Thermal modes of operation of power-current contact of electric transport during conduct of bench tests

Purpose. Analysis of the results of bench tests of sliding electrical contacts of electric vehicles, in order to determine the thermal regime of the sliding contact. Methodology. The initial data were obtained during field experiments on a specialized stand in the laboratory, which were carried out to determine the wear of the contact wire inserts of different types for pantographs of electro-rolling stock of railways. To determine the contact wire temperature at the place of sliding contact, a non-destructive non-contact method of control using a thermal imager was used. Findings. During the experimental part of the research, the  thermal imaging photographs were obtained, they recorded the temperatures at the place of sliding contact between the insert of the pantograph of the electric rolling stock and the contact wire installed on the test disk. These temperature values were recorded with a certain time interval, which allowed to build the dependences of changes in thermal regime over time, to determine the heating time constant of the "insert-contact wire" of the test bench and to obtain the final temperature value at the end of tests. Accepting the insert sample in which the minimum temperature in the area of sliding contact is as a reference, it becomes possible by the value of the temperature of the contact wire in the area of sliding contact to predict the final test result of other types of pads. Originality. Indicators of temperature modes of sliding contact of electric vehicles during bench tests are obtained for the first time, the proposed relative temperature indicator allows to predict the results of bench tests of qualitative indicators of sliding contact of electric vehicles.. Practical value. Bench tests of inserts of current collectors of electric vehicles are a long procedure, the normative indicator of the number of passes of the current collector on the stand is equal to 500 thousand passes, which requires significant expenditure of time, energy, human resources and others. The indicators proposed according to the test results, namely the heating time constant and the relative temperature index, allow to carry out two-stage tests. At the first stage, with a duration of 10 thousand revolutions of the test bench disk, the proposed indicators are determined and compared with the corresponding reference, in case of their compliance it becomes possible to predict the final test result as successful (contact wire wear less than normal) or unsuccessful. In the latter case, the need for the second stage of testing up to 500 thousand revolutions is questionable, because the end result will be negative, and the significant resources will be involved in the test, and therefore these tests are impractical.