CN105676066B - A kind of cable fault positioning examination device and method - Google Patents

Abstract

The present invention provides a cable fault location and troubleshooting method and device, wherein the cable fault location and troubleshooting method is used in a cable fault location and troubleshooting device, and the cable fault location and troubleshooting device includes a high voltage DC signal generator connected to the cable to be tested and signal detection equipment connected to the cable to be tested; the cable fault location troubleshooting method includes: a high-voltage direct current signal generator sends a high-voltage direct current signal to the cable to be tested; using the signal detection equipment to detect the reflection of the cable to be tested The high-impedance fault reflection pulse and detection time; according to the time interval between the high-impedance fault reflection pulse and the high-voltage direct current signal and the propagation speed of the high-impedance fault reflection pulse, calculate the cable high-impedance fault point to the cable fault Positioning device distance. The technical scheme of the invention can timely and effectively check and locate the high-resistance fault of the cable.

Description

Device and method for cable fault location and troubleshooting

technical field

The invention relates to the technical field of cable fault troubleshooting, and more specifically, to a device and method for cable fault location and troubleshooting.

Background technique

High-voltage power cables are indispensable and important equipment in power supply systems, especially in places where there are many buildings on the surface and require overall beauty and equipment safety, overhead lines are often replaced by cables buried underground. The most commonly used method of laying high-voltage power cables is to excavate nearly 1m deep earth and directly bury them underground, inject yellow sand around the cables, and then cover them with bricks for protection. This method is used for users with many cables on the same road. Because the cable is buried underground, after long-term consumption, corrosion and wear, the cable is prone to faults. The main faults include low-resistance faults and high-resistance faults. At the same time, because the cables are buried underground, once the cable fails, it is not easy Locating and checking.

In the related art, for cable faults, low-voltage pulses are generally used to test cable faults to troubleshoot and locate low-resistance faults (such as open circuits, short circuits, etc.), but for high-resistance faults of cables, reflections obtained by using low-voltage pulse detection methods The pulse is almost zero, therefore, it is difficult for the above-mentioned method to troubleshoot and locate the high-resistance fault of the cable in a timely and effective manner.

To sum up, how to quickly and effectively troubleshoot and locate the high-resistance fault of the cable has become a technical problem to be solved urgently by those skilled in the art.

Contents of the invention

The purpose of the present invention is to provide a generation scheme of SVG/CIM files based on spatial data, so as to solve the problem that it is difficult to timely and effectively troubleshoot and locate high-resistance faults of cables in the prior art introduced in the background art.

In order to solve the above technical problems, the present invention provides the following technical solutions:

The invention provides a cable fault location and troubleshooting method, which is characterized in that it is used in a cable fault location and troubleshooting device, and the cable fault location and troubleshooting device includes a high-voltage DC signal generator connected to the cable to be tested and a high-voltage DC signal generator connected to the cable to be tested. Connected signal detection equipment; the cable fault location troubleshooting method includes:

The high-voltage DC signal generator sends a high-voltage DC signal to the cable to be tested;

Using the signal detection device to detect the high-impedance fault reflection pulse and detection time reflected by the cable to be tested;

Calculate the distance from the cable high-resistance fault point to the cable fault location device according to the time interval between the high-resistance fault reflection pulse and the high-voltage direct current signal and the propagation speed of the high-resistance fault reflection pulse.

Preferably, the cable fault location and troubleshooting device further includes a low-voltage pulse signal generator, and the cable fault location and troubleshooting method further includes:

The low-voltage pulse signal generator sends a low-voltage pulse transmission signal to the cable to be tested;

Detecting the low-impedance fault reflected pulse returned by the cable to be tested;

The distance from the cable fault point to the cable fault location device is calculated according to the time interval between the low-resistance fault reflection pulse and the low-voltage pulse transmission signal and the propagation speed of the low-resistance fault reflection pulse.

Preferably, the cable fault location and troubleshooting method further includes:

Judging the polarity of the low-impedance fault reflection pulse returned by the cable to be tested;

If the reflected pulse of the low-resistance fault is positive, it is determined that the cable fault is an open circuit fault;

If the reflected pulse of the low-resistance fault is negative, it is determined that the cable fault is a short-circuit fault.

