Research on method for detection of shunt state of track circuits

As track circuit is one of the means of train track occupation detection, the judgement of the shunt state of track circuit is crucial for train operation safety. In some sections where rust or dirt occurs on the rail surface, the shunt malfunction of track circuit caused by high shunt resistance is a major cause that affects shunt state reliability detection. In this paper, based on transmission line theory, a precise time-integration method was used to analyze the current response at the receiving end during the shunting of track circuit. A method was proposed to detect the shunt state of track circuit by making use of the mutation characteristics of the current signal at the receiving end. The influence of the variations of ballast resistance and power supply voltage on the current at the receiving end was investigated. Simulation analysis was conducted on the current response at the receiving end when the shunt resistance was too high. The results showed that a transient mutation of current signal occurred when the train entering or departing a track section, which can be used to determine the shunt state of track circuit and to effectively eliminate the shunt malfunction caused by high shunt resistance. © 2017, Editorial Office of Journal of the China Railway Society. All right reserved.