Grounding Resistance

Guide for measuring earth resistivity, ground impedance and earth stirface potentials of a ground system. Part I Normal measurements... 

Fig. 14-4 Circuit diagram for a low-resistance dc decoupling devices. (KE) insulated cable end sealing, (E) grounding installation, (1) resistance ( 10 mfl), (2) grounding side bar or short-circuit-resistant grounding switch.

The resistivity of the soil in any particular location will be a function of moisture content, soil temperature and presence of dissolved salts. At a site where climatic conditions vary considerably throughout the year, earth electrodes should be buried at a depth where such changes will not affect the resistivity. Grounding rods are generally made of copper bonded onto a steel core. The copper provides a good connection to earth and offers a high corrosion resistance, while the steel core gives the mechanical... 

W. C. Bloomquist, K. I. Owen and R. L. Gooch, High-resistance grounding power systems — why not IEEE Transactions on Industrial Applications. Vol. IA-12, Paper No.6, 1976. 

D. S. Baker, Charging current data for guesswork-free design of high-resistance grounded systems. IEEE Transactions on Industry Applications. Vol. IA-15, Paper No. 2, 1979. 

Electrical outlets shall be three-wire outlets withhigh-quality,low-resistance ground connections. Circuits should be clearly identified to correlate with labels in breaker panels. 

Electrical outlets shall be three-wire outlets withhigh-quality,low-resistance ground connections. Circuits should be clearly identified to correlate with labels in breaker panels. Some locations would need to be equipped with ground-fault interrupters (GFIs), such as where electrical connections are near sinks. 

Fig. 3.6.1. High resistance grounded scheme to avoid resonance overvoltages. 

B. Biidger, Jr. (1983). High Resistance Grounding, IEEE Transactions on Industiy Applications,... 

Resistance measuring instrument dc and ac (potential) Resistances (soil resistance, grounding resistance) 0 - 999 kQ 1 kQ... 

The low leakage load of a good pipe coating can be nullified by contact with low-resistance grounded installations. Such contacts occur at custody transfer stations with electrically actuated valves, tubular annuli at easings and concrete constructions, at interconnection points and valve supports, and at foreign lines and cables. Such contacts are to be avoided by eonstnictive measures. 

FIGURE 10.214 High-resistance grounded wye power system. (Courtesy of Intertec Publishing. After [5].)... 

Resistance-grounded A circuit or system grounded for safety through a resistance, which limits the value of the current flowing through the circuit in the event of a fault. 

Resistance grounds—The neutral wire is connected to ground through a high resistance at a transformer. 

Although these data establish the usefulness of silylated polyazamide sizes compared to conventional silanes, they also point out the limitations of such systems relative to commercial sizes. In the case of reinforced PBT, neither simple silane sizes—lubricant-modified nor polyazamides—can compete effectively with the sophisticated chemistry of modern commercial sizes either on strength or on impact and environmental resistance grounds. 

Federal regulations require coal mine power s5rstems to be resistance grounded. (Resistance grounding and other forms of grounding are discussed later in this chapter.) For this reason, the secondary of the power transformer is usually wye-connected to provide a convenient power-system neutral point. The neutral grounding resistor is connected between the transformer s neutral point and the safety ground. 

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