Study On Voltage Measuring Device For Catenaries Without Ground Wire

With continually improved proportion of double-line electrified railway, induced voltage of blackout contact wire during overhaul of catenaries will increasingly grow, which will result in problems of "zone where no electricity checked" and "alarm for power failure" in traditional high-voltage electroscope, commonly used in verification of live part. Therefore, there may be major potential safety hazard in overhaul of catenaries arising from erroneous judgment accordingly incurred. Aiming at defect of traditional high-voltage electroscope, the quantitative measuring equipment for catenaries’voltage without ground wire, based on space electric field effect, is developed in this text. Its principle is placing a plane-parallel capacitor under the catenaries to form a space capacitive voltage divider with catenaries and the earth, conducting depression and rectifier filtering on secondary-side output voltage of voltage divider, which will be carried out with A/D switch by single chip microcomputer. Then the measuring result will be displayed on LCD screen. Finally, the quantitative measurement without ground connection is realized.Firstly, this text studies the measurement environment of voltage measuring equipment for catenaries, establishes mathematic model of power frequency electric field of catenaries and analyzes distribution characteristics of electric field and potential of electrified catenaries and blackout catenaries in double-track zone. Then it states basic principle of voltage measuring equipment and major factors that may affect equipment stability; acquires transfer function of voltage signals at different levels; and designs structure, signal processing circuit and program of measuring equipment. Finally, it conducts placement test and integral text on signal processing circuit in laboratory’ environment, as well as calibration and test on integral equipment in different places on voltage measuring site.Measuring equipment can realize quantitative measurement on voltage of catenaries without ground wire, which can effectively solve problems of erroneous judgment of traditional high-voltage electroscope and actually reflect running status of catenaries. With experimental test and site test, satisfies engineering surveying requirements on centenaries’voltage.