Study on the rail-broken state of centre-fed boundless track circuits

Abstract

One of the difficult problems about track circuit analysis is to develop a mathematical model in the rail-broken state. When it comes to the centre-fed boundless track circuits, the influence of parameters of current sensors and equivalent impedance of receiving circuits on track circuit must be taken into account. Using transform in circuits, the equivalent circuits of receiving ends are deduced, and the equivalent circuit and two-port network model in the rail-broken state of track circuit have been established. According to the equivalent circuits, a mathematical model in the rail-broken state has been deduced and the formulae for calculating the parameters of transmission matrix, current of rails, induced voltages of the current sensors and transfer impedance at the receiving ends of track circuits are presented. From these formulae, it has been showed that the influence of the parameters of current sensors and the equivalent impedance of the receiving circuits on track circuits can be achieved by analyzing the influence of certain impedance on the transfer impedance. The results of an example act in accord with the relevant one of [2], which has confirmed the analysis methods and conclusion in the paper are credible and useful.