Fail Safe Operation of Audio Frequency Track Circuits for Railway Signalling
01 Dec 2009-pp 1-5
TL;DR: In this article, a three-wire model of the track with PSpice as a simulation tool is used for analysis and the reduction in margin due to structure and cross bonds is also established.
Abstract: 4 prgoundan@cewit.org.in Abstract— An Audio Frequency Track Circuit (AFTC), a recent addition to railway signalling, confirms the absence of a train in a section of track. While the basic concept is established, several issues relating to proper operation of the AFTC need theoretical study. Installation practices like structure bonds and cross bonds, could lead to failure of AFTC operation, especially in the presence of breaks. An analysis is carried out, to study these influences on AFTC performance. Conjectured fault scenarios are identified which could lead to failure of the system, on the side of safety or otherwise. A three-wire model of the track with PSpice as a simulation tool is used for analysis and the reduction in margin due to structure and cross bonds is also established.
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04 Apr 2015
TL;DR: A new and innovative medium for railways that is Wireless Sensor Network (WSN) based Railway Signalling System is described and it is concluded that Introduction of WSN in Railways will not only achieve economy but will also improve the level of safety and efficiency of train operations.
Abstract: In the Railway System, Railway Signalling System is the vital control equipment responsible for the safe operation of trains In Railways, the system of communication from railway stations and running trains is by the means of signals through wired medium Once the train leaves station, there is no communication between the running train and the station or controller Hence, in case of failures or in emergencies in between stations, immediate information cannot be given and a particular problem will escalate with valuable time lost Because of this problem only a single train can run in between two nearest stations Now a days, Railway all over the world is using Optical Fiber cable for communication between stations and to send signals to trains The usage of optical fibre cables does not lend itself for providing trackside communication as in the case of copper cable Hence, another transmission medium is necessary for communication outside the station limits with drivers, guards, maintenance gangs, gateman etc Obviously the medium of choice for such communication is wireless With increasing speed and train density, adoption of train control methods such as Automatic warning system, (AWS) or, Automatic train stop (ATS), or Positive train separation (PTS) is a must Even though, these methods traditionally pick up their signals from track based beacons, Wireless Sensor Network based systems will suit the Railways much more In this paper, we described a new and innovative medium for railways that is Wireless Sensor Network (WSN) based Railway Signalling System and conclude that Introduction of WSN in Railways will not only achieve economy but will also improve the level of safety and efficiency of train operations
15 citations
07 Oct 2010
TL;DR: This algorithm can find the occupied track circuit in a route of any complexity and reduce the accumulated error by using the changing reference origin and clearing the train mileage, thus solving the difference between the real and simulated track circuit.
Abstract: In the simulation platform of high-speed train control system, it is necessary to simulate the track circuit occupation in order to provide basic conditions for other simulated equipment to calculate movement authority or generate track circuit code. A problem with the simulation of track circuit is that there may be more than one track circuit sections corresponding to one kilometer post. To solve this problem, this paper proposes an algorithm to precisely identify the occupied track circuit sections. In this algorithm, by using the signal machine as a reference origin, in combination with the the route information received from the simulated computer based interlocking equipment, train mileage is increased or decreased based on train running direction to find the occupied track circuit sections. The reference origin is always changing and the occupied track circuits inside or outside the station are identified by a unified “route”. This algorithm can find the occupied track circuit in a route of any complexity and reduce the accumulated error by using the changing reference origin and clearing the train mileage, thus solving the difference between the real and simulated track circuit. This algorithm reduces the complexity of simulating the occupation state of track circuit and lays a foundation for the construction of high-speed train control system simulation platform.
Cites background from "Fail Safe Operation of Audio Freque..."
...ALGORITHM ANALYSIS According to the railway fail-safe principle, real track circuit which is the safety-related equipment must be turned to the security side if it is failed [7]....
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References
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TL;DR: A comprehensive analysis of published experimental data and formulae for the determination of the electrical parameters of railway traction lines is performed in this paper, where several results from different authors are presented with particular attention to different assumptions and environmental conditions.
