Interference from Traction-Current Harmonics in Rails on Automatic Locomotive Signaling Systems and Track Circuits

Abstract: Results of research on the asymmetry dependences of the first and third harmonics of alternating traction current under the receiving locomotive coils of the automatic locomotive signaling systems ALSN and ALS-EN on the type of asymmetry of resistances of homogeneous rail lines within the rail circuit are presented. The change in the asymmetry of the traction current’s first harmonic along the length of the rail circuit in the absence of rolling stock on it is studied. It has been found that the difference in the numerical values in the asymmetry distributions of the first and third harmonics along the length of rail lines is relatively small; however, other things being equal, the interference level from the traction current at the frequency of third harmonic of the traction current under the ALS-EN coils is less than from the first harmonic current under the ALSN coils. The reason for this is that the third harmonic usually does not exceed 20% of the total traction current. If there is no rolling stock on the track circuit, the first harmonic asymmetry of the traction current can increase or decrease as the traction current flows from the beginning to the end of the track circuit, depending on the type of asymmetry of resistances of the rail lines; therefore, it is incorrect to draw any conclusions about the preferred location for the installation of signal receivers of the track circuits. © 2023, Allerton Press, Inc.