RAIL TRACK DISTRIBUTED TRANSMISSION-LINE IMPEDANCE AND ADMITTANCE - THEORETICAL MODELING AND EXPERIMENTAL RESULTS

Frequency-dependent distributed transmission line self and mutual impe dances and admittances for a single-track, power-rail electrified rail way are obtained by experiment and modeling. Impedance results obtaine d by numerical calculation from an electromagnetic minimum energy fiel d solution using the finite-element method are compared with analytic impedance models based on the Carson-Pollaczek equations for a stratif ied, weakly conducting ground and with practical experimental measurem ents made on a short length of rail track. The running rail self condu ctances and the power rail to running rail mutual capacitances are als o evaluated by the finite element method and compared with experimenta l measurements. A physical interpretation of the results is given in t erms of conductive and induced ground currents caused by finite ground conductivity and relative permittivity.