Abstract: A comprehensive analysis of published experimental data and formulae for the determination of the electrical parameters of railway traction lines is performed. Several results from different authors are presented with particular attention to different assumptions and environmental conditions. Additional measurements were performed over the 5 Hz-200 kHz frequency range on a line section purposely prepared at La Spezia Railway Station (Italian State Railways). Theoretical formulae are considered and their validity is checked against experimental data. There is general accordance within common variations of the most critical parameters; calculations and measurements agree over the entire frequency range and are very accurate in the frequency range 50 Hz-50 kHz, where significant conducted disturbance lies.
89 citations
01 Nov 1993
TL;DR: In this paper, the authors present a detailed analysis of appropriate electrical impedance models for steel railway rails suitable for power supply circuit transient calculations, which can be used to predict remote short-circuit-fault substation current profiles.
Abstract: The authors present a detailed analysis of appropriate electrical impedance models for steel railway rails suitable for power supply circuit transient calculations. They extend existing models to fully describe the skin effect, so that power circuit transient behaviour can be taken into account with little error in prediction of response. Practical measurements of rail impedance are compared with calculated values of circuit impedance and demonstrate an accuracy of within 9% for resistance and 18% for inductance. An associated paper (see ibid., vol.139, no.4, p.289-94, 1992) shows how this model can be used to predict remote short-circuit-fault substation current profiles.<
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45 citations
"Fail Safe Operation of Audio Freque..." refers methods in this paper
...All rail parameters obtained from experimental studies [1,2] and the S-bond parameters, are given in the Appendix....
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01 Nov 1999
TL;DR: In this article, an electromagnetic field model for identification of rail track equivalent multiconductor transmission line distributed self and mutual series impedances is formulated, and used to illustrate the parametric behaviour of single track impedance with reference to current, frequency, track material properties and ground conductivity.
Abstract: An electromagnetic field model for identification of rail track equivalent multiconductor transmission line distributed self and mutual series impedances is formulated, and used to illustrate the parametric behaviour of single track impedance with reference to current, frequency, track material properties and ground conductivity. Verification is demonstrated by theoretical analysis and comparison with published experimental data. The skin effect in both rails and earth is a critical phenomenon.
38 citations
25 Apr 1989
TL;DR: In this article, the effect of ground admittance and leakage conditions from both the traction and signaling viewpoints was examined, and capping compensation was evaluated as a means of improving the shunting sensitivity of track circuits with high ballast conductivity.
Abstract: A railway track acts as a pair of leaky ground-return conductors for propulsion current in the immediate vicinity of trains and as an imperfectly insulated conductor pair for double-rail track circuits. The authors consider the effect of ground admittance and leakage conditions from both the traction and signaling viewpoints. Problems concerning rail voltage safety level, earth leakage currents, and rail current distribution are examined. Capacitive compensation is evaluated as a means of improving the shunting sensitivity of track circuits with high ballast conductivity. >
24 citations
"Fail Safe Operation of Audio Freque..." refers background in this paper
...With masts connected to return rails, the receiver profile shows a significant increase, and the graph changes to a decreasing curve, above the previous curve [9]....
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TL;DR: In this paper, the application of SPICE to a rail traction network for the simulation of electromagnetic noise emissions and cab signal interference in a DC-fed rail rapid transit system is described.
Abstract: The application of SPICE to a rail traction network for the simulation of electromagnetic noise emissions and cab signal interference in a DC-fed rail rapid transit system is described. The predictions are validated by a laboratory experiment in which real-time signals are generated by computer using a programmable read-only memory (PROM) lookup table. The simulator can be used to study interference in rail rapid transit systems at low and audio frequencies produced by the combined effects of conduction, magnetic induction, and electric induction. Its use permits the influence of such variables as train position, power demand, and traction duty cycle on interference in cab signaling, track circuit, and other critical noise receivers to be determined. The effect of varying simulation parameters-for example, track impedance-can also be evaluated and parameters strongly influencing the degree of interference identified. The method can also be used to evaluate interference characteristics of new propulsion drives. >
13 citations