Preferably, the cable fault location and troubleshooting method further includes:

Obtaining in advance the distance between the cable terminal to be tested and the cable fault location and troubleshooting device;

Using the low-voltage pulse signal generator to send a low-voltage pulse transmission signal to the cable under test;

If the positive polarity pulse returned by the cable to be tested is detected; then calculate the distance between the positive polarity pulse generation point and the cable fault location device;

If the difference between the distance between the cable terminal to be tested and the cable fault locating device and the distance between the positive polarity pulse generation point and the cable fault locating device is greater than or equal to a predetermined distance, then it is determined that the cable fault is an open circuit Fault.

Preferably, the cable fault location and troubleshooting method further includes:

Using the low-voltage pulse signal generator to send a low-voltage pulse transmission signal to the cable under test;

If the low-impedance fault reflection pulse is not detected, switch to the high-voltage direct current signal generator, and use the high-voltage direct current signal generator to send a high-voltage direct current signal to the cable to be tested;

If the high-impedance fault reflection pulse reflected by the cable under test is detected, it is determined that a high-impedance fault occurs in the cable under test; if the high-impedance fault reflection pulse reflected by the cable under test is not detected, then it is determined that the The test cable is faultless.

According to the second aspect of the present invention, a cable fault location and troubleshooting device is also provided, and the cable fault location and troubleshooting device includes:

A high-voltage direct current signal generator, the high-voltage direct current signal generator and the monitoring point of the cable to be tested are electrically connected through a first line, and are used to send a high-voltage direct current signal to the cable to be tested;

A signal detection device, the signal detection device is connected to the first line through a second line, and is used to detect the high-impedance fault reflection pulse and detection time reflected by the cable to be tested;

The signal detection device includes a DC blocking capacitor, a sampling resistor, and a waveform display connected in parallel with the sampling resistor in sequence from the connection point of the first line and the second line; the waveform display is used to detect and display The high-voltage direct current signal, the high-impedance fault reflection pulse, and the detection time respectively corresponding to the high-voltage direct current signal and the high-impedance fault reflection pulse.

Preferably, the cable fault location and troubleshooting device further includes:

A distance calculator, connected to the signal detection device, used to calculate the time interval between the high-impedance fault reflection pulse and the high-voltage direct current signal according to the detection time corresponding to the high-voltage direct current signal and the high-impedance fault reflection pulse respectively It is also used to calculate the distance between the cable high-resistance fault point and the cable positioning device according to the time interval between the high-resistance fault reflection pulse and the high-voltage direct current signal and the propagation speed of the high-resistance fault reflection pulse.

Preferably, the cable fault location and troubleshooting device further includes:

A low-voltage pulse signal generator, the low-voltage pulse signal generator is electrically connected to the cable under test through the first line, and is used to send a low-voltage pulse signal to the cable under test;

The first line is also provided with a signal generator switching switch;

The signal detection device is also used to detect the low-impedance fault reflection pulse returned by the cable to be tested;

The distance calculator is also used to calculate the cable fault point to the cable fault location device according to the time interval between the low-resistance fault reflection pulse and the low-voltage pulse transmission signal and the propagation speed of the low-resistance fault reflection pulse the distance.

Preferably, the initial state of the signal generator switching switch is connected to the low-voltage pulse signal generator;

The signal generator is also used to switch to the high-voltage DC signal generator and communicate with the high-voltage DC signal generator if the signal detection device does not detect the low-impedance fault reflection pulse;

The cable fault location and troubleshooting device also includes a discriminator; the discriminator is used to determine that a high-impedance fault occurs in the cable to be tested if the signal detection device detects a high-impedance fault reflection pulse reflected by the cable to be tested; The discriminator is further configured to determine that the cable to be tested has no fault if the signal detection device does not detect the high-impedance fault reflection pulse reflected by the cable to be tested.

Preferably, the cable fault location and troubleshooting device further includes:

sequentially connected to the reverse diode and the current limiting resistor of the first line from the high voltage direct current signal generator;

A shunt resistor connected between the DC blocking capacitor and the sampling resistor.

