Abstract
Содержание
Introduction
In accordance with GOST 12.1.009-76, the term electrical safety is understood as a system of organizational and technical measures and means to protect people from the harmful and dangerous effects of electric current, electric arc, electromagnetic field and static electricity. Theoretical justification and development of such a system and its individual components is the most important part of the work in the design of objects in any sector of the economy. Not accidentally there are many sections of electrical safety – in manufacturing, in agriculture, in mining, portable plants, buildings and constructions etc. But all these sections are based on the General requirements, the basics of electrical safety.
Electrical safety requirements are regulated by different Rules. Russia's first Rules and regulations for electrical devices heavy current created in 1912 by a Commission formed by the third electrical Congress in 1903, currently the consideration of the electrical conditions at the design stage reglamentary Rules of device of electrical installation PUE–98, and in the period of operation the Rules of operation of electrical installations peep–92 (more specific Rules of safety at operation of electroinstallations of PTB edition 1975 practically lost force in connection with the development of a new, but not yet approved version).
The effect of electric current on the human body
Electric current, passing through living tissues, has thermal, chemical, biological effects and secondary injuries. This leads to various disorders in the body, causing both local damage to tissues and organs, and General damage to the body.
Following electrical injuries: electrical burns, electric signs, metallization skin electronically and mechanical damage.
Electric shock-a defeat of the internal organs: the excitation of living tissues of the body flowing through the electric current, accompanied by involuntary convulsive muscle contraction. The degree of negative impact on the body of these phenomena may be different. In the worst case, an electric shock leads to a violation and even a complete cessation of the vital organs– lungs and heart, i.e., to the death of the body. At the same time, a person may not have external local injuries.
Causes of death due to electric shock may be the termination of the heart, cessation of breathing, and electric shock.
Termination of the heart, as a consequence of the impact of current on the heart muscle, the most dangerous. Cessation of breathing can be caused by direct or reflex action of current on the chest muscles involved in the breathing process. Electric shock-a kind of heavy neuro-reflex reaction of the body to severe irritation by electric current, accompanied by deep disorders of blood circulation, breathing, metabolism, etc.
Small currents cause only discomfort. With currents greater than 10-15 mA, a person is unable to free themselves from the current-carrying parts and the current becomes long-term (non-current). Prolonged exposure to currents of magnitude of a few tens of milliamps and a duration of 15 – 20 seconds may occur the respiratory paralysis and death. Currents of 50-80 mA lead to cardiac fibrillation, which consists in a disorderly reduction and relaxation of the muscle fibers of the heart, as a result of which the blood circulation stops and the heart stops.
Burns occur due to the thermal effect of the current passing through the human body, or from touching heavily heated parts of electrical equipment, as well as from the action of an electric arc. The most severe burns occur from the action of an electric arc in 35 – 220 kV networks and in 6 – 10 kV networks with a large network capacity. In these networks, burns are the main and most severe types of injury. In networks up to 1000 V burns by an electric arc are also possible (at shutdown of a chain open switches in the presence of the big inductive loading).
Electrical signs are skin lesions in the places of contact with electrodes of circular or elliptical shape, gray or white-yellow color with sharply defined faces (D = 5 – 10 mm) [1]. They are caused by mechanical and chemical actions of the current. Sometimes they do not appear immediately after the passage of electric current. Signs are painless, around them there is no inflammation. At the site of the lesion appears swelling. Small signs heal well, with large sizes of signs often occurs necrosis of the body (more often than hands).
Conclusion
If at the design stage of the facility documentation is agreed with the Supervisory authorities, requiring strict compliance with the Rules, during the period of operation, much depends directly on the specific persons organizing and performing the work. And here, for various reasons, they often neglect the requirements of safety Rules.
Modern man, surrounded by technology, frightening posters can not stop. Only one way to prevent electrical injuries can be effective-to develop a conscious attitude to electrical safety issues based on an understanding of all aspects of electric shock.
References
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