Simulation study of lightning fault waveforms influenced by the arc quenching properties of wooden distribution line poles

Abstract With an ever increasing emphasis on reliability of supply, improvement in the lightning performance of distribution lines is required. The arc quenching properties of wooden distribution line poles during lightning strikes are an important factor in the reduction of switchgear operation, hence outages. Measurements were conducted on a 22 kV distribution line and it was suspected, in some cases, that direct lightning strikes to the line did not cause switchgear operation. Distribution lines predominantly use wooden poles with a specific configuration which incorporates a 'wooden' spark gap. This paper provides background to the basic configuration of a typical distribution line and the processes which govern the electric arc. A simulation using a dynamic arc model shows that field measured lightning overvoltages on a distribution line are reproducible through system modelling. The simplistic dynamic arc model developed is sufficiently accurate to describe a set of arcs in a larger system such as a distribution line

Ship propulsion using wind, batteries and diesel-electric machinery - Dimensioning of a propulsion system using wind, batteries and diesel-electric machinery

Wind energy is a resource that is not used to any great extent in the shipping industry since the advent of the internal combustion engine in the 1920s. Since then, wind power is utilized at sea in less extent until recent years. In this report, the authors will investigate how a ship that runs on wind power can reduce its bunker consumption, both directly and indirectly through wind energy. Directly is how the wind energy can relieve the engines on board and indirectly how a ship, with the help of wind assistance, can have smaller equipment on board to decrease the fuel consumption. The ship model for this report has a diesel-electric machinery and batteries that will help reduce consumption. To carry out this work the authors created a numerical model ship in MATLAB that imitates a Panamax tanker. This ship was installed with a Flettner rotor, a kite and a wind turbine in three different scenarios to see how they can reduce consumption. According to the mathematical values the Flettner rotor was the most effective at utilizing wind power and could save up to 9038 US dollar each day. However, this report has limited itself to look at the ship and its propulsion under conditions with ideal wind direction

The anodic dissolution of magnesium in aqueous solutions

The anodic dissolution of magnesium was studied in MgCl2-KC1 and MgBr2-KBr mixtures at 25, 40, and 55 °C. The parameters of the study were current density, concentration of magnesium ion, and temperature. The concentration of magnesium ions was varied from 0.001 to 1 N holding the ionic strength constant at 1.5. The weight loss of magnesium from the electrode during electrolysis was determined by weighing the electrode both before and after electrolysis. The current was measured with a sensitive milliammeter. The range of the current densities was varied from 0.001 to 0.1 amps·cm-2. The apparent valence of magnesium ions going into solution was determined. The following was concluded: The apparent valence of magnesium dissolving anodically is decreased rapidly as current density is increased at current densities below 0.03 amps·cm-2. From 0.03 to 0.1 amps·cm-2, the apparent valence decreases slowly with increasing density. The effect of concentration of magnesium ions and temperature on the apparent valence of magnesium dissolving anodically in KCl-MgCl2 and KBr-MgBr2 mixtures is small. The apparent valence of magnesium dissolving in 1 N MgCl2 and MgBr2 solutions has a much more pronounced temperature and current density effect at low current densities. The apparent valence-current density plots for the anodic dissolution of magnesium can be separated into two regions where there exists linear relationships between them. The potential measurements of magnesium dissolving anodically under similar conditions led to the following conclusions: The overpotential is very slightly affected by temperature and concentration, except in 1 N MgCl2 and MgBr2 solutions. The electrode is not appreciably polarized at current densities below 0.03 amps·cm-2. Above 0.03amps·cm-2 the electrode polarizes rapidly indicating passivation. On the basis of the above, it is concluded that the behavior of magnesium is consistent with the model proposed by Sun in which the anodic dissolution consists of three simultaneous processes, an electrochemical reaction, local corrosion, and disintegration. The deviation of the valence of the magnesium ions from the normal valence, i.e., deviation from Faraday\u27s law, is accounted for by local corrosion and disintegration. A mathematical model is derived that gives the observed influence of current density --Abstract, pages iii-iv

