SYSTEMS AND METHODS FOR MONITORING A RAILROAD WAYSIDE ELECTRIC FENCE

Abstract

 A method for monitoring a status of an electric fence (150), the method comprising: providing a current to a circuit of the electric fence (150), wherein the circuit of the electric fence (150) includes a test switch (141), receiving a first output from a monitoring circuit (114) coupled with the circuit of the electric fence (150), wherein the first output is received when the test switch (141) is closed, opening the test switch (141) and receiving a second output from the monitoring circuit (114) when the test switch (141) is open, comparing the first output and the second output, and assessing the status of the electric fence (150) based on the comparison.

Description

Technical Field

[0001] The present disclosure relates generally to systems and methods for monitoring and diagnosing an electric fence protecting railroads.

Background

[0002] Railroads are prone to intrusion by other vehicles. If a vehicle intrudes a driverless railroad, the trains on the railroad may not be stopped promptly to avoid potential accidents. One protection approach is a perimetric wire (e.g., electric fence) installed on the railroad wayside that makes a current loop, such that when the fence is broken (e.g., by a vehicle intruding the railroad), a monitoring circuit may be activated to generate a protection signal. However, problems arise when the wires of the electric fence are long and have wire-to-wire and/or wire-to-ground short circuits at some points. When these faults are not detected, no protection signal will be generated even if the fence is broken. Thus, there is a need for systems and methods for monitoring and detecting faults in such electric fences.

[0003] U.S. Patent No. 5,771, 147 ('147 patent) discloses methods and systems for determining the quality of the connection between an electric fence to ground. The methods and systems in the ' 147 patent measures a voltage between a portion of the electric fence and a ground potential. However, the ' 147 patent fails to disclose any method or system for monitoring the status of an electric fence. The systems and methods of the present disclosure may solve one or more of the problems set forth above and/or other problems in the art. The scope of the current disclosure, however, is defined by the attached claims, and not by the ability to solve any specific problem.

Summary of the Disclosure

[0004] In one aspect, a method for monitoring a status of an electric fence includes: providing a current to a circuit of the electric fence, wherein the circuit of the electric fence includes a test switch, receiving a first output from a monitoring circuit coupled with the circuit of the electric fence, wherein the first output is received when the test switch is closed, opening the test switch and receiving a second output from the monitoring circuit when the test switch is open, comparing the first output and the second output, and assessing the status of the electric fence based on the comparison.

[0005] In another aspect, a method for monitoring a status of an electric fence connected with a power supply includes: disconnecting the electric fence from the power supply, measuring a resistance between a circuit of the electric fence and ground, and assessing the status of the electric fence based on the resistance.

[0006] In yet another aspect, a method for monitoring a status of a railroad wayside electric fence includes assessing an integrity of the electric fence by: providing a current to a circuit of the electric fence, wherein the circuit comprises a test switch, receiving a first output from a monitoring circuit coupled with the circuit of the electric fence, wherein the first output is received when the test switch is closed, opening the test switch and receiving a second output from the monitoring circuit when the test switch is open, and comparing the first output and the second output, and detecting a wire-to-ground short circuit in the electric fence by: disconnecting the electric fence from a power supply, measuring a resistance between the circuit of the electric fence and ground, and assessing the status of the electric fence based on the resistance.

Brief Description of the Drawings

[0007] 

FIG. 1 is a schematic representation of an exemplary system for monitoring the status of an electric fence.

FIG. 2A shows an exemplary method for monitoring the status of an electric fence; and FIG. 2B shows an exemplary circuit diagram for performing the method in FIG. 2A.

FIG. 3A shows another exemplary method for monitoring the status of an electric fence; and FIG. 3B shows an exemplary circuit diagram for performing the method in FIG. 3A.

Detailed Description

[0008] Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the features, as claimed. As used herein, the terms "comprises," "comprising," "having," including," or other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such a process, method, article, or apparatus.

