Response to Electrical Stimuli

ArticleinIEEE Industry Applications Magazine 15(3):22 - 30 · July 2009with2 Reads
DOI: 10.1109/MIAS.2009.932362 · Source: IEEE Xplore
Electrical safety is important in industrial work. This article provides considerable detail on how current can pass through different parts of the body and each parameter that can impede or limit the flow of current. Electric currents flowing through a human body can have varying effects, ranging from little or no perceptible effect, to shocking sensation, to possibility of electrocution, depending primarily on the magnitude and the duration of the current flow. The effect of current flow is a function of the applied voltage level, the duration of the exposure, and the resistances or impedances of the body and the other available current paths. A key consideration with energized objects is that, in order for the electric current to flow through the body, one body part must make contact with an energized object or conductor and another body part must make contact with the earth or an object or conductor that provides a path for the current to return to its source. This article supplies considerable detail on how currents can pass though different parts of the body and each parameter that can impede or limit that flow of current. The information presented indicates that the most likely scenarios for a dangerous condition would be that when a person comes in contact with an energized metallic object energized at 120 V and the person is barefoot and the ground is moist or wet as are the persons' hands or feet. Nearly, any other condition such as dry ground, rubber, or leather soled shoes; dry hands and so on have a lower probability of creating current flows that would be considered damaging or disruptive.
    • "Experiments proved a relationship between the tolerable body current I and the current duration t expressed by a constant value I 2 t; this relationship is based on the body mass of the injured. In [11] the response to electrical stimuli are analyzed in strict reference to existing literature and in light of the data presented in [5] by the International Electrotechnical Commission. A preliminary consideration is about the obvious difficulty at carrying out experiments with volunteers when the most dangerous effects of currents need to be studied; difficulties also arise when electrical accidents must be investigated. "
    [Show abstract] [Hide abstract] ABSTRACT: Contact with energized parts at different potentials may cause the circulation of body current and the possible inception of the ventricular fibrillation, which is generally considered the most life-threatening effect imposed on the cardiac muscle. The heart-current factors currently present in international standard have been determined owing to measurements on cadavers as well as experiments with volunteers. Due to the difficulties in experimental verifications, the authors propose the use of numerical techniques to investigate the behavior of the human body when it is subjected to electric fields, with the fundamental purpose of increasing the electrical safety of installations. This work is based on a mathematical representation of the human anatomy, which takes into account the boundaries of the internal organs. The simulations carried out and documented in this paper show results that do not entirely match the published IEC heart-current factors; most noticeably, for the pathways hands-feet, right hand-feet, and left hand-right foot, the heart-current factors seem to be overestimated by the IEC.
    Full-text · Article · Sep 2013
  • Article · Sep 2009
  • [Show abstract] [Hide abstract] ABSTRACT: The bonding of electrical equipment plays a crucial role in maintaining the same potential between conductive parts likely to be energized and conductive parts liable to introduce a “zero” potential into the premises. Voltage rises between such parts are unsafe, as they may induce harmful currents through the human body, the magnitude of which may vary depending on a number of factors. This paper seeks to clarify the bonding requirements in low-voltage electrical systems, by using the concepts of exposed conductive parts and extraneous conductive parts, present in the International Electrotechnical Commission standards, applied to a proposed electric shock model of the human being. With the purpose of reducing the consequences of electric contacts, the authors propose objective criteria to decide whether conductive “dead” objects and enclosures of electrical equipment must be bonded or not.
    Article · May 2011
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