Through the above working process, it can be concluded that the cable fault location and troubleshooting solution provided by the present invention uses a high-voltage direct current signal generator to send a high-voltage direct current signal to the cable to be tested, and continuously increases the voltage of the high-voltage direct current signal through the high-voltage direct current signal generator until Break down the cable under test with a high-resistance fault, and a short-circuit arc will be formed at the fault point to generate a reverse pulse signal. Because the voltage of the high-voltage DC signal is relatively high, when the cable has a high-resistance fault, the cable under test will be struck. The signal detection equipment can detect the high-frequency high-impedance fault reflection pulse reflected by the cable to be tested, and multiply the time interval between the high-impedance fault reflection pulse and the high-voltage DC signal by the propagation speed of the high-impedance fault reflection pulse, and then Take 1/2 to get the distance from the cable fault point to the cable fault location device. In this scheme, a high-voltage DC signal generator is used instead of a low-voltage pulse signal generator to transmit a high-voltage DC signal, and the pulse reflected by the cable under test with a high-impedance fault can be obtained. Signal, so as to promptly and quickly troubleshoot and locate the high-resistance fault of the cable.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings that need to be used in the description of the embodiments will be briefly introduced below. Other drawings can also be obtained based on these drawings.

Fig. 1 is a schematic flow chart of a cable fault location and investigation method provided by an embodiment of the present invention;

Fig. 2 is a schematic flowchart of a cable fault location and troubleshooting method provided by an embodiment of the present invention;

Fig. 3 is a schematic flowchart of a cable fault location and troubleshooting method provided by an embodiment of the present invention;

4 is a schematic flowchart of a cable fault location and troubleshooting method provided by an embodiment of the present invention;

5 is a schematic flowchart of a cable fault location and troubleshooting method provided by an embodiment of the present invention;

Fig. 6 is a schematic structural diagram of a cable fault location and troubleshooting device provided by an embodiment of the present invention;

Fig. 7 is a schematic structural diagram of a cable fault location and troubleshooting device provided by an embodiment of the present invention;

Fig. 8 is a schematic structural diagram of a cable fault location and troubleshooting device provided by an embodiment of the present invention;

FIG. 9 is a schematic waveform diagram of a low-resistance fault provided by an embodiment of the present invention;

Fig. 10 is a schematic waveform diagram of a cable short-circuit fault provided by an embodiment of the present invention;

Fig. 11 is a schematic waveform diagram of a cable high-resistance fault provided by an embodiment of the present invention.

Detailed ways

The cable fault locating and checking solution provided by the embodiment of the present invention solves the problem that it is difficult to timely and effectively check and locate the high-resistance fault of the cable introduced in the background art.

In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, and to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention are described below in conjunction with the accompanying drawings The program is described in further detail.

Please refer to accompanying drawing 1, which is a schematic flowchart of a method for locating and troubleshooting a cable fault according to an exemplary embodiment of the present invention. The cable fault location and troubleshooting method provided by the embodiment of the present invention is used in the cable fault location and troubleshooting device shown in Figure 9, the cable fault location and troubleshooting device includes a high-voltage DC signal generator connected to the cable to be tested and a The signal detection equipment connected to the measuring cable; the cable fault location troubleshooting method comprises the steps:

S110: the high-voltage DC signal generator sends a high-voltage DC signal to the cable to be tested;

S120: Use the signal detection device to detect the high-impedance fault reflection pulse reflected by the cable to be tested and the detection time; wherein, the detection time includes the time when the high-impedance fault reflection pulse is detected and the starting time for sending the high-voltage DC signal, which is For convenience of calculation, the starting time can be set to 0.

By using a high-voltage DC signal generator to send a high-voltage DC signal to the cable under test, the cable under test can return reflected pulses, and by detecting the waveform of the reflected pulses, it can be judged whether the cable under test has a high-resistance fault.

S130: Calculate the distance from the cable high-resistance fault point to the cable fault location device according to the time interval between the high-resistance fault reflection pulse and the high-voltage direct current signal and the propagation speed of the high-resistance fault reflection pulse.

When a high-resistance fault occurs in the cable to be tested, the distance from the cable high-resistance fault point to the cable fault location device can be calculated according to the time interval between the high-resistance fault reflection pulse and the high-voltage DC signal and the propagation speed of the high-resistance fault reflection pulse. Therefore, it is convenient for relevant operators to promptly and quickly realize the investigation and positioning of high-resistance faults of cables.