[0009] In this disclosure, relative terms, such as, for example, "about," substantially," and "approximately" are used to indicate a possible variation of ±10% in a stated value. The term "exemplary" is used in the sense of "example" rather than "ideal." As used herein, the singular forms "a," "an," and "the" include plural reference unless the context dictates otherwise.

[0010] FIG. 1 illustrates an exemplary system 100 for monitoring the status of an electric fence 150. As will be explained in detail below, the system may detect wire-to-wire or wire-to-ground short circuits in the electric fence 150. The system 100 may include one or more of a controller 110, an automatic train controller 120, an overhead catenary system 130, one or more junction boxes 140, the electric fence 150, one or more rail tracks 160, and one or more trains 170 on the rail tracks 160. The controller 110 may perform tests to determine the status of the electric fence 150. If the controller 110 detects a fault (e.g., caused by an intruding object) in the electric fence 150, it may send a protection signal to the automatic train controller 120 and/or the overhead catenary system 130, which may then adjust the speed of the train 170 (e.g., stop the train 170) and/or may adjust one or more interlockings to change the directions of the train 170.

[0011] The controller 110 may send signals to the automatic train controller 120, which may include a speed control mechanism in response to the signal from the controller 110. In some cases, the controller 110 may also send signals to the overhead catenary system 130, which may contribute to controlling the speed of or stop the train 170.

[0012] The controller 110 may include any appropriate hardware and software, e.g., one or more data storage devices, one or more processors, memory, communication systems, and/or other appropriate hardware. The processors may be, for example, a single- or multi-core processor, a digital signal processor, microcontroller, a general purpose central processing unit (CPU), and/or other conventional processor or processing/controlling circuit or controller. The memory may include, for example, read-only memory (ROM), random access memory (RAM), flash or other removable memory, or any other appropriate and conventional memory. The communication systems used in the components of the system 100 may include, for example, any conventional wired and/or wireless communication systems such as Ethernet, BLUETOOTH, and/or wireless local area network (WLAN) type systems. Further, the communication systems may include any appropriate and conventional user interface, such as keyboards, keypads, touchscreen interfaces, one or more displays, computer mice, and/or any other suitable user interface.

[0013] Electric fence 150 may include a wire along the perimeter of a railway that maintains a continuous current flow, such that if the electric fence 150 is broken, the current is interrupted. When the current is interrupted, a relay may drop to signal an alarm condition and send a protection signal to the automatic train controller 120 and/or the overhead catenary system 130, which may then adjust the speed of the train 170 (e.g., stop the train 170) and/or may adjust one or more interlockings to change the directions of the train 170. The electric fence 150 may be on one side of the rail track 160. Alternatively or additionally, the electric fence 150 may be on both sides of the rail track 160.

[0014] In some cases, the electric fence 150 may have a plurality of sections. For example, the electric fence 150 shown in FIG. 1 may be a section of a longer electric fence along the rail track 160. Each section the electric fence 150 may be connected with a junction box 140, and the junction boxes 140 connected with the plurality of sections may be connected with a controller 110. Controller 110 may be individual to each section of the electric fence 150, or shared among multiple section of the electric fence 150. When a fault is detected, the controller 110 may identify the section in which the fault occurs. When the electric fence 150 is long, e.g., more than 1, 10, or 100 kilometers in length, the identification of the section having the fault may help a servicing technician locate the fault.

[0015] Electric fence 150 may further include one or more testing mechanisms to detect possible hidden faults in the wire. As previously described, hidden faults may include short-circuits in some points, or in dispersion to ground. FIGs. 2A, 2B, 3A, and 3B provide details on methods to detect the hidden faults. In particular, FIGs. 2A and 2B describe an exemplary method and setup for detecting a failure mode of a wire-to-wire short circuit. FIGs. 3A and 3B describe an exemplary method and setup for detecting a failure mode comprising a short circuit of wire to ground (e.g., in more than one location of the electric fence 150). The tests of FIGs. 2A, 2B, 3A, and 3B may be performed periodically to review the state of electric fence 150.

