1,720,998 research outputs found
Harnessing the Concept of Infinity in Power Systems Analysis: From Abstraction to Practicality
Full text linkIn the field of power systems, the concept of infinity plays a crucial theoretical role, enabling the depiction of extreme limits as quantities approach very large values. This theoretical model simplifies complex issues and encourages innovative problem-solving strategies for engineers. This article delves into the diverse role of infinity as a theoretical construct within power systems, illustrating how this abstraction aligns with the practical application of engineering principles. The discussion covers topics, such as ground potential and infinite bus as reference points, the importance of infinity in power line analysis, the practical effects of short-circuits and open-circuits in power systems, and the continuity of state variables. By connecting theoretical and practical aspects, this article enhances the understanding of how infinity is utilized as a tool in electrical engineering, highlighting its importance in simplifying complex problems and advancing the design and analysis of power systems
Special issue on grounding systems
No full textThe articles in this special section focus on grounding systems for industrial, commercial, and residential installations
Currents Passing Through the Human Body: The Numerical Viewpoint
No full textIn the case of direct or indirect contact with electrically energized parts, an electric current circulates through the body. When the magnitude and duration of the current through the heart exceed the ventricular fibrillation thresholds, the cardiac muscle starts uncoordinated contractions, greatly jeopardizing the life of the subject. Technical standards on electrical installations describe the protective measures against direct and indirect contact necessary to minimize the probability of inception of ventricular fibrillation. Safety considerations are based on experiments made in the past on animals, but the extrapolation of results to human beings is complex and rather questionable. The purpose of this study is to analyze the body factors that affect the distribution of currents passing through the human body with virtual anatomical models. A set of 16 models of individuals is used to simulate different electric contacts. The use of virtual models of a diverse population (i.e., eight males and eight females, ten adults and six children) provides a statistical support to the results. The obtained heart-current factors, are compared with values present in the literature. This paper provides a novel viewpoint on the problem, and supports the ongoing research activity and efforts to improve the electrical safety of persons
Arc Welding Processes: An Electrical Safety Analysis
Full text linkManual metal arc welding can be a hazardous practice if proper precautions are not taken. The welding procedure uses an open electric arc between an electrode and the metals to be joined. Besides the obvious risks of burns and inflammation of the cornea, which are prevented by using proper personal protective equipment, the operator may also be subject to the risk of electric shock from the exposed parts of the welding circuit, both the electrode and the workpiece. In addition, the welding current, by straying from the intended path, can cause localized heating of parts, with the risks of triggering fires and/or explosive atmospheres. Because of the high current required by the arc welding equipment, operators are exposed also to strong electromagnetic fields. This paper seeks to clarify the aforementioned issues, especially in light of the fact that the risk associated with electric shocks may be unknown to welders and their supervisors
Energy Analysis in an Italian Opera House and Energy Savings Strategies
Full text linkThe refurbishment of historic buildings is a complex task in which the goal of obtaining a more energy-efficient building can conflict with the peculiar characteristics of the building’s environment and its intended use.
In this article, the authors address this problem for a very specific type of building: a historic opera house located in northern Italy. The results of energy consumption monitoring and spot measurements on selected
loads were used as a basis to propose energy-savings strategies. The objective of this article is to highlight the difficulties in refurbishing historic buildings, particularly regarding the building envelope, in lieu of proposing a new methodology for measurements or a new strategy for energy savings. It is documented that energy savings are obtainable with relatively small investments and low-impact construction work
Electrostatic hazards in power systems
No full textStatic electricity poses significant hazards in industrial and daily settings due to the potential for igniting flammable atmospheres, causing electric shocks, and damaging electronic devices. This paper examines the generation and accumulation mechanisms of static charge, including contact/separation of solids and liquid flow. It discusses hazards associated with static discharge in explosive atmospheres and provides a practical criterion based on the minimum ignition energy for determining maximum acceptable resistance-to-ground values. Effective mitigation strategies are presented, such as grounding and bonding of conductive parts, use of static dissipative floors (resistance <100 MΩ), and footwear (resistance <100 MΩ or lower). A holistic approach combining these measures with proper area classification and personnel training is emphasized for safe operations in hazardous industrial environments involving flammable substances. Calculations and examples illustrate the principles and highlight the importance of controlling static electricity accumulation
Equipotential bonding of photovoltaic systems
No full textThe modules of photovoltaic systems (PV), whether land-mounted or installed on building roofs, are secured by racks and mounting structures. These components are usually constructed from metal, prompting the question of whether electrical bonding for equipotential reasons is necessary. Solar trackers may be employed in photovoltaic systems, equipped with servo motors that orient the payload toward the sun to maximize energy production. The servo may fail and energize the mounting structures. This paper advocates for bonding decisions to be based on the specific characteristics of the PV system and to be made on a case-by-case basis. The paper discusses the distinctions between Class I and Class II PV equipment, highlighting the implications for grounding and bonding based on the type of insulation employed. Through a detailed exploration of the underlying principles, design considerations, and industry standards, this paper endeavors to equip readers with the knowledge and tools necessary to make informed grounding decisions for their specific PV installations. It aims to contribute to the ongoing efforts toward safer, more efficient, and sustainable energy generation by addressing these critical aspects of PV systems design
Analysis of causation of a flour dust explosion in industrial plant
No full textCommon solids (e.g. flour, sugar, etc.) can be suspended and transported in air via pneumatic conveying systems. Finely divided solid substances dispersed into a dust cloud (e.g. into a silo) can form a potential explosive atmosphere, if in the right concentration with the oxidizing agent (e.g. air). In addition, it is known that the pneumatic handling of substance, which allows its transport at a certain velocity, can generate static charges; thus, a possible competent ignition source may be also created. In this paper, the causation of an actual dust explosion involving a flour silo being loaded from a tank truck through pneumatic conveying systems in an industrial plant is analyzed. All the mechanisms of static discharge applicable to the case in question are discussed, in light of both actual empirical data collected at the incident site, and theory. To fully explain the events that led to the explosion, plausible hypotheses, alternative to static discharge, were also evaluated
Electrical safety in arc welding processes
No full textManual metal arc welding can be a hazardous practice if proper precautions are not taken. The welding procedure uses an open electric arc between an electrode and the metals to be joined. Besides the obvious risks of burns and inflammation of the cornea, which are prevented by using proper personal protective equipment, the operator may also be subject to the risk of electric shock from the exposed parts of the welding circuit, both the electrode and the workpiece. In addition, the welding current, by straying from the intended path, can cause localized heating of parts, with the risks of triggering fires and/or explosive atmospheres. Because of the high current required by the arc welding equipment, operators are exposed also to strong electromagnetic fields. This paper seeks to clarify the aforementioned issues, especially in light of the fact that the risk associated with electric shocks may be unknown to welders and their supervisors
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