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The action of electric current

  • The action of atmospheric electricity
  • Electric current unlike other traumatic factors causing damage to person by direct contact and may act in man, and indirectly, through the items in the distance, through the arc contact and step voltage. When forensic often encountered with electric shock on manufacture and in a life, much less often - with the action of atmospheric electricity (lightning). The action of electric current on the body is manifested in the electrical, thermal and mechanical effects and often leads to the development of extreme States, accompanied by acute disorders of cardiac activity (ventricular fibrillation of the heart and respiration, as well as to the emergence of shock reactions. Electric shock constitute 1-2,5% from all types of injuries, but the number of deaths and disability occupy one of the first places.
    The action of electric current in the manufacturing and in the home can cause serious and even lethal injury from contact with faulty appliances (table lamps, kettles, irons and others), included in the network with voltage of 127 or 200 C. In industry uses three-phase current with voltage of 380 V and frequency 50 Hz. This voltage is often heavy electrical trauma. There are direct and alternating current. DC and AC, equivalent in its effect on the body, respectively 120 and 42 C. DC less dangerous than the variable, only to a voltage of 500 Century At a voltage of 500 In danger of both types of current equal footing, and with voltages of more than 500 In a dangerous direct current. In practice defeat DC are rare. Severity of injury from electric current depends mainly on its physical parameters, but often are important circumstances in which acts current state of the body. The greatest danger exists under the influence of an alternating current with frequency 40 - 60 Hz.
    With increasing frequency electric oscillations of a threat of injury is reduced and when the currents of high frequency (more than 10 000 and up to 1000 000 Hz and even at high voltage (1500 V), and a large force (2-3 A) not observed the damaging effects on the body. This is based on wide application of high-frequency currents in medical practice for physiotherapy.
    Depending on the magnitude of the voltage is primary defeat of respiratory or circulatory. International norm safe voltage, the so-called reduced voltage is the potential difference in the 24th Century deaths possible already at a voltage of 40 C. the Currents of high voltage over 3000, less dangerous and rarely lead to death. This is because at high voltages between the body and the electrode there is the effect of electric arc flash and a large part of the electrical energy is converted into heat causing local lesions in the form of burns. The most frequent deaths under the action of the current with voltage from 100 to 1500 C.
    Important in the development of electric shock has a current value; the effect of current power 100 mA in overwhelming majority of cases is fatal.
    The biological effect of the current depends on the time during which the body is exposed current certain intensity, which is an important factor for the occurrence of ventricular fibrillation of the heart. Prolonged contact with the electrical conductors at current strength of 0.25-80 mA (minimum "netpurchase" current) can lead to death, causing convulsions respiratory muscles can result - acute asphyxia.
    Distribution of the electric current on the body is possible when the conditions for the input and output current. This happens when people at a time in contact with the two electrodes - two-polar enable or contact with one of the electrodes, and any part of his body grounded - single pole switching. Inclusion may be partial, when isolated from earth person regards one hand the opposite poles. Under these conditions, the current passes through included segment hands, that is usually not harmful. At a high voltage electric current can affect a person without touching the guide - at a distance, through the arc contact arising from dangerous approaching it. This ionization of air creates a contact person with electrical installations or wires. Danger of defeat at the distance increases significantly in wet weather due to the high conductivity of the air. At ultrahigh voltage electrical arc can reach a length of 35 see