[0016] FIG. 2A shows an exemplary method 210 for performing a test to determine the integrity of the electric fence 150, and FIG. 2B shows an exemplary circuit diagram for performing the method 210. The test may be performed to determine if the electric fence 150 is broken, e.g., if there is a wire-to-wire short circuit.

[0017] As shown in FIG. 2B, the components in the controller 110 for performing this test may include a relay 111 connected to a circuit of the electric fence 150, a power supply 112, a relay switch 113, and a monitoring circuit 114. In normal operation, test switch 141 may be closed, and the electric fence 150 may be intact. At a default position, when the circuit of electric fence 150 is intact, relay 111 may be energized. At this state, relay switch 113 may be open, rendering monitoring circuit 114 inactive. Because monitoring circuit 114 is inactive, no signal (e.g., no alarm) may be generated from the monitoring circuit 114. The testing mechanism of FIGs. 2A and 2B may include test switch 141 on the circuit of the electric fence 150 (e.g., located at an end of the electric fence 150 away from the controller 110), which may open to interrupt the circuit of electric fence 150. FIGs. 2A and 2B illustrate a test mechanism comprising opening the test switch 141 to evaluate whether electric fence 150 may have a wire-to-wire short circuit.

[0018] Step 211 may include initiating the default state of electric fence 150 by providing a current to the circuit of the electric fence 150, when the test switch 141 is closed. The current may be from the power supply 112.

[0019] Step 212 may include receiving a first output from the monitoring circuit 114. If the electric fence 150 is intact, as discussed above, then the monitoring circuit 114 is expected to be inactive, and the first output may comprise no signal.

[0020] Step 213 may include initiating a test to detect wire-to-wire short-circuiting. Step 213 may include opening the test switch 141 on the electric fence 150. The test switch 141 may be inside a junction box 140. The test switch 141 may be opened in response to a signal from the controller 110. Alternatively or additionally, the test switch 141 may be opened manually, e.g., by a servicing technician.

[0021] Step 214 may include receiving a second output from the monitoring circuit 114. If the electric fence 150 is intact other than the opening of the test switch 141, the circuit of the electric fence 150 may be interrupted by opening of test the switch 141 and the relay 111 may be de-energized. Then the relay switch 113 may be closed and the monitoring circuit 114 may be activated and may generate a signal. In these cases, the second output may comprise the signal from the monitoring circuit 114. If the monitoring circuit 114 provides a signal corresponding in time with the opening of test switch 141 at step 213, the electric fence 150 may be intact. The signal may verify that the relay 111 is functioning as expected and that the electric fence 150 does not have a wire-to-wire short circuit. As used herein, a wire-to-wire short circuit is an undesired joining of wires of the electric fence 150 between its ends, such that the test switch 141 is no longer an active element of the circuit.

[0022] To complete the test, step 215 may include restoring the circuit of the electric fence 215 to its default position. Step 215 may include closing the test switch 141. The test switch 141 may be closed in response to a signal from the controller 110. Alternatively or additionally, the test switch 141 may be closed manually, e.g., by a servicing technician.

[0023] Step 216 may include receiving a third output from the monitoring circuit 114. If the circuit of the electric fence is intact, closing the test switch may restore the current in the circuit of the electric fence 150. Then the relay 111 may be re-energized and the relay switch 113 may be open, which interrupts and inactivates the monitoring circuit 114. In these cases, the third output may comprise no signal from the monitoring circuit 114.

[0024] Step 217 may include assessing the status of the electric fence 150. The assessment may be performed under the control of the controller 110. The assessment may be performed by comparing the first output and the second output, and/or by comparing the second output and the third output. If the electric fence 150 is intact, e.g., does not have a wire-to-wire short circuit, as discussed above, neither the first output nor the third output comprises any signal from the monitoring circuit 114, however, the second output comprises a signal from the monitoring circuit 114 corresponding to the timing of the opening of the test switch 141. Thus, the status of the electric fence 150 may be assessed as normal if one or both of the first output and the second output are different from the second output.

