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An assessment of the economic benefits of using fuel cells is presented. A calculation of the cost of electricity generated from a fuel-cell installation, and a determination of the amount of profit that might result from an installation is given. A break even and sensitivity analysis is also conducted to determine what goals need to be achieved to make fuel cells competitive with conventional power generation sources. The study was performed using a graphical user interface programmed in MATLAB. Index Terms--Economic evaluation, fuel cells, graphical user interface (GUI).

Multiple inclined rods give better performance at locations where the space for installing the grounding electrodes is limited. Formulas to determine the ground resistance and impulse ground impedance of the inclined rods have been developed and are presented in this paper. For grounding at wood pole lines vertical conductors run along the length of the pole that is in the soil prove to be a better grounding arrangement compared to the commonly used butt wire wrap. Formula to calculate the ground resistance of such an arrangement is also given in this paper.

Limited thickness of the surface layer of gravel in a substation yard decreases the ground resistance of the foot from its value for the infinite thickness of the surface layer, by reduction factor C. The foot is usually represented by an equivalent circular plate of radius 8 cm. This paper presents method and equations to accurately determine the reduction factor for the circular plate. The equations are valid for any depth of the upper layer. The data presented in the from of graphs. A simple empirical equation for determining the value of C is also presented. Keywords: Footing Resistance, Grounding, Safety, Body current, Substations.

The ground resistance of the foot is affected by the limited depth of the gravel layer usually spread over the surface of the soil in substation yards. Equations and graphs given in IEEE Standard 80 to determine this ground resistance are not accurate and give conservative results. This paper presents more accurate equations and graphs for determining the ground resistance of the foot in a substation having a thin surface layer of gravel. Analysis has been made with two models of the foot. In one model the foot is represented by an equivalent circular plate and in the other by an equivalent rectangular plate. Results obtained with these two models and with the IEEE Standard 80 method have been compared.

The ground resistance of the feet is an important factor that determines the current flow in the body of a person exposed to dangerous touch voltage in a high voltage switchyard. It is modified by the proximity of the two feet and the presence of the energized grounding grid below the feet. Based on the Thevenin approach a general method for determining the effective ground resistance of the feet that takes into account the two above mentioned modifying factors is presented in this paper. The proposed method is verified with the help of analog model study. Results show that in most practical situations the effect of the two modifying factors can be ignored. The situations where it is necessary to consider these factors are also identified.

A fault current at a substation injected into a grounding grid that is intertied with the grounding grid of another station with buried conductors, is dissipated to the ground by the grids at both the stations and by the intertie. This paper presents a direct, simple and easy to use approximate method to determine the ground resistance of the system as seen from the station where the current is injected and the ground potential rise at both the stations. A comparison of the results obtained with the approximate method and from the accurate method has been made. An expression for the length constant of the intertie as a function of the resistivity of the soil has been derived. This concept is useful to estimate the distance beyond which the two grids intertied with buried conductors will have negligible effect on each other.

This paper reports the development of a computer approach for evaluating the general performance of stand-alone wind/photovoltaic generating systems. Simple models for different system components are developed, integrated, and used to predict the behavior of generating systems based on available wind/solar and load data. The model is useful for evaluating the performance of stand-alone generating systems and gaining a better insight in the component sizes needed before they are built. Simulation results are presented for performance evaluation of a stand-alone generating system that has been previously designed to supply the average power demand of a typical residential house [1]. An electric water heater model is used as a dump load, and the excess available wind/solar-generated power is used to heat the water. The heated water is used as the inlet water to the main house water heater, which is assumed to be nonelectric. It is shown that this strategy can be effective in reducing the amount of fuel used by the main residential water heater. Index Terms--Computer modeling, electric water heater dump load, wind/PV generation.