The anodic behavior of zinc in aqueous salt solutions

The increasing demand for protective metals as coatings and non-corrosive alloys has caused extensive research on the fundamental behavior of metals in corrosive media. The problem of controlling the destructive process of metallic corrosion still exists and becomes urgent in this space age. The desirablity of metals such as beryllium, magnesium, and zinc in air frame and space structural units, because of their high strength to weight ratio, has been responsible for the considerable progress in their technology in recent years. The basic mechanism of the anodic dissolution of metals such as zinc, cadmium, and magnesium in salt solution is not completely known. Many mechanisms have been proposed by different investigators but evidence is still lacking which would allow one to draw reliable conclusions and to explain the discrepanies which often arise between coulometric data and the weight loss of the metal electrodes in certain salt solutions. The study of the influence of anions as well as cations on the anodic behavior of zinc undergoing dissolution might give an insight into the basic mechanism of metallic corrosion and the type of substances needed for corrosion inhibition. The purpose of this investigation was to obtain a mechanism for the anodic dissolution of zinc that would relate the rate of dissolution, the anodic current density, the influence of anions, and other parameters to the observed behavior --Introduction, pages 1-2

Electrochemical/Electroflotation Process for Dye Wastewater Treatment

The use of dyes has become very significant across various industries such as textiles, paper, and clothing. The organic chemical composition of dyes is a major concern when discharging wastewater not only into the environment, but also within wastewater treatment plants. Dye effluent consists of high chemical oxygen demand (COD) and also color, components that require treatment before discharge. As a result, federal legislation has required industries that discharge high components in wastewater to undergo treatment within the plants. Within literature, authors have considered various biological, physical, and chemical methods of treating dye wastewater. Recently, electrocoagulation/electroflotation (ECF) has been an additional method of treatment that has been considered for the treatment of dye wastewater. Two separate studies are considered. First, Acid Yellow 11 (AY11) at a concentration of 25 mg/L (by weight) underwent treatment from three different coagulants (Alum, Ferric Sulfate, and Ferric Chloride) , under three different strengths (5 mg/L, 10 mg/L, and 15 mg/L), and two different initial pH considerations (4 and 7) for the purpose of analyzing color removal. Following the study, the results were collaborating into a response surface methodology, developing an equation for the three different coagulants. In addition, a Box-Behnken design has been setup for the purpose of considering the effects of pH, dye concentration, dye type, coagulant type and strength on the efficiency of electrocoagulation. These values will be analyzed using statistical analysis, along with toxicity study done on the effectiveness of removing toxic contaminants from the wastewater. Finally, a photo-oxidation study was completed on Acid Orange 7 (AO7) synthetic dye wastewater for the purpose of determining the effects of photo-oxidation based on dye concentration, catalyst type and dose. Langmuir-Hinshelwood coefficients were developed based on the results of this experimen

Electrochemical/Electroflotation Process for Dye Wastewater Treatment

The use of dyes has become very significant across various industries such as textiles, paper, and clothing. The organic chemical composition of dyes is a major concern when discharging wastewater not only into the environment, but also within wastewater treatment plants. Dye effluent consists of high chemical oxygen demand (COD) and also color, components that require treatment before discharge. As a result, federal legislation has required industries that discharge high components in wastewater to undergo treatment within the plants. Within literature, authors have considered various biological, physical, and chemical methods of treating dye wastewater. Recently, electrocoagulation/electroflotation (ECF) has been an additional method of treatment that has been considered for the treatment of dye wastewater. Two separate studies are considered. First, Acid Yellow 11 (AY11) at a concentration of 25 mg/L (by weight) underwent treatment from three different coagulants (Alum, Ferric Sulfate, and Ferric Chloride) , under three different strengths (5 mg/L, 10 mg/L, and 15 mg/L), and two different initial pH considerations (4 and 7) for the purpose of analyzing color removal. Following the study, the results were collaborating into a response surface methodology, developing an equation for the three different coagulants. In addition, a Box-Behnken design has been setup for the purpose of considering the effects of pH, dye concentration, dye type, coagulant type and strength on the efficiency of electrocoagulation. These values will be analyzed using statistical analysis, along with toxicity study done on the effectiveness of removing toxic contaminants from the wastewater. Finally, a photo-oxidation study was completed on Acid Orange 7 (AO7) synthetic dye wastewater for the purpose of determining the effects of photo-oxidation based on dye concentration, catalyst type and dose. Langmuir-Hinshelwood coefficients were developed based on the results of this experimen