[0025] If the electric fence 150 is broken, in some cases, the circuit of the electric fence 150 may be interrupted and the relay 111 may be de-energized regardless of whether the test switch 141 is open or not. In these cases, the monitoring circuit 114 remains active and the first output, the second output, and the third output trigger the signal from the monitoring circuit 114.

[0026] However, in other cases, when the electric fence 150 is broken or degraded, a wire-to-wire short circuit may be formed that keeps the relay 111 energized or the relay 111 may malfunction to remain energized. In this situation, the relay 111 may remain energized even when test switch 141 is open. In these cases, the monitoring circuit 114 remains inactive and none of the first output, the second output, or the third output triggers a signal from the monitoring circuit 114. When opening the test switch 141 does not trigger a signal from the monitoring circuit 114, the status of the electric fence 150 may be assessed as faulty.

[0027] In the cases where the test is performed on more than one section of the electric fence 150, the method 210 may further include identifying the section where a fault is detected.

[0028] In some cases, steps 213-216 may be repeated. For example, steps 213-216 may be repeated at a time interval ranging from about 5 seconds to about 1 minutes (e.g., from about 10 seconds to about 50 seconds), such as about 5 seconds, about 10 seconds, about 20 seconds, about 30 seconds, about 40 seconds, about 50 seconds, or about 1 minute.

[0029] FIG. 3A shows exemplary method 310 for performing a test to determine whether there is a wire-to-ground short circuit on the electric fence 150, and FIG. 3B shows an exemplary circuit diagram for performing the method 310. The test may be performed to determine if the electric fence 150 is connected with the ground. As shown in FIG. 3B, the components in the controller 110 for performing this test may include a resistance meter 115.

[0030] Step 311 may include disconnecting the electric fence 150 from a power supply, e.g., the power supply 112 in the controller 110 shown in FIG. 2B. The power supply may be disconnected by a switch in the controller 110 (not shown).

[0031] Step 312 may include measuring the resistance between the electric fence 150 and the ground. The resistance may be measured by the resistance meter 115. For example, as shown in FIG. 3B, the resistance meter 115 may be connected to the circuit of the electric fence 150 (with the test switch 141 closed) on one end and to the ground on the other end.

[0032] Step 313 may include assessing the status of the electric fence 150 based on the resistance measured in step 312. The assessment may be performed by comparing the resistance to a reference value. A resistance greater than a reference value (e.g., greater than 1 MΩ) may indicate that there is no wire-to-ground short circuit in the electric fence 150. A resistance that is lower than the reference value or that decreases over time may indicate that there is a wire-to-ground short circuit in the electric fence 150.

[0033] Step 314 may include re-connecting the circuit of the electric fence 150 with the power supply. This step may prevent significant interruption of the function of the electric fence 150 and/or other tests, such as the test illustrated in FIGs. 2A and 2B.

[0034] Steps 311 to 314 may be repeated, e.g., at a fixed time interval. For example, steps 311 to 313 may be repeated at a time interval ranging from about a day to about a month, e.g., once a day, once a week, or once a month.

[0035] One or more types of tests (e.g., the tests illustrated in FIGs. 2A and 3A) may be performed to monitor the electric fence 150. When multiple tests are performed, they may be performed at different frequencies. For example, a test of the integrity of the electric fence 150 may be performed more frequently compared to a test for detecting a wire-to-ground short circuit.

[0036] The one or more tests described herein may include outputting the assessment result of the status of the electric fence 150. The assessment result may indicate the status of the entire electric fence 150, e.g., whether there is any fault in the electric fence 150. In some cases, the assessment result may include identification of the sections of the electric fence 150 having a fault. This information may help a servicing technician locate the fault. The assessment result may be displayed on an interface. For example, the status of each section of the electric fence 150 may be indicated by an LED light. If a given section is assessed as normal, the LED light for that section may be green. When a fault is detected in the section, the LED light for the section may turn red.

