Browsing by Author "Al Said Ahmad, Mohammad Ahmad Diab"

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    Development of a Method of Calculating the Temperature of a Survey Assembly When Preparing a Train Dispatch
    (Львовский политехнический национальный университет, Львів, 2020) Ustymenko, Dmytro V.; Kuznetsov, Vitaliy; Marenych, Oksana L.; Kovzel, Maksim; Mukha, Andrii M.; Sinkevych, Oleksiy; Tryputen, Mykola; Al Said Ahmad, Mohammad Ahmad Diab
    ENG: The features of the thermal state of the current collection unit «contact wire – contact insert of the current collector» in the conditions of preparation of electric rolling stock for the journey are considered. As part of the study, a methodology has been developed for estimating the heating temperature of the power sliding contact zone in the conditions of train preparation for journey. Application of the method will help to reduce the number of «burnouts» of the contact wire due to the exact selection of the heating/cooling time of the train for a certain heating/conditioning current when preparing the electric rolling stock for the journey. It was established that the cause of the «burns» of the contact wire in the parking lots when preparing the train dispatch is the excess of the permissible temperature of the power sliding contact as a result of the prolonged action of the heating/conditioning current. The standard approach for determining the duration of heating is based on the average values of the loads on the system and therefore does not take into account some factors, for example, the state of the contact wire, the state of the contact insert of the current collector, the number of cars in the train, and so on. The proposed technique is based on the classical theory of electrical contact and the theory of heating a homogeneous body, which makes it possible to accurately assess the thermal state of the power sliding contact and convenient enough for use in operating conditions. The results of the work are of practical value, since the technology of preparing a train for dispatch can be supplemented by calculating the contact temperature «contact wire element – contact insert element» in accordance with the proposed methodology. This will allow for a specific train in specific conditions to apply a set of measures to prevent «burnout» of the contact wire in the event of a possible temperature exceeding the permissible value.
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    The use of Innovative Contact Strip for Pantographs of Electric Rolling Stock. Experience in Operational and Bench Tests
    (De Gruyter Open Ltd, Germany, 2021) Mukha, Andrii M.; Ustymenko, Dmytro; Al Said Ahmad, Mohammad Ahmad Diab; Kuznetsov, Valeriy; Skrzyniarz, Marek; Szulc, Waldemar
    ENG: Modern high-tech composite materials are widely used in various sectors of the economy, in particular, in railway transport. Among the areas of application of such innovative materials, the manufacturing of contact strips for pantographs of electric rolling stock should be mentioned. Innovation is primarily understood as the self-lubricating property of the working surface of the linings. The linings made of such materials differ from the traditional graphite (coal) ones by the increased content of metal additives, in particular copper, which limits the possibility of their use on electric rolling stock in the countries of the European Union. Regulatory restrictions on the content of copper (35% and 40%) are associated with possible damage to the contact wire, in the case of using overlays with a content of copper (metals) greater than these restrictions. On the railways of Ukraine (countries of the former USSR), there are also restrictions on the use of linings of different types according to the degree of wear of the contact wire, no more than 40 microns is allowed per 10 thousand passes of the locomotive pantograph along the contact wire. These standards are verified during operational and bench tests. The aim of the article is to present the types of tests and compare the obtained values with similar indicators in the case of using a traditional contact strip for pantographs of electric rolling stock. The results obtained confirm the possibility of using innovative linings on iron networks, since the wear of the contact wire during testing is much lower than that of the normative and knife than for traditional types of linings. In addition, during a set of tests, the fact of improving the quality of the working surface of the contact wire was established, which positively affects the extension of the service life of the contact wire.