Specifically, calculate the distance between the high-resistance fault point and the cable fault location device according to the formula L=V×t/2, wherein L is the distance between the test point (i.e. the position of the cable fault location device) and the fault point of the cable to be tested, V is the propagation velocity of the high-impedance fault reflection pulse, t is the time interval from the transmission of the high-voltage DC signal to the return of the high-impedance fault reflection pulse from the high-impedance fault point, and R is the inductance value per unit length of the cable to be tested, and C is the capacitance value per unit length of the cable to be tested, both of which are parameters of the cable that can be found.

Through the above working process, it can be concluded that the cable fault location and troubleshooting solution provided by the present invention uses a high voltage DC signal generator to send a high voltage DC signal to the cable to be tested. Since the voltage of the high voltage DC signal is relatively high, when the cable has a high resistance When a fault occurs, the signal detection equipment can detect the high-frequency high-impedance fault reflection pulse reflected by the cable to be tested. By calculating the time interval between the high-impedance fault reflection pulse and the high-voltage direct current signal and multiplying the propagation speed of the high-impedance fault reflection pulse, Then take 1/2 to get the distance from the cable fault point to the cable fault location device. In this scheme, a high-voltage DC signal generator is used instead of a low-voltage pulse signal generator to transmit a high-voltage DC signal, which can obtain the reflection of the cable under test with a high-impedance fault. Pulse signal, so that it is convenient to locate and check the high-resistance fault point of the cable in time and quickly.

In addition, because the cable to be tested is buried underground, the cable to be tested is prone to low-resistance faults such as short circuits. Therefore, the cable fault location and troubleshooting device also includes a low-voltage pulse signal generator, which can detect the low-resistance of the cable by sending a low-voltage pulse signal. Fault, as shown in Figure 2, the cable fault location and troubleshooting method provided by the embodiment of Figure 2, in addition to the steps shown in Figure 1, also includes:

S210: the low-voltage pulse signal generator sends a low-voltage pulse transmission signal to the cable to be tested;

S220: Detect the low-impedance fault reflection pulse returned by the cable under test.

Send a low-voltage pulse transmission signal to the cable under test through the low-voltage pulse signal generator. If the cable under test fails, the cable under test can reflect back the fault reflection signal, and the waveform of the low-impedance fault reflection signal can be received and detected by the signal detection device. Accurately determine whether the cable under test has a low-resistance fault.

S230: Calculate the distance from the cable fault point to the cable fault location device according to the time interval between the low-resistance fault reflection pulse and the low-voltage pulse transmission signal and the propagation speed of the low-resistance fault reflection pulse.

When it is determined that a low-resistance fault occurs in the cable to be tested, by detecting the time interval between the low-resistance fault reflection pulse and the low-voltage pulse transmission signal and the propagation speed of the low-resistance fault reflection pulse, the distance from the cable fault point to the cable fault location device can be calculated. Distance, so that the low-resistance fault of the cable can be located in time and quickly. For the specific calculation method, please refer to the distance calculation formula for high-resistance faults.

In fact, when using the low-voltage pulse method for fault detection, the terminal of the cable to be tested will also reflect the signal, so in order to facilitate the calculation of the distance and eliminate interference, the cable fault location device can be set at one end of the cable to be tested, and the cable to be tested can be known in advance. total length.

In addition, when using low-voltage pulses to detect faults in the cable under test, the pulse polarity of the open-circuit fault and the short-circuit fault are different. Therefore, in order to accurately determine whether the cable under test is a high-resistance fault or a low-resistance fault, as shown in Figure 3, Fig. 3 In addition to the steps shown in Figures 1 and 2, the cable fault location and investigation method in the embodiment also includes:

S310: judging the polarity of the low-impedance fault reflection pulse returned by the cable to be tested;

Please refer to Figure 9, the polarity of the reflected pulse of the low-resistance fault, that is, the change trend of the pulse amplitude, is reflected in the waveform display, that is, the orientation of the waveform where the pulse is located.

S320: If the reflected pulse of the low-impedance fault is positive, then determine that the cable fault is an open circuit fault;

The resistance value of the open circuit fault is positive infinity, which can reflect the positive polarity low-voltage pulse. Therefore, the open circuit fault of the cable to be tested can be detected through the judging method in step S320.