[0037] The methods described herein may further include sending a protection signal to a train control system, e.g., the automatic train controller 120 and/or the overhead catenary system 130 (FIG. 1). The protection signal may be generated when one or more of the tests indicate that the electric fence 150 is broken. The train control system may adjust the speed of the train 170 (e.g., stop or reduce the speed of the train 170) or the directions of the train 170 (e.g., by adjusting the interlockings).

Industrial Applicability

[0038] The present disclosure finds potential application in monitoring the status of the electric fence 150 that protects a railroad. The present disclosure enables determining whether the electric fence 150 is broken (e.g., by an intruding object), detecting short circuits in one or more sections of the electric fence 150, and/or identifying the section that is broken or has the short circuit.

[0039] For example, the present disclosure includes methods for monitoring the status of the electric fence 150. In one exemplary method, a current is provided to the circuit of the electric fence 150, and a first output from the monitoring circuit 114 coupled to the circuit of the electric fence 150 is received. Then the test switch 141 on the circuit of the electric fence 150 is open, and a second output from the monitoring circuit 114 is received. Next, the test switch 141 is closed and a third output from the monitoring circuit 114 is received. The status of the electric fence 150 is then assessed based on the first output, the second output, and the third output. In some cases, the status of the electric fence 150 is assessed as faulty if the first output and/or the third output are the same as the second output.

[0040] In another exemplary method, the power supply of the circuit of the electric fence 150 is disconnected and the resistance between the circuit and the ground is measured. The resistance is then compared to a reference value. A resistance greater than a reference value, e.g., 1 MΩ, indicates that the electric fence 150 is normal. A resistance lower than the reference value or a resistance that decreases over time indicates a wire-to-ground short circuit in the electric fence 150.

[0041] A protection signal to the automatic train control system 120 is then generated based on the assessment results. For example, when the tests detect a fault in the electric fence 150, a protection signal is sent to the automatic train control system 120 to stop the train 170 or adjust the interlockings.

[0042] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed system without departing from the scope of the disclosure. Other embodiments of the system will be apparent to those skilled in the art from consideration of the specification and practice of the method disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.

Claims

1. A method for monitoring a status of an electric fence (150), the method comprising:

a. providing a current to a circuit of the electric fence (150), wherein the circuit of the electric fence (150) includes a test switch (141);

b. receiving a first output from a monitoring circuit (114) coupled with the circuit of the electric fence (150), wherein the first output is received when the test switch (141) is closed;

c. opening the test switch (141) and receiving a second output from the monitoring circuit (114) when the test switch (141) is open;

d. comparing the first output and the second output; and

e. assessing the status of the electric fence (150) based on the comparison.

2. The method of claim 1, wherein the status of the electric fence (150) is assessed as faulty if the first output and the second output are the same, or the second and the third outputs are the same.

3. The method of claim 1 or 2, wherein the second output comprises a signal indicative of interruption of the electric fence (150).

4. The method of any of claims 1-3, wherein the monitoring circuit (114) is coupled with the circuit of the electric fence (150) via a relay (111).

5. The method of any of claims 1-4, further comprising sending the assessed status to a train controller.

6. The method of claim 5, wherein the train controller is an automatic train controller (120), an overhead catenary system (130), or a combination thereof.

7. The method of any of claims 1-6, wherein the electric fence (150) has a length of more than 1 kilometer.

8. The method of any of claims 1-7, wherein the electric fence (150) is between a rail track (160) and a road.

9. The method of claim 8, further comprising adjusting a speed of a train (170) on the rail track (160) based on the assessed status of the electric fence (150).

10. The method of claim 8 or 9, further comprising adjusting an interlocking of the rail track (160).

Drawing