodes. Recently, NBA methods have been applied successfully in analyzing the transient responses of grounding electrodes. 

Tanabe et al. [10] have studied the transient response of a horizontally-placed square-shape grounding electrode of 7.5 m x 7.5 m, buried 0.5 m in 

Resistivity profile in the dynamic model proposed by Liew and Darveniza [13] and employed by Ala et al. [12] for FDTD computations. 

When E at a soil-representing cell exceeds the critical electric field p begins 

This decreasing resistivity with time represents soil-ionization process. 

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Fig. 8. Magnetherm reactor central electrode, A secondary circuit, B grounding electrode, C refractory lining, D carbon lining, E primary material feed, F slag taphole to FeSi recovery, G vacuum line, H water spray ring, I condenser, cmcible, K trap, L filter, M and transformer, N.

The vertical tube (water-cooled) generator consists of two concentric tubes the outer of which is cooled with water and acts as the ground electrode. Feed gas is introduced into the top of the inner stainless steel tube (which serves as the high voltage electrode), exits at the bottom of the outer tube, flows upward through the aimular space (which contains the electric discharge), and emerges at the top of the outer tube into a product gas manifold. 

The following are a few types of grounding electrodes commonly used for the grounding of industrial installations, equipment grounding or small and medium-sized sub-stations. 

The choice of the metal (Section 22.4) for the grounding electrode will depend upon the corrosion factor of the soil. Btit all metals are equally good and possess a life span of 12 years and more. For a longer working life, the thickness of the electrode may be increased as discussed in Section 22.4.1. Gl being a more... 

Apparenlly Gl seems la be the best metal as a grounding electrode. But if part ol the zinc coaling of the metal is chipped due to poor coaling or to any other reason, the metal is rendered prone to rapid corrosion and erosion and may fail sviih passage of time. Some users therefore prefer to use bare MS conductor rather llian Gl. 

Highly corro.sive and is, therefore, less preferred compared to other metals, for underground connections or ground electrodes. For surface coitnections. however, w here it is less corrosive and highly conductive, compared to steel or steel alloys it is preferred... 

Calculation of Ground Electrodes Having a Longitudinal Resistance... 

PLATE 5. Propagating brush discharge (PBD) on charged layer initiated by grounded electrode. 

In order to establish safe values for velocity-diameter product, various studies have been made to determine the minimum liquid surface potential that will result in an incendive discharge in the presence of a grounded electrode. Studies reviewed in [8] showed that for credible charging conditions, liquids must be negatively charged to yield incendive bmsh discharges. The consensus has been that to avoid incendive discharges the maximum liquid... 

Grounding plates or lattices made of pure copper, while displaying good current-carrying capacities, do not provide a particularly low resistance due to the depth at which they can be buried. The third alternative is to bury lengths of copper tape around the installation. The use of reinforced concrete foundations for grounding electrodes has also recently been considered. 

Hori, T., M. Shibata, S. Okabe, and K. Hashizume, Super Ignition Spark Plug with Fine Center Ground Electrodes. SAE, 2003-01-0404, 2003. 

A critical issue in scaling up a process is the uniformity in deposition rate and material quality. In general, once the deposition rate is constant within 5% over the whole substrate area, the material properties also do not vary much. After fine-tuning the power and gas flow rates, operators still may face in homogeneity issues. These can be caused by local changes in temperature, RF voltage, and gas composition, due to various causes. As an example, it has been reported that improper attachment of the substrate to the grounded electrode results in a local decrease of the deposition rate [150, 151]. 

FIG. 6. Vertical cross section of the reaction chamber. Indicated are (I) the grounded electrode, (2) the RF electrode. (3) the dark space shield, (4) the gas supply. (5) the gas exhaust. (6) the position of the sample holder during deposition. (7) the position of the sample holder when loaded, and (8) the lift mechanism. 

The plasma potential is the maximum value with which ions can be accelerated from the edge of the sheath towards the substrate, located at the grounded electrode. This may cause ion bombardment, which may induce ion-surface interactions such as enhancement of adatom diffusion, displacement of surface atoms, trapping or sticking of incident ions, sputtering, and implantation see Section 1.6.2.1. 

In order to solve the differential equations, the boundary conditions of the potential and density profiles must be specified. The potential at the grounded electrode z = L, radius R) is set equal to zero. The potential at the driven electrode (z = 0) is set equal to... 

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