S330: If the reflected pulse of the low-impedance fault is negative, determine that the cable fault is a short-circuit fault.

By judging the polarity of the low-impedance fault reflected pulse, the type of the cable fault to be tested can be quickly and accurately judged. Since the cable to be tested is buried underground, the method of judging the polarity of the low-impedance fault reflected pulse is easy to operate and easy to use. The structure is simple, and the rapid detection of the fault type can be realized.

As shown in Figure 9, when the low-voltage pulse method is used to detect cable faults, the terminal of the cable to be tested will also reflect a positive pulse signal. Therefore, in order to eliminate the interference of terminal reflected pulses on the judgment of open circuit faults, please refer to Figure 4 and implement in Figure 4. In addition to the method steps shown in Figure 1 and Figure 2, the cable fault location and troubleshooting method in the example also includes:

S410: Obtain in advance the distance between the cable terminal to be tested and the cable fault location and troubleshooting device;

By pre-obtaining the distance between the cable terminal to be tested and the cable fault location and troubleshooting device, when using the low-voltage pulse method to measure low-resistance faults, when a positive reflected pulse is detected, it can be judged by the distance whether the reflected pulse is reflected by the terminal. Therefore, when it is judged that it is the reflected pulse of the terminal, the possibility of an open circuit fault is excluded.

S420: Use the low-voltage pulse signal generator to send a low-voltage pulse transmission signal to the cable under test;

S430: If the positive polarity pulse returned by the cable under test is detected, calculate the distance between the positive polarity pulse generation point and the cable fault location device;

S440: If the difference between the distance between the cable terminal to be tested and the cable fault locating and checking device and the distance between the positive polarity pulse generating point and the cable fault locating device is greater than or equal to a predetermined distance, determine that the cable is faulty for an open circuit fault.

When the difference between the distance between the cable terminal to be tested and the cable fault location and investigation device and the distance between the positive pulse generation point and the cable fault location device is greater than or equal to the predetermined distance, it means that the pulse generation point is not the cable terminal to be tested, so it can be determined The cable under test is an open circuit fault. Therefore, through the above method, the open circuit fault of the cable to be tested can be judged timely and effectively. At the same time, if an open circuit fault occurs at the terminal position, the positive polarity pulse of the cable under test can be detected by using the dichotomy method on the side close to the terminal, and the positive polarity pulse signal reflected by the open circuit fault can be gradually found or eliminated.

In actual operation, if the cable to be tested has a fault, it is not possible to determine whether the fault of the electrical test cable is a high-resistance fault or a low-resistance fault. Therefore, in order to quickly determine the fault type of the cable, as shown in Figure 5, the implementation In addition to the steps shown in Figure 1 and Figure 2, the cable fault location and troubleshooting method in the example also includes:

S510: Use the low-voltage pulse signal generator to send a low-voltage pulse transmission signal to the cable under test;

First, judge whether a low-resistance fault occurs by sending a low-voltage pulse signal.

S520: If the low-impedance fault reflection pulse is not detected, switch to the high-voltage direct current signal generator, and use the high-voltage direct current signal generator to send a high-voltage direct current signal to the cable to be tested;

S530: If the high-impedance fault reflection pulse reflected by the cable under test is detected, it is determined that a high-impedance fault occurs in the cable under test; if the high-impedance fault reflection pulse reflected by the cable under test is not detected, then it is determined that the The cable under test is faultless. If the cable under test does not have a high-impedance fault, the waveform detected by the signal detection equipment will not fluctuate violently, so the normal fluctuation waveform can be ignored.

If the low-impedance fault reflection pulse is not detected, that is, the waveform is as shown in the good cable waveform in Figure 9, it means that the cable is not faulty or the cable has a high-impedance fault. At this time, switch to the high-voltage DC signal generator and send a signal to the cable under test High-voltage DC signal to detect whether the cable under test returns a high-impedance fault reflection pulse. If no high-impedance fault reflection pulse is returned, the cable under test is not faulty. If a high-impedance fault reflection pulse is detected, it means the cable under test When a high-resistance fault occurs, the position of the high-resistance fault of the cable to be tested can be accurately located by using the distance calculation method in step S130 shown in FIG. 1 .

