scholarly journals Identification and Localization of Track Circuit False Occupancy Failures Based on Frequency Domain Reflectometry

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7259
Author(s):  
Tiago A. Alvarenga ◽  
Augusto S. Cerqueira ◽  
Luciano M. A. Filho ◽  
Rafael A. Nobrega ◽  
Leonardo M. Honorio ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Fault Location ◽  
Short Circuit ◽  
Signal Amplitude ◽  
Railway Track ◽  
Economic Losses ◽  
Track Circuits ◽  
Frequency Domain Reflectometry ◽  
Track Circuit ◽  
Maintenance Process

Railway track circuit failures can cause significant train delays and economic losses. A crucial point of the railway operation system is the corrective maintenance process. During this operation, the railway lines have the circulation of trains interrupted in the respective sector, where traffic restoration occurs only after completing the maintenance process. Depending on the cause and length of the track circuit, identifying and solving the problem may take a long time. A tool that assists in track circuit fault detection during an inspection adds agility and efficiency in its restoration and cost reduction. This paper presents a new method, based on frequency domain reflectometry, to diagnose and locate false occupancy failures of track circuits. Initially, simulations are performed considering simplified track circuit approximations to demonstrate the operation of the proposed method, where the fault position is estimated by identifying the null points and through non-linear regression on signal amplitude response. A field test is then carried out in a track circuit approximately 1500 m long to validate the proposed method. The results show that the proposed method can identify and estimate the fault location due to a short circuit between rails with high accuracy.

Research of Aircraft Cable Fault Detecting Method Based on Hilbert Huang Transformation

2011 ◽  
Vol 214 ◽  
pp. 138-143
Author(s):  
Tao Jing ◽  
Lu Zhang ◽  
Xu Dong Shi ◽  
Li Wen Wang
Keyword(s):  
Frequency Domain ◽  
Short Circuit ◽  
Reference Signal ◽  
Open Circuit ◽  
Time Domain Reflectometry ◽  
Transform Method ◽  
Hilbert Huang Transform ◽  
Intermittent Faults ◽  
Time Frequency ◽  
Frequency Domain Reflectometry

Aircraft cable fault diagnosing is considered to be most important for engineering maintenance. Several methods for cables testing have been developed, such as TDR, FDR and TFDR. Time Domain Reflectometry (TDR) relays much on impedance changes on the fault position, which is hard to using in detecting high resistance defects, intermittent defects; Time Frequency Domain Reflectometry (TFDR) method is used to locate intermittent faults, continuous faults and cross-connection faults aircraft wire, however, the algorithm of TFDR is complex. To the "Hard Fault"(short circuit and open circuit), the Hilbert-Huang Transform method is used in determining the optimal bandwidth of the incident reference signal and analyzing the phase and amplitude difference of superimposed signal which from the incident signal and the reflected signal on defects. To the "Fray Fault", Time and Frequency Domain Reflectometry method can be used with the signal processing method with Hilbert-Huang Transform. The experimental results indicate that this method effectively detect all types of aircraft cable fault, particularly for short lengths of cable.

scholarly journals Transient analysis on track circuits in crack state

2018 ◽  
Vol 173 ◽  
pp. 02046
Author(s):  
Zhao Bin
Keyword(s):  
Frequency Domain ◽  
Normal State ◽  
Traveling Wave ◽  
Transient Analysis ◽  
Complex Frequency ◽  
Track Circuits ◽  
Zero Moment ◽  
Track Circuit ◽  
Electro Magnetic ◽  
The Time Domain

The transient transformation of track circuit between the normal state and crack state is analyzed. Firstly, the model of crack state of track circuit in the complex frequency domain is established. According to the boundary conditions of crack state of track circuit, the expression of current traveling wave in the receiving end is obtained in complex frequency domain. Based on it, the numerical solution in the time domain is got by FFT&IFFT conjunction with quotient-difference (Q-D) algorithm. Then, the steady state of circuit in normal state is taken as state of zero moment of track circuit, the transient process from normal state transform into crack state is solved. Thirdly, the Electro-Magnetic Transient Program (EMTP) model of crack operation is established to prove that the transient analysis result is correct. It provides a power theoretical basis to distinguish the operation state of track circuit by transient analysis.

scholarly journals Elektromagnetiese modelle vir elektriese spoorbaanstelsels

1997 ◽  
Vol 16 (2) ◽  
pp. 86-95
Author(s):  
B. M. Steyn ◽  
J. D. Van Wyk
Keyword(s):  
Performance Analysis ◽  
Transmission Line ◽  
Current Distribution ◽  
Electromagnetic Interference ◽  
Railway Track ◽  
Traction Current ◽  
Different Types ◽  
Track Circuits ◽  
Track Circuit ◽  
Electromagnetic Models

The use of electromagnetic models is very expedient when railway track circuits are designed or when their operation is being studied. These electromagnetic models include models for performance analysis of the different types of track circuits as well as models used to study the effect of electromagnetic interference. Before these models can produce useful results they all require accurate input parameters. These parameters include the transmission line parameters of the track and the traction current distribution along the length of the track. Models that have been developed for these parameters are presented in this paper, together with an overview of the available track circuit models.

Disc machine study of contact isolation during railway track sanding

2003 ◽  
Vol 217 (1) ◽  
pp. 11-24 ◽  
Author(s):  
R Lewis ◽  
R. S. Dwyer-Joyce ◽  
J Lewis
Keyword(s):  
Severe Case ◽  
Open Circuit ◽  
Electrical Circuit ◽  
Test Method ◽  
Railway Track ◽  
Electrical Isolation ◽  
Stage Of Development ◽  
Dry Contact ◽  
Track Circuits ◽  
Track Circuit

An experimental study has been carried out to investigate the effect of sanding on the electrical isolation of a wheel/rail contact. Sand is applied to the wheel/rail interface to increase adhesion in both braking and traction. Train detection, for signalling purposes, can be by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train ‘shorting out’ the track circuit. Sand in the wheel/rail interface means that contact between the wheelsets and the track may be compromised, inhibiting train identification. Tests were performed on a twin-disc machine where rail and wheel steel discs are loaded together and driven under controlled conditions of rolling and slip. Sand was fed into the disc contact through a standard compressed air sanding valve. The electrical circuit used was a simplified simulation of the TI21 track circuit. The application of sand with and without water to the discs was carried out under a range of mild and severe test conditions. The results indicated that a transition exists in the sand flowrate below which there is a measurable, but not severe, change in voltage, but above which the contact conductance decreases by an order of magnitude and the voltage tends towards its open-circuit value. The total isolation time also showed a similar transition. Contact resistance was modelled assuming full disc separation by a sand layer and partial disc contact with some sand present. Traction was monitored during the tests. A wet contact showed approximately half the traction of a dry contact. The addition of sand increased the traction to levels observed in a dry contact. Idealizations inherent in the test method mean that it represents a severe case. The disc geometry is smaller than a wheel/rail contact and both are in rotational motion. The sand nozzle was placed closer to the interface, leading to greater sand entrainment and low inductance. A fast data acquisition rate made the test circuit more sensitive to small fluctuations in isolation than an actual track circuit. Given these limitations, it is likely that the test method, at its present stage of development, should be used as a means to assess qualitatively the relative effects on electrical isolation of different contaminants.

Sign in / Sign up

Export Citation Format

Share Document