Method for assessing the state and residual life of the insulation based on analysis of the time of discharge of the capacity of electric cables

As of today, the problem of the lack of non-destructive methods for assessing the state and determining the residual life of the insulation of electrical cables is relevant for cable lines in operation, and especially for lines that have exhausted their service life. The research presented in the framework of this article is aimed at creating a non-destructive technique for assessing the state and residual life of electrical cables insulation. The study was carried out using computer simulation methods and using the basic theoretical laws of physics and electrical engineering. A method for assessing the condition and residual life of electrical cable insulation has been developed, which is based on the analysis of the discharge time of the cable capacity. The applicability of the method is determined, instructions are given on its applicability and the analysis of the output data. The obtained results can be used by power grid companies and industrial enterprises to analyze the state of the insulation of electrical cables.

Design and Development of a Micro-LDH Apparatus to Determine Formability of Sheet Metal Under Hot Stamping Conditions Using Gleeble

In the last few years, demand for hot stamped components has increased in the automotive industry. Determination of formability under hot stamping is challenging due to elevated temperature, fast cooling and high punch velocity. Although there was various strive for formability determination but had limitations with experiments like non-uniform heating of specimen, non-uniform strain and temperature distribution. Therefore, in this work, an experimental apparatus was developed to determine formability at room temperature, high temperature, hot stamping conditions, and any complex process cycle involving heating and cooling. New specimen was designed to produce different strain paths, uniform and homogenous temperature distribution with the help of FEM software using thermomechanical and thermoelectrical simulation. A micro hemispherical dome based experimental apparatus was designed using Solidworks. The designed apparatus was used in conjunction with the thermo-mechanical simulator (Gleeble-3800). Thermomechanical analysis was done in PAM STAMP software to optimize specimen size and shape to get uniform strain distribution and different strain paths. A thermoelectric FEM model was developed using Abaqus 6.14 to optimize the temperature distribution in the specimen. The developed model enables choosing the appropriate polarity of the electrical cable connection to achieve uniform temperature distribution in the specimen. Strain path and temperature profiles for experiment and simulation were compared. Further, a forming limit curve was developed using the designed apparatus to verify the feasibility of the apparatus. For feasibility test of apparatus, hot stamping process was selected. This new design apparatus can be used for a range of temperatures up to 1000 °C, hot stamping conditions, and for different materials (aluminium, magnesium alloys, different grade of steel, etc.). It concludes that the connection of different polarities of electrical cable was critical for homogenous and uniform temperature distribution in specimens.

New functions of multicriteria ship fire alarm systems

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.