Based on the same inventive concept, the embodiment of the present application also provides a cable fault location and troubleshooting device. Since the method corresponding to the device is the cable fault location and troubleshooting method in the embodiment of the application, and the principle and method of the device to solve the problem are similar, therefore For the implementation of the device, reference may be made to the implementation of the method, and repeated descriptions will not be repeated.

Please refer to FIG. 6. FIG. 6 is a schematic structural diagram of a cable fault location and troubleshooting device shown in an exemplary embodiment of the present invention. As shown in FIG. 6, the cable fault location and troubleshooting device includes:

High-voltage DC signal generator 61, the monitoring point of the high-voltage DC signal generator 61 and the cable 62 to be tested are electrically connected through the first line 63, and the high-voltage DC signal generator 61 is used to send a high-voltage DC signal to the cable 62 to be tested ;

A signal detection device 64, the signal detection device 64 is connected to the first line 63 through a second line 65, and is used to detect the high-impedance fault reflection pulse and detection time reflected by the cable 62 to be tested;

The signal detection device 64 includes a DC blocking capacitor 641, a sampling resistor 642, and a waveform display 643 connected in parallel with the sampling resistor 642, which are sequentially connected from the connection point of the first line 63 and the second line 65; The waveform display 643 is used to detect and display the high-voltage direct current signal, the high-impedance fault reflection pulse, and the detection time respectively corresponding to the high-voltage direct current signal and the high-impedance fault reflection pulse.

By using the high-voltage DC signal generator 61 to send a high-voltage DC signal to the cable 62 to be tested, because the voltage of the high-voltage DC signal is relatively high, it can break down the cable to be tested with a high-impedance fault, so when a high-impedance fault occurs in the cable 62, The signal detection device 64 can detect the high-frequency high-impedance fault reflection pulse reflected by the cable 62 to be tested. Since the DC blocking capacitor 641 has the characteristics of blocking DC and communicating AC, and the resistance of the DC blocking capacitor 641 is relatively large, the high-impedance fault The reflected pulse can pass through the DC-blocking capacitor 641 and affect the sampling voltage of the sampling resistor. The waveform display 643 can detect the high-impedance fault reflected pulse, and further calculate the time interval between the high-impedance fault reflected pulse and the high-voltage direct current signal. Multiply by the propagation speed of the high-impedance fault reflection pulse, and then take 1/2 of the product result to get the distance from the cable fault point to the cable fault location device. This program uses a high-voltage DC signal generator instead of a low-voltage pulse signal generator to emit high-voltage DC The signal can obtain the pulse signal reflected by the cable under test with a high-impedance fault, and further investigate and locate the high-impedance fault of the cable in a timely and rapid manner.

As shown in Figure 7, the cable fault location troubleshooting device shown in Figure 6 also includes:

A distance calculator 66, connected to the signal detection device 64, used to calculate the distance between the high-impedance fault reflection pulse and the high-voltage direct current signal according to the detection time corresponding to the high-voltage direct current signal and the high-impedance fault reflection pulse respectively. Time interval; it is also used to calculate the distance between the cable high-resistance fault point and the cable positioning device according to the time interval between the high-resistance fault reflection pulse and the high-voltage direct current signal and the propagation speed of the high-resistance fault reflection pulse . The distance between the cable high-resistance fault point and the cable positioning device calculated by the distance calculator 66 can be displayed on the waveform display 643 , as shown in FIG. 11 , to help relevant operators to locate.

Specifically, the distance between the high-resistance fault point and the cable fault location device is calculated according to the formula L=V×t/2, where L is the distance from the test point (that is, the cable fault location device) to the fault point, and V is the high-resistance fault reflection The propagation speed of the pulse, t is the time interval from the transmission of the high-voltage DC signal to the return of the high-impedance fault reflection pulse from the high-impedance fault point, and R is the inductance value per unit length of the cable to be tested, and C is the capacitance value per unit length of the cable to be tested, both of which are parameters of the cable that can be found.

As shown in Figure 8, the cable fault location troubleshooting device also includes:

A low-voltage pulse signal generator 67, the low-voltage pulse signal generator 67 is electrically connected to the cable 62 to be tested through the first circuit 63, and is used to send a low-voltage pulse signal to the cable 62 to be tested;

The first line 63 is also provided with a signal generator switching switch 68;

The signal detection device 64 is also used to detect the low-impedance fault reflection pulse returned by the cable 62 to be tested;

The distance calculator 65 is also used to calculate the distance from the cable fault point to the cable according to the time interval between the low-resistance fault reflection pulse and the low-voltage pulse transmission signal and the propagation speed of the low-resistance fault reflection pulse. The distance of the fault location device.

