3. Train line fault locator to be used with automatic electromagnetic air brake systems for freight trains

• An algorithm was built to locate a fault part in freight train line used for energizing solenoid valves for brake systems, which was then applied to build a device to detect the place of breakage.
• Tests on actual freight consists demonstrated that this system was capable of locating a failure in approximately 30 seconds.

One of the inspections performed after making up a freight train consist includes verifying the state of the train line used for applying automatic electromagnetic air brakes. If a disconnection is detected, it takes several hours to locate the breakage point.
This motivated research into devising an algorithm which made it possible to check for the presence of break in the line from one end of the train and developing a device for locating the failure if one was identified (Fig 1).

To produce the algorithm, firstly a network analysis model was built to reproduce the electric resistance between the cables and solenoid valves which represent the state of the train line used with an automatic electromagnetic air brake system. Based on the latter, approximately 200 closed loop equations were solved to yield a theoretical value for the combined resistance as seen from one end of the train consist (Fig 2). Comparison of the theoretical and measured values provides an indication of the presence or absence of a fault. This operation is performed while taking into account the influence of outside air temperature on the resistance value. In mock-up tests using the new system on a freight train, train line faults were detected up to the 20th wagon. For the remaining wagons, the system can be set up from the opposite end of the train which means that the system would be able to locate faults on commercial freight trains which comprise a maximum of 26 wagons.

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  Fig. 1 Fault detection device


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  Fig. 2 Example of electric network model of freight train consist