CN210923925U

CN210923925U - C interface cable fault detection device of LEU

Info

Publication number: CN210923925U
Application number: CN201921156380.2U
Authority: CN
Inventors: 石玉彬; 李丹; 苏杰
Original assignee: Hangzhou Weilian Jingtai Technology Co ltd
Current assignee: Beijing Jiaoda Microunion Tech. Co.,Ltd.
Priority date: 2019-07-24
Filing date: 2019-07-24
Publication date: 2020-07-03
Anticipated expiration: 2029-07-24

Abstract

The utility model discloses a device of LEU's C interface cable fault detection. The utility model discloses a device includes: three directional coupling circuit modules of transformer: collecting incident waves and reflected waves of a C interface output signal C6 signal of an LEU; a filter circuit module: filtering high-frequency interference waves of incident waves and reflected waves; the voltage sampling circuit module: collecting voltage signals of incident waves and reflected waves; phase difference acquisition circuit module: acquiring zero crossing points of incident waves and reflected waves to obtain a phase time difference; the signal processing module: processing the voltage signal and the phase difference information, judging the connection state of a C interface cable of the LEU, and calculating the position of a fault point if the LEU has an open circuit fault or a short circuit fault; a serial port communication module: reporting the state information of the C interface cable; a display module: and displaying the state information of the C interface cable. The circuit provided by the invention applies the cable reflection principle, and the cable fault detection can be realized only by the voltage relation and the phase relation.

Description

C interface cable fault detection device of LEU

Technical Field

The invention relates to LEU equipment of a transponder transmission system in a railway signal system, belongs to the technical field of cable detection, and particularly relates to a device for detecting faults of a C-interface cable of an LEU.

Background

Technical conditions of TB/T3485-. Allowing a module or component of equipment external to the LEU to cooperate with the LEU to perform long-reach cable condition detection functions. The function ensures that the LEU can timely find whether a responder cable connected with the responder by the LEU has a fault or not, and once the cable fault, such as an open circuit or a short circuit, is detected, the device can timely find the cable fault and judge the fault type and the distance between a fault point and the LEU.

Disclosure of Invention

The invention aims to provide a device for detecting faults of a C interface cable of an LEU (electronic equipment unit) aiming at the design requirement that the LEU equipment has a cable open/short circuit detection function. Not only can detect the normal, open circuit and short circuit state of the transponder cable, but also can detect the distance between a fault point and an LEU during fault.

The purpose of the invention can be realized by the following technical scheme: an apparatus for C interface cable fault detection of an LEU includes: the three-transformer directional coupling circuit module, the filter circuit module, the voltage sampling circuit module, the phase difference acquisition circuit module, the signal processing module, the serial port communication module and the display module.

The three-transformer directional coupling circuit module is used for collecting incident waves and reflected waves of a C interface output signal C6 signal (8.82kHz sine wave) of the LEU.

The filter circuit module is used for filtering high-frequency interference waves (output signals C1 signals in a C interface and 564.48kHz DBPL coded signals) of incident waves and reflected waves to obtain incident waves and reflected waves of C6 signals of a C interface of an LEU.

The voltage sampling circuit module is used for collecting voltage signals of incident waves and reflected waves of the C6 signals.

The phase difference acquisition circuit module is used for acquiring zero-crossing points of incident waves and reflected waves of the C6 signals to obtain the phase time difference of the incident waves and the reflected waves of the C6 signals.

The signal processing module is used for processing voltage signals and phase difference information of incident waves and reflected waves of the collected C6 signals, judging the connection state of a C interface cable of the LEU, judging open-circuit and short-circuit faults and calculating the position of a fault point.

And the serial port communication module is used for reporting the state information of the C interface cable.

The display module is used for displaying and displaying the state information of the C interface cable.

