Mounting wires as a source of ignition in electrical cabinets

2021 ◽  
pp. 27-35
Author(s):  
Геннадий Васильевич Боков ◽  
Антон Александрович Назаров ◽  
Денис Геннадьевич Боков

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.

2012 ◽  
Vol 2 (2) ◽  
pp. 33 ◽  
Author(s):  
Wenbin Sun ◽  
Xiaoyan Sun ◽  
Dianbo Cao

Liposarcoma is one of the most common soft-tissue sarcomas and classified as five groups. Dedifferentiated liposarcoma includes multiple elements such as solid tissue, adipose tissue and calcified tissue, which is different from common liposarcoma in tissue constitue. Dedifferentiation to osteosarcoma is rarely described in the literature. We reported the radiological and pathological findings in a case of dedifferentiated liposarcoma with osteo-sarcomatous dedifferentiation in the retroperitoneum and discussed the characteristic features of this specific tumor. Complete surgical resection of the neoplasm is the only curative means, but establishing a prognosis remains a challenge for long-term evaluation.


Author(s):  
Evgeniya V. Listvina ◽  

The article deals with the problem of transformation of modern communication processes caused by the formation of a new digital society and its influence on all aspects of social and cultural life. Communication becomes diverse, rhizomatically branched, offering an interweaving of channels and means of communication, a multivariate effectiveness and a change in the actual communicants, communication actors. It is noted that long-term social ties cease to be dominant. A qualitatively new environment, called the media space, lays down a new format of communication. Information is perceived in increasingly shorter blocks. The essence and depth of communicative interaction is flattened. People are increasingly communicating taking into account specific brief cases or events, uniting for their implementation in rapidly disintegrating fragile social formations. Horizontal socio-cultural ties and social stigmergia are being strengthened. There is a playization, which is becoming one of the characteristic features of modern communication. There is a leveling of communications, interactions of different levels and different tasks. The author notes that such changes contribute to the disappearance of hierarchy, multi-level, highly contextual interaction from the space and at the same time strengthen the emotional component of communication. All this creates conditions for qualitative changes in the meanings and methods of social interaction.


2021 ◽  
pp. 118-123
Author(s):  
В.Н. Круглеевский ◽  
В.В. Вислогузов ◽  
A.A. Таранцев ◽  
С.Н. Турусов

В настоящей статье рассматриваются вопросы развития пожарных извещателей, контролирующих появление дыма, превышение заданного значения температуры и скорости ее роста, наличие угарного газа и использующих мультикритериальные алгоритмы для оценки обоснованности сигналов тревоги. Анализируются результаты проведенных отечественными организациями сравнительных испытаний мультикритериальных и традиционных «пороговых» пожарных извещателей и возможности их применения на судах в составе систем пожарной сигнализации. Определено, что при повторении одних и тех же модельных очагов пожаров зафиксированные значения контролируемых параметров отличались незначительно. При этом для каждого модельного очага можно было обнаружить свои характерные черты. Сделан вывод о том, что внедрение мультикритериальных алгоритмов обработки информации в судовые системы обнаружения пожаров не только сокращает время обнаружения пожара, но и позволяет расширить функциональные возможности системы. Используя мультикритериальные пожарные извещатели в системах пожарной сигнализации можно будет распознавать, что именно горит: дизельное топливо, ветошь, изоляция электрического кабеля или что-либо другое. Отмечается, что требования к судовым мультикритериальным системам сигнализации обнаружения пожара нашли свое отражение в Правилах классификации и постройки морских судов Российского морского регистра судоходства. This article discusses the development of fire detectors that control the appearance of smoke, the excess of a given temperature and the rate of its growth, the presence of carbon monoxide and use multicriteria algorithms to assess the validity of alarm signals. The results of comparative tests of multicriteria and traditional fire detectors conducted by domestic organizations and the possibility of their use on ships as part of fire alarm systems are analyzed. It was determined that when the same model fires were repeated, the recorded values of the controlled parameters differed slightly. At the same time, for each model focus, it was possible to detect its own characteristic features. It is concluded that the introduction of multicriteria algorithms for information processing in ship fire detection systems not only reduces the time of fire detection, but also allows you to expand the functionality of the system. Using multi-criteria fire detectors in fire alarm systems,it will be possible to recognize what exactly is burning: diesel fuel, rags, electrical cable insulation, or anything else. It is noted that the requirements for ship multicriteria fire detection alarm systems are reflected in the Rules for the Classification and Construction of Marine Vessels of the Russian Maritime Register of Shipping.