The distance from the cable fault point to the cable fault location device and the propagation velocity of the low-impedance fault reflection pulse measured by the distance calculator 65 can be displayed on the waveform display, as shown in FIG. 10 .

Please refer to FIG. 8, the initial state of the signal generator switch 68 is connected with the low-voltage pulse signal generator 67;

The signal generator switching switch 68 is also used to switch to the high-voltage DC signal generator 61 if the signal detection device 64 does not detect the low-impedance fault reflection pulse;

The cable fault location and investigation device also includes a discriminator 69; the discriminator 69 is used to determine whether the cable under test 62 when a high-impedance fault occurs; the discriminator 69 is also used to determine that the cable 62 under test has no fault if the signal detection device 64 does not detect the high-impedance fault reflection pulse reflected by the cable 62 under test.

As shown in Figure 6, the cable fault location troubleshooting device also includes:

connected to the reverse diode 601 and the current limiting resistor 602 of the first line 63 in sequence from the high voltage direct current signal generator 61;

The shunt resistor 644 is connected between the DC blocking capacitor 641 and the sampling resistor 642 .

The reverse diode 601 has unidirectional conductivity to ensure that the current flows in the same direction. The current limiting resistor 602 is used to divide the voltage and shunt the current to limit the excessive current flowing through the first line 63. The shunt resistor is set in the DC blocking capacitor Between 641 and the sampling resistor 642 , the function of current limiting can be played to prevent the voltage of the sampling resistor 642 from being too large and affecting the waveform display 643 .

The method and system of the present invention are mainly used in the process of electric power maintenance. The cable fault situation and the buried environment are relatively complicated and varied. The test personnel should be familiar with the cable buried direction and environment, accurately determine the nature of the cable fault, and select a suitable instrument. Only by working with the measurement method and following certain procedures can the fault point of the cable be successfully measured.

On the basis of the original low-voltage pulse fault testing equipment, the device of the present invention places a high-voltage DC signal generator in parallel in the low-voltage pulse return signal generator, so that the two can be switched at will, so that for low-resistance, short-circuit, and open-circuit faults, low-voltage The pulse signal is used for positioning, and when a high-resistance fault is encountered, the low-voltage pulse signal source can be switched to a high-voltage DC signal source to test and locate the high-resistance fault.

The device has a good detection effect in the actual use process, and the error is less than 20cm. Figure 10 is the actual measurement of the short-circuit fault detected by switching to the low-voltage pulse signal:

Figure 11 is an actual measurement diagram of a high-impedance fault detected by switching to a high-voltage DC signal. The valley waveform at the vertical dotted line in the figure is the return waveform of a high-impedance fault.

Each embodiment in this specification is described in a progressive manner, the same and similar parts of each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments.

The embodiments of the present invention described above are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (6)