Drawings

FIG. 1 is a schematic view of the structure of the apparatus of the present invention

FIG. 2 is a schematic flow chart of the method of the present invention

FIG. 3 shows the waveforms of incident and reflected waves in the open state with L equal to 0

FIG. 4 shows waveforms of incident wave and reflected wave in the open state, where L is not equal to 0

FIG. 5 shows the waveforms of incident and reflected waves in the short-circuited state, where L is 0

FIG. 6 shows the waveforms of incident and reflected waves in the short-circuited state, where L is not equal to 0

Detailed Description

The core idea of the invention is that the incident wave and the reflected wave of the C interface output signal C6 signal (8.82kHz sine wave) of the LEU are collected by the three-transformer directional coupling circuit, the reflection principle of the transmission cable is utilized, the relation between the peak voltage of the incident wave and the reflected wave of the C6 signal is analyzed to judge whether the cable is in a fault state, if the cable is in the fault state, the phase relation between the incident wave and the reflected wave of the C6 signal is analyzed to judge whether the cable is in an open-circuit fault or a short-circuit fault, and the distance between a fault point and the LEU is further determined. A method for implementing a device for detecting faults of a C interface cable of an LEU (line terminal Unit) comprises the following steps:

step 1: the incident wave and the reflected wave of the C interface output signal C6 signal (8.82kHz sine wave) of the LEU are collected.

Step 2: the interference signals (C1 signals) of the incident wave and the reflected wave of the C6 signals are filtered.

And step 3: and processing the incident wave and the reflected wave of the C6 signal to obtain the time difference between the peak voltage and the zero crossing point.

And 4, step 4: and analyzing the state of the cable of the responder, and if the state is judged to be a normal state, not performing the following steps, and if the state is judged to be a fault state, performing the subsequent steps.

And 5: the fault status of the cable (open or short) is analyzed, and the distance of the fault point from the LEU is analyzed.

Further, the analyzing the state of the transponder cable in step 4 specifically includes: judging the peak voltage relationship between the incident wave and the reflected wave of the C6 signal obtained in the step 3, and if the peak voltage of the transmitted wave is smaller than a threshold value relative to the peak value of the incident wave, judging that the state of the C interface cable of the LEU is normal (when the load is a transponder or an equivalent load); and if the peak voltage of the transmitted wave is smaller than the threshold value relative to the peak voltage of the incident wave, judging that the cable of the C interface of the LEU has a state fault (open circuit or short circuit).

Further, when it is determined that the cable state is faulty, analyzing the fault state and the fault point distance in step 5 specifically includes:

step 5.1, according to the time difference between the zero-crossing point of the reflected wave of the C6 signal and the zero-crossing point of the incident wave in step 3, if the time difference Δ t satisfies: when the delta T is more than or equal to 0 and less than or equal to T/2, (T represents the period of the C6 signal, and T is 113.4 mu s), the cable fault is judged to be an open-circuit fault; if the time difference Δ t satisfies: and when T/2 is more than or equal to delta T and less than or equal to T, judging the cable fault as a short-circuit fault.

Step 5.2, calculating the distance between the fault point and the LEU, and if the cable fault is an open-circuit fault, multiplying the half of the time difference delta t by the propagation speed v of the signal in the cable to obtain the distance between the open-circuit fault point; and if the cable fault is a short circuit, multiplying the half of the time difference delta T minus T/2 by the propagation speed v to obtain the short circuit fault point distance.

The principle of the detection method provided by the embodiment includes the following three aspects, the first aspect is the judgment of the cable state, the second aspect is the judgment of the open circuit and short circuit of the cable fault state, and the third aspect is the judgment of the fault point distance.

TB/T3100.6-2017 transponder data transmission cable5.9.1 specifies that the pair attenuation of the transponder system transmission cable is less than or equal to 0.8 dB/km. Technical conditions for the transmission system of TB/T3485 and 2017 transponders define the maximum cable length of the interface C to be 2500 m. When the cable has short circuit or open circuit fault at 2.5km, the monitored reflected wave V_DRelative to the incident wave V_CThe attenuation of (2) is maximum, at which the attenuation value is 0.8dB/km × 2.5km × 2 is 4dB, i.e. the reflected wave energy P2 is equal to 0.4 times the incident wave energy P1, so V is equal to_D＝0.63V_CIn which V is_CRepresenting the incident wave voltage, V_DRepresenting the reflected wave voltage. Within the range of 0-2.5 km, when the cable has short circuit or open circuit fault, V_D≥0.63V_C. The cable state of the C interface of the LEU is normal (when the load is a responder or an equivalent load); v_DIs obviously less than 0.63V_C. And judging whether the cable is in an open short circuit state or not according to the level relation of the reflected wave and the incident wave.

