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Приведены результаты исследований монтажных проводов электрических шкафов на воспламеняемость под воздействием тока. Выделены три зоны сверхтока, имеющие отличительные особенности появления источника зажигания. Показано влияние изоляции провода на частоту появления воспламенения в местах присоединения его к элементу электрооборудования. Представлены данные о воспламеняемости поливинилхлоридной изоляции в диапазоне пожароопасных значений сверхтока. Предложено характеризовать электрический провод как потенциальный источник зажигания площадью, образованной зависимостью времени воспламенения изоляции в интервале возможных сверхтоков. Wires are widely used for internal installation of electrical cabinets. Number of fire cases caused by wires takes one of the first places in fire statistics. Application of wires in the cabinets has its own fire-prone aspects peculiarities as concerns initiation of electrical nature ignition source. It appears both at single wire laying and at laying in cords where wires touch each other also in connection points of electrical apparatuses and devices located in the cabinet. The article considers issues of ignition source appearance in wires taking into account specifics of their installation in electrical cabinets. Ignition source appearance in a single wire and in wires contacting each other has a difference. There are given experimental data on inflammation frequency of wire insulation material at single wire laying and also at higher resistance in electrical elements connection points. Zones that differ in characteristic features of wire as an ignition source are given in the range of possible overcurrents. Zone A is characterized by insulation ignition with low probability due to low current density that is not enough to heat the wire up to the critical temperature Т, at which thermal decomposition products of wire insulating polymeric cover ignite. Zone B is designated in the range of overcurrent ratio from 2,5 to 18 compared with the long term permissible current value, in which insulation inflammation is observed due to fast conductor heating taking into account the influence of connection points with devices and apparatuses where increased transient resistance is present. It is experimentally confirmed that with the increase in transient resistance at the point of conductor connection with electrical equipment elements, the inflammation frequency of wire insulation increases. At the same time, the overcurrent range where ignition source appears reduces. It is proposed to use the area limited by the dependence of the time before insulation inflammation from the minimum to the maximum current value at which ignition occurs as a characteristic of the wire as an ignition source.

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На основе анализа результатов многочисленных зарубежных и национальных исследований установлены виды аварийных режимов, вызывающих загорания литиевых аккумуляторных батарей, а также даны рекомендации по их превентивной защите. Рассмотрено такое явление, как тепловой разгон литиевого аккумулятора. Отмечается, что условием возникновения теплового самовоспламенения, т. е. перехода медленной реакции окисления в горение (при определенных условиях - во взрыв) является нагрев смеси до температуры, при которой скорость тепловыделения за счет реакции окисления превышает скорость теплоотвода из зоны горения. Описаны виды испытаний, связанных с явлением теплового разгона литиевых аккумуляторов, и способы предотвращения таких пожаров. It is difficult to imagine modern life, including the production activities of industrial enterprises, without the use of lithium batteries. They are everywhere: electronics, consumer electronics, cordless tools, electric vehicles, various types of forklifts and electric cars, and much more. In the energy sector, these are energy storage devices (wind, solar) and, of course, uninterruptible power supply devices, taking into account especially important consumers of the first category in terms of power supply reliability, including fire protection systems. But there is a very significant problem, which, to a certain extent, holds back the area expansion of lithium batteries application: the constant increase in the number of fires and even explosions. Data are given on the occurrence of numerous cases of their ignition in the United States, as well as cases of such fires in recent years in transport in the Russian Federation. Based on the analysis of foreign and domestic publications, there are considered the classification and operating principles of lithium batteries. Analytical issues of the phenomenon of thermal acceleration in lithium batteries are discussed. A diagram of the battery pack design with various options for battery modules and cell configurations is provided. A separate section of the article is devoted to experimental studies related to the testing of lithium batteries for fire hazard, in accordance with the requirements of national standards. Test methods for overcharging, mechanical damage, thermal and other types of tests are briefly outlined. In the final part of the article there are given ways to prevent fires. The first category contains preventive measures, at which flame retardants are added to polymeric materials for thermal stability of the battery. The second category includes design measures that increase the fault tolerance of lithium batteries and reduce damage when thermal acceleration occurs. There is an installation of shut-off separators, safety valves that respond to excess pressure or temperature, ventilation of the cell, etc.

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