Common sense of electrical safety - part one

- Nov 07, 2017 -

Electrical safety is the application of science in the field of electrical safety, aiming at safety, and this science is associated with electricity, not just with electricity or electrical appliances.Therefore, electrical safety and electrical safety are not equal to the electrical Safety, but both are included in the electrical safety.Electronic safety, although involving many other sciences, but its main line is always around the electricity.The basic theory is electromagnetic theory.With the development of science and technology, electricity has become the industry and agriculture Production and people's lives, one of the important energy sources, the application of electrical equipment is also increasingly widespread, people have the opportunity to access electrical equipment increases. Without knowledge of safe electricity use, electric shocks, fires, explosions and other electrical accidents can easily occur, affecting production and endangering lives. Therefore, it is very necessary to study and discuss the law and prevention measures of electric shock accident.


I. Electrical accident classification


  From the energy point of view, the accident is caused by the failure of energy transfer from the external energy to the human body or the system, and energy is the basic factor causing the accident. Therefore, the electrical accidents are divided into five categories.


  1. Electric shock accidents and their types and laws


    The human body is a conductor, when the human body contacts with two different potentials, the current will be formed in the human body due to the effect of the potential difference. This phenomenon is electric shock. There are two types of current injuries to the human body: electric shocks and electric injuries. Electric shock is the current through the human body, affecting the respiratory, cardiac and nervous system, causing the body's internal tissue damage, resulting in death. Electric injuries are mainly localized injuries to the outside of the human body, including electric arc burns and molten metal infiltration into the skin. These two types of injuries may also occur in an accident at the same time, especially in the case of high-voltage electric shock accidents, most of which are electric shock accidents. The severity of electric shock damage is related to the amount of current passing through the human body, the duration of current passing through the human body, the way current passes through the human body, the frequency of the current, and the health of the human body.


Electric shock: Electric shock is the most dangerous electric shock accident. Most electric shock deaths are caused by electric shock. When people directly contact the charged body, current through the human body, so that the muscles numb, twitch, if not immediately from the power supply, will cause damage to the human nerve center, causing breathing difficulties, heart numbness, resulting in death.


Electric injury: Electric injury is the current of heat, chemical effects or mechanical effects on the human body caused damage. Electric injury more common in the external surface of the human body, leaving scratches on the human body surface. One of the most common arc burns, but also the most serious, can cause disability or fatal. In addition there are electric imprint, scald, skin metallization and so on.

 The majority of electric shock accidents are caused by people directly touching the charged body or equipment exposed to leakage due to insulation damage. They may also cause electric shock by standing around the ground fault point. Electric shock can be divided into the following categories:


A, people directly contact with charged body electric shock accident


     In accordance with the way the body touches the charged body and the current through the human body, such accidents can be divided into single-phase and two-phase electric shock. Single-phase electric shock refers to the human body on the ground or other grounded conductor, a part of the human body touches the one-phase charged body and the accident occurred. Two-phase electric shock refers to the two parts of the body at the same time touching the two charged bodies and the accident occurred, the greater the risk. Such accidents account for about 40% of all electric shock accidents.


B, electrical insulation accident damage electrical equipment contact accident


    Under normal circumstances, the electrical equipment of the metal shell is not charged, when the insulation damage and leakage, touch these housings, there will be an electric shock, the case of electric shock and contact charged body the same. Such accidents accounted for more than 50% of all electric shock accidents.


C, step voltage electric shock accident


    When the charged body grounded current into the ground, the current in the ground around the point of voltage drop, people appear in the ground around the feet between the voltage drop, resulting in step voltage electric shock.


Electric shock law:


    Mortality rates are high because of the sudden occurrence of an electric shock and serious consequences in a relatively short period of time. According to the statistical analysis of electric shock accidents, the law can be summarized as follows.


   A, with obvious seasonal. June to September each year is a frequent occurrence of electric shock. This is due to rainy and humid conditions during this period. Insulation performance of electrical equipment is reduced. At the same time, sweating increases the possibility of electric shock due to hot weather and sweaty clothes.


    B, low-voltage equipment, electric shock and more. This is due to the distribution of low-voltage power grids, low-voltage equipment and more simple, poor management, people have more opportunities for contact.


    C, young and non-electric shock and more accidents. These people lack of electrical safety knowledge, technology is not mature, prone to electric shock accident.


    D, portable and mobile devices, electric shock and more. This is because such equipment needs to be constantly moving, poor working conditions, and prone to failure.


    E, metallurgy, mining, construction, mechanical and electrical accidents and more. These industries work site more confusing, high temperature, humidity, mobile devices and more temporary lines and more difficult to manage.

2. Electromagnetic field accident


   Electromagnetic field injury is caused by the (electromagnetic wave) energy caused by the human body in the high-frequency electromagnetic field, the absorption of radiation energy will be different degrees of damage.Electromagnetic radiation on the human body mainly in its adverse effects on the human nervous system, its The main symptoms are neurasthenia, manifested as dizziness, listlessness, insomnia, fatigue, and memory loss and depression, and sometimes headache swollen, limbs, pain, loss of appetite, hair loss, sweating, weight Decline and so on. People often watch television or computer screen continuously for a long time, especially after people's eyes and ear fatigue, when watching at a closer distance in order to see clearly, some of the above feelings or symptoms often occur in the next day or period . Foreign medical research shows that "the use of computer terminals more than 20 hours a week, women have a higher probability of miscarriage." Despite the natural fatigue of our bodies, the adverse effects of electromagnetic radiation can not be ignored. In the early studies of the United States and the former Soviet Union, the above symptoms were common in personnel working in connection with electromagnetic radiation such as television, radio, radar, navigation, microwave relay and communications, when there were very few household appliances in those days.

  In addition to electromagnetic radiation may hurt people, but also may be induced by induction and energy transfer caused by electrical ignition circuit and electrical ignition device malfunction, resulting in a catastrophic explosion.


3. Electrostatic accident


     Electrostatic charge is the charge distributed over the surface or volume of a dielectric and at a standstill on the surface of an insulated conductor. Electrostatic phenomena is a common phenomenon of charging, is also more common in industrial production. On the one hand, people use static electricity for certain production activities, such as electrostatic dust removal, painting, flocking, mineral processing and photocopying. On the other hand, it should also prevent static electricity from causing harm to the production. For example, in the production of chemical, petroleum, textile, papermaking, printing and electronics industries, the solid insulating materials for transmission or separation, the powdery materials for conveying or stirring, Insulating liquid in the scour, high-speed injection of steam or gas will produce and accumulate dangerous static electricity. Although the static electricity is not large, but the voltage is high, prone to spark discharge, causing fire, explosion or electric shock. In order to prevent electrostatic hazards, chemical companies must do a good job in electrostatic safety, safety education and training so that workers understand the principles of static electricity and electrostatic hazards, to master the measures to prevent static electricity hazards.

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