Second, as shown in fig. 3 and 4, when the cable is opened, the cable is reflected, and the reflection coefficient is 1, that is, at the fault point, the reflection level is equal to the incident level in amplitude and phase. As shown in fig. 5 and 6, when the cable is opened, the cable is reflected, and the reflection coefficient is 1, that is, at the fault point, the reflection level is equal to the incident level in amplitude and same in phase. An open circuit state:

Δt＝2L/v

0≤Δt≤(2×2.5km)/(0.14km/μs)＝35.7μs

wherein L represents the distance of an open circuit point and is in km; v represents the wave velocity, here taken at 0.14km/μ s. Δ t represents the difference in phase time between the reflected and incident waves monitored by the ECI.

Therefore, Δ t is not less than 0 but not more than 35.7 μ s.

Short-circuit state:

Δt＝T/2+2L/v

113.4μs/2≤Δt≤113.4μs/2+(2×2.5km)/(0.14km/μs)

in the formula, T represents the period of C6(8.82k sine wave) and is 113.4. mu.s.

Δ t represents the difference in phase time between the reflected and incident waves monitored by the ECI.

Therefore, the delta t is less than or equal to 56.7 mu s and less than or equal to 92.4 mu s.

In conclusion, the phase time difference between the reflected wave and the incident wave monitored by the ECI can be used for judging whether the transmission cable of the transponder system is in an open circuit or a short circuit in a 2.5km fault state.

And thirdly, judging the distance between the fault point and the LEU, and analyzing the distance of the fault point according to the time difference of the reflected wave and the incident wave if the cable fault is an open-circuit fault.

An open circuit state:

L＝1/2×v×Δt；

short-circuit state:

L＝1/2×v×(Δt-T/2)。

Claims

1. a device for detecting faults of a cable of an interface C of an LEU (Long term Unit) is characterized in that: a device for detecting faults of a cable of a C interface of an LEU (low-level integrated circuit) is composed of a three-transformer directional coupling circuit module, a filter circuit module, a voltage sampling circuit module, a phase difference acquisition circuit module, a signal processing module, a serial port communication module and a display module.

2. The apparatus of claim 1, wherein the apparatus for detecting cable faults of the C interface of the LEU comprises: and collecting incident waves and reflected waves of a C interface output signal C6 signal of the LEU, wherein the C6 signal is a sine wave of 8.82 kHz.

3. The apparatus of claim 1, wherein the apparatus for detecting cable faults of the C interface of the LEU comprises: and filtering high-frequency interference waves of the incident waves and the reflected waves by a low-pass filter circuit to obtain the incident waves and the reflected waves of the C6 signal of the C interface of the LEU, wherein the high-frequency interference waves are the C1 signal of 564.48kHz output from the C interface.

4. The apparatus of claim 1, wherein the apparatus for detecting cable faults of the C interface of the LEU comprises: and acquiring voltage signals of incident waves and reflected waves of the C6 signals.

5. The apparatus of claim 1, wherein the apparatus for detecting cable faults of the C interface of the LEU comprises: and acquiring zero-crossing points of the incident wave and the reflected wave of the C6 signal to obtain the phase time difference of the incident wave and the reflected wave of the C6 signal.

6. The apparatus of claim 1, wherein the apparatus for detecting cable faults of the C interface of the LEU comprises: the method comprises the steps of processing voltage signals and phase difference information of incident waves and reflected waves of collected C6 signals, judging the connection state of a C interface cable of an LEU, judging open-circuit and short-circuit faults, and calculating the positions of fault points.

7. The apparatus of claim 1, wherein the apparatus for detecting cable faults of the C interface of the LEU comprises: and reporting the state information of the C interface cable.

8. The apparatus of claim 1, wherein the apparatus for detecting cable faults of the C interface of the LEU comprises: and the status information of the C interface cable is displayed through the LED indicating lamp.