Arc process features at post fire expert examination of car fuse elements

The data given in the article indicate that vehicle fires belong to super severe accidents therefore the problem of improving the fire safety of vehicles is very relevant. In particular, Reuters reports that the German car concern Daimler has recalled 1 million new Mercedes-Benz models around the world in 2017 due to the risk of ignition caused by defective fuses. Daimler note in their report that in total 51 cases of fire have been recorded consequently car production and sale are suspended. These are the reasons why development of fire prevention actions for cars is of high importance. Fire investigation is one of the preventive actions. The article reports that the overwhelming number of firefighting experts’ findings concerning the technical routes of car fires is of a presumable (probabilistic) nature. This does not allow developing and implementing specific engineering solutions. This can be explained by many reasons including the lack of scientifically based methods. In detail, the problem of identifying the electric arc or thermal processes that cause destruction of a car fuse conductor or fuse strip has not been unequivocally solved despite the fact that attempts to solve this problem using instrumental control have been undertaken by criminologists since the fifties of the last century and there is a number of particular solutions. The article provides findings of the car fuse strip sample examination at the JSM-6390LV scanning electron microscope for 12 V electric circuit exposed to external high temperature and current overload. It also gives images of the strip fused surface for car fuses made of copper, zinc, aluminum, and those exposed to the overload current and high temperature. The typical diagnostic features in the form of wave-like inflows and micro-fusing have been found. They are used to identify the cause of fire damage (high temperature, current overload) of fuse strips in the 12 V electrical circuit. It has been found that the revealed features are stable and they are not subject to any changes in the natural storage conditions of a car damaged by thermal exposure. The data given in the article can be used by experts when examining fuse strips taken from the locations of vehicle fires, determining the nature of their damage and, ultimately, finding the cause of the car fire.

пожар, предохранитель, плавкая вставка, токовая перегрузка, медь, алюминий, цинк, растровая электронная микроскопия, диагностический признак, микрослед, пожарно-техническая экспертиза, пожар, предохранитель, плавкая вставка, токовая перегрузка, медь, алюминий, цинк, растровая электронная микроскопия, диагностический признак, микрослед, пожарно-техническая экспертиза, fire, fuse, fuse strip, current overload, copper, aluminum, zinc, scanning electron microscopy, diagnostic feature, ultratrace, fire investigation

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