2020 ◽  
Vol 15 (3) ◽  
pp. 76-88
Author(s):  
I. S. Taubkin

The article addresses the issues of the particular terminology for fire forensic investigations. Definitions for the basic parameters of a fire hazardous area, determining its susceptibility to ignition, and their relationship to the impulses initiating such areas’ combustion are analyzed.Two main tasks of forensic fire examinations are reviewed: establishing the technical cause of a fire, its organizational cause, and consequences. The author gives definitions for these tasks and the term “ignition source”.The paper’s relevance stems from the need to prevent mistakes in terminology when conducting a forensic fire investigation. The article may be of use for practicing experts and specialists in fire forensics’ theory and practice.


2019 ◽  
Vol 36 (2) ◽  
pp. 29-35
Author(s):  
I. A. Boev ◽  
A. P. Godovalov ◽  
G. I. Shtraube ◽  
G. I. Antakov

Aim. To study the characteristic features of long-term facial phlegmon morbidity in Perm Krai with assessment of the efficiency of infusion therapy using indices of endogenous intoxication expression. Materials and methods. Manifestations of epidemic process of facial phlegmons were studied on the basis of a detailed retrospective analysis of sickness rate among the inhabitants of Perm Krai for the period of 2011–2016. In group 1, all patients besides standard therapy, underwent infusion therapy, and in group 2 – standard therapy alone. Prior to and after the therapy, peripheral blood cellular composition was assessed, and leukocytic indices of intoxication were calculated. Results. A long-term dynamics of facial phlegmon morbidity was established to show the irregularity of process expression according to years. Growth of the quantity of patients is provided by increase in the number of cases with complicated forms. Besides, males play a significant role in formation of sickness rate: the chances for the development of phlegmon among them are 1.49 times higher than in females. In the age structure of morbidity, prevail persons aged 21–30 and 31–50. A half of patients have endogenous intoxication. The course of infusion therapy essentially reduces the expression of endogenous intoxication. Conclusions. There is observed a tendency to growth of facial phlegmon morbidity that is probably connected with changes in etiological structure of pathogenic agents as well as with formation of pathosymbiosis of some opportunistic pathogenic microorganisms. As a rule, phlegmon is being developed against the background of endogenous intoxication, conditioned by both microbial metabolites and tissue destruction products. The efficiency of correction of endogenous intoxication using infusion therapy is shown.


2010 ◽  
Vol 19 (8) ◽  
pp. 1026 ◽  
Author(s):  
Christopher Carcaillet ◽  
Pierre J. H. Richard ◽  
Yves Bergeron ◽  
Bianca Fréchette ◽  
Adam A. Ali

The hypothesis that changes in fire frequency control the long-term dynamics of boreal forests is tested on the basis of paleodata. Sites with different wildfire histories at the regional scale should exhibit different vegetation trajectories. Mean fire intervals and vegetation reconstructions are based respectively on sedimentary charcoal and pollen from two small lakes, one in the Mixedwood boreal forests and the second in the Coniferous boreal forests. The pollen-inferred vegetation exhibits different trajectories of boreal forest dynamics after afforestation, whereas mean fire intervals have no significant or a delayed impact on the pollen data, either in terms of diversity or trajectories. These boreal forests appear resilient to changes in fire regimes, although subtle modifications can be highlighted. Vegetation compositions have converged during the last 1200 years with the decrease in mean fire intervals, owing to an increasing abundance of boreal species at the southern site (Mixedwood), whereas changes are less pronounced at the northern site (Coniferous). Although wildfire is a natural property of boreal ecosystems, this study does not support the hypothesis that changes in mean fire intervals are the key process controlling long-term vegetation transformation. Fluctuations in mean fire intervals alone do not explain the historical and current distribution of vegetation, but they may have accelerated the climatic process of borealisation, likely resulting from orbital forcing.