1. A cable fault location and investigation method is characterized in that, it is used for a cable fault location and investigation device, and the cable fault location and investigation device includes a high-voltage direct current signal generator connected to the cable to be tested and a high-voltage direct current signal generator connected to the cable to be tested Signal detection equipment; the cable fault location troubleshooting method includes: The high-voltage DC signal generator sends a high-voltage DC signal to the cable to be tested; Using the signal detection device to detect the high-impedance fault reflection pulse and detection time reflected by the cable to be tested; Calculate the distance from the cable high-resistance fault point to the cable fault location device according to the time interval between the high-resistance fault reflection pulse and the high-voltage direct current signal and the propagation speed of the high-resistance fault reflection pulse; The cable fault location and investigation device also includes a low-voltage pulse signal generator, and the cable fault location and inspection method also includes: The low-voltage pulse signal generator sends a low-voltage pulse transmission signal to the cable to be tested; Detecting the low-impedance fault reflection pulse returned by the cable to be tested; Calculate the distance from the cable fault point to the cable fault location device according to the time interval between the low-resistance fault reflection pulse and the low-voltage pulse transmission signal and the propagation speed of the low-resistance fault reflection pulse; Judging the polarity of the low-impedance fault reflection pulse returned by the cable to be tested; If the reflected pulse of the low-resistance fault is positive, it is determined that the cable fault is an open circuit fault; If the reflected pulse of the low-resistance fault is negative, it is determined that the cable fault is a short-circuit fault. 2. cable fault location investigation method according to claim 1, is characterized in that, also comprises: Obtaining in advance the distance between the cable terminal to be tested and the cable fault location and troubleshooting device; Using the low-voltage pulse signal generator to send a low-voltage pulse transmission signal to the cable under test; If the positive polarity pulse returned by the cable to be tested is detected; then calculate the distance between the positive polarity pulse generation point and the cable fault location device; If the difference between the distance between the cable terminal to be tested and the cable fault locating device and the distance between the positive polarity pulse generation point and the cable fault locating device is greater than or equal to a predetermined distance, then it is determined that the cable fault is an open circuit Fault. 3. cable fault location investigation method according to claim 1, is characterized in that, also comprises: Using the low-voltage pulse signal generator to send a low-voltage pulse transmission signal to the cable under test; If the low-impedance fault reflection pulse is not detected, switch to the high-voltage direct current signal generator, and use the high-voltage direct current signal generator to send a high-voltage direct current signal to the cable to be tested; If the high-impedance fault reflection pulse reflected by the cable under test is detected, it is determined that a high-impedance fault occurs in the cable under test; if the high-impedance fault reflection pulse reflected by the cable under test is not detected, then it is determined that the The test cable is faultless. 4. A cable fault location and troubleshooting device, characterized in that it comprises: A high-voltage direct current signal generator, the high-voltage direct current signal generator and the monitoring point of the cable to be tested are electrically connected through a first line, and are used to send a high-voltage direct current signal to the cable to be tested; A signal detection device, the signal detection device is connected to the first line through a second line, and is used to detect the high-impedance fault reflection pulse and detection time reflected by the cable to be tested; The signal detection device includes a DC blocking capacitor, a sampling resistor, and a waveform display connected in parallel with the sampling resistor in sequence from the connection point of the first line and the second line; the waveform display is used to detect and display The high-voltage direct current signal, the high-impedance fault reflection pulse, and the detection time respectively corresponding to the high-voltage direct current signal and the high-impedance fault reflection pulse; A distance calculator, connected to the signal detection device, used to calculate the time interval between the high-impedance fault reflection pulse and the high-voltage direct current signal according to the detection time corresponding to the high-voltage direct current signal and the high-impedance fault reflection pulse respectively ; Also used to calculate the distance between the cable high-resistance fault point and the cable positioning device according to the time interval between the high-resistance fault reflection pulse and the high-voltage direct current signal and the propagation speed of the high-resistance fault reflection pulse ; A low-voltage pulse signal generator, the low-voltage pulse signal generator is electrically connected to the cable under test through the first line, and is used to send a low-voltage pulse signal to the cable under test; The first line is also provided with a signal generator switching switch; The signal detection device is also used to detect the low-impedance fault reflection pulse returned by the cable to be tested; The distance calculator is also used to calculate the cable fault point to the cable fault location device according to the time interval between the low-resistance fault reflection pulse and the low-voltage pulse transmission signal and the propagation speed of the low-resistance fault reflection pulse the distance. 5. The cable fault location and investigation device according to claim 4, characterized in that, The initial state of the switchover switch of the signal generator is connected to the low-voltage pulse signal generator; The signal generator is also used to switch to the high-voltage direct current signal generator if the signal detection device does not detect the low-impedance fault reflection pulse; The cable fault location and troubleshooting device also includes a discriminator; the discriminator is used to determine that a high-impedance fault occurs in the cable to be tested if the signal detection device detects a high-impedance fault reflection pulse reflected by the cable to be tested; The discriminator is further configured to determine that the cable to be tested has no fault if the signal detection device does not detect the high-impedance fault reflection pulse reflected by the cable to be tested. 6. The cable fault location and troubleshooting device according to claim 4, further comprising: sequentially connected to the reverse diode and the current limiting resistor of the first line from the high voltage direct current signal generator; A shunt resistor connected between the DC blocking capacitor and the sampling resistor.