Micromachines ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 184 ◽  
Author(s):  
Woohyun Jung ◽  
Sunyoung Jung ◽  
Ockchul Kim ◽  
HyungDal Park ◽  
Wonsuk Choi ◽  
...  

Massive efforts to develop neural interfaces have been made for controlling prosthetic limbs according to the will of the patient, with the ultimate goal being long-term implantation. One of the major struggles is that the electrode’s performance degrades over time due to scar formation. Herein, we have developed peripheral nerve electrodes with a cone-shaped flexible artificial conduit capable of protecting wire electrodes from scar formation. The wire electrodes, which are composed of biocompatible alloy materials, were embedded in the conduit where the inside was filled with collagen to allow the damaged nerves to regenerate into the conduit and interface with the wire electrodes. After implanting the wire electrodes into the sciatic nerve of a rat, we successfully recorded the peripheral neural signals while providing mechanical stimulation. Remarkably, we observed the external stimuli-induced nerve signals at 19 weeks after implantation. This is possibly due to axon regeneration inside our platform. To verify the tissue response of our electrodes to the sciatic nerve, we performed immunohistochemistry (IHC) and observed axon regeneration without scar tissue forming inside the conduit. Thus, our strategy has proven that our neural interface can play a significant role in the long-term monitoring of the peripheral nerve signal.


2014 ◽  
Vol 778-780 ◽  
pp. 767-770 ◽  
Author(s):  
Norimasa Yamamoto ◽  
Satarou Yamaguchi ◽  
Tomohisa Kato

Recently, ingots of silicon carbide have been adapted to be sliced by the wire-cut electrical discharge machining. Fast slicing, and the reduction in the loss are important for slicing of the wafer. In this paper, characteristic features of the electric discharge machining in the ion-exchange water and the fluorine-based fluid were compared for these improvement. The discharge was caused by a pulse voltage applied to a ingot of silicon carbide and the wire in machining fluid, and the slicing was proceeded. As a result, improvement of surface roughness and kerf loss was confirmed, for the first time. In addition, the improving methods for fast slicing were considered.


Cephalalgia ◽  
2008 ◽  
Vol 28 (1_suppl) ◽  
pp. 28-31 ◽  
Author(s):  
LJ Stovner ◽  
D Obelieniene

Acute and chronic whiplash headache are new diagnostic entities in the ICHD-2 (5.3, 5.4). In a prospective cohort study, 210 rear-end collision victims were identified consecutively from police records and asked about head and neck pain in questionnaires after 2 weeks, 3 months and 1 year. The results were compared with those of matched controls who were also followed for 1 year. Of 210 accident victims, 75 developed headache within 7 days. Of these, 37 had also neck pain and complied with the criteria for acute whiplash headache. These 37 had the same headache diagnoses, headache features, accompanying symptoms and long-term prognosis as the 38 without initial neck pain who therefore did not comply with the acute whiplash headache diagnosis. Previous headache was a major risk factor for headache both in the acute and chronic stage. Compared with the non-traumatized controls, headache in the whiplash group had the same prevalence, the same diagnoses and characteristic features, and the same prognosis. Both acute and chronic whiplash headache lack specificity compared with the headache in a control group, and have the same long-term prognosis, indicating that such headaches are primary headaches, probably elicited by the stress of the situation.


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