JP3653317B2 - High voltage overhead distribution line ground fault location system and measuring instrument - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ground fault fault locating system for locating a fault point of a ground fault occurring in a high-voltage overhead distribution line, and a measuring instrument used in the system.
[0002]
[Problems to be solved by the invention]
A high voltage is applied to a stopped (power failure) high-voltage overhead distribution line, and a traveling wave due to a discharge generated at the point of failure is installed and connected to a position on the opposite side from the point of failure of the stopped distribution line. In the high voltage overhead distribution line ground fault fault location system, which is received by the first measuring instrument and the second measuring instrument, and the fault location is determined based on the difference in reception time of the traveling wave by the two measuring instruments. When the above high voltage is applied, a charging current corresponding to the line condition such as the line constant flows in the healthy phase, and a traveling wave generated by the discharge at the failure point is superimposed and synthesized on the same charging current in the failure phase. Current flows.
[0003]
If the ground fault resistance at the failure point is high, the traveling wave flowing in the fault phase is limited to be small due to the influence of the ground fault resistance. Therefore, even if the measurer attempts to measure the rising point of the failure current phase due to the traveling wave of the synthesized current waveform, that is, the reception time of the traveling wave, it is difficult to determine the rising point, and the measurement error of the reception time is large. There was a first problem that it was easy to become.
[0004]
In addition, if a trigger occurs due to a traveling wave generated by a discharge at the failure point before the trigger trigger threshold is exceeded when the waveform is captured by the measuring instrument, the timing of waveform capture is shifted and the memory There was a second problem in that the waveform acquisition to the point failed, and the fault location operation had to be redone.
[0005]
Accordingly, an object of the invention of claim 1 is to provide a high-voltage distribution line ground fault fault location system that can eliminate the first problem.
The second aspect of the invention is to provide a measuring instrument used for the high-voltage distribution line ground fault fault location system according to the first aspect, which can solve the second problem.
[0006]
[Means for Solving the Problems]
In order to achieve the object, the invention of claim 1 includes a transmitter (2) connected to the stop distribution line (1) and applying a high voltage to the stop distribution line (1), and the stop distribution line ( 1) a first measuring device (7) and a second measuring device (13) respectively connected to the stop distribution line (1) at positions (A) and (B) separated from each other on the opposite side from the failure point (a). ), And the traveling wave (b) (b ') propagated from the failure point (b) by the discharge generated at the failure point (b) by the high voltage applied by the transmitter (2) is first measured. The distance between the measuring device (7) and the second measuring device (13), and the distance from the measuring device (7) (13) to the failure point is determined based on the difference in reception time between the measuring devices (7) and (13). In the high-voltage overhead distribution line ground fault location system
In the first measuring device (7) and the second measuring device (13), the waveforms of the healthy phase (S phase, T phase) and the fault phase (R phase) are taken and subtracted, respectively, and the subtracted waveforms are obtained. Based on the measurement time of the traveling wave (b) (b '),
The high voltage overhead distribution line ground fault fault location system is characterized in that the difference between the reception times of the two measuring devices (7) and (13) is obtained from the reception time thus measured.
[0007]
According to a second aspect of the present invention, there is provided a memory (22) having a predetermined number of addresses for sequentially overwriting and updating data obtained by sampling a waveform of each phase at a predetermined interval (50 ns), and the data has a predetermined threshold. A comparator (25) for generating a trigger signal when the value is exceeded,
From the time when the trigger signal is generated, the writing of data into the memory (22) is completed by writing to addresses smaller than the certain number, and
2. The high voltage overhead distribution line ground fault fault location system according to claim 1, wherein captured data before the trigger signal is generated and captured data after the trigger signal is generated are continuously displayed. It is a measuring instrument for use.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, reference numeral 1 is a three-phase stop high-voltage distribution line in which a fault has occurred and a fault relay section is separated by a protective relay device (not shown), and 2 is a high voltage applied to the stop high-voltage distribution line 1. A transmitter for application is inserted and connected between one end (the left end in the figure) A of the stop high-voltage distribution line 1 and the ground.
[0009]
The output terminals 20A, 20B, and 20C of the transmitter 2 are connected to the R phase, S phase, and T phase of the stop high-voltage distribution line via connection lines 3A, 3B, and 3C, respectively. 20D is a ground terminal. Reference numerals 4, 5, and 6 denote current transformers (hereinafter abbreviated as CT) connected to the connection lines 3A, 3B, and 3C, respectively, and detect currents flowing through the connection lines 3A, 3B, and 3C, respectively. Tell 7
[0010]
The other end (right end in the figure) B of the stop high-voltage distribution line 1 is a measuring capacitor 9 having a capacity of 0.1 μF in a three-phase collective state in which the R-phase, S-phase, and T-phase are respectively connected via connection lines 8A, 8B, and 8C. Is grounded through.
[0011]
Reference numerals 10, 11, and 12 denote current transformers (hereinafter abbreviated as CT) connected to the connection lines 8A, 8B, and 8C, respectively, and detect currents flowing through the connection lines 8A, 8B, and 8C to detect a second measuring instrument. Tell to 13.
[0012]
A is a ground fault point generated in the R phase, and consists of a series equivalent circuit of a gap G and a ground fault resistance R as shown in FIG. In the embodiment, the ground fault resistance R is 500Ω. The S phase and the T phase are healthy phases.
[0013]
As shown in FIG. 3, the transmitter 2 receives the high voltage generated by the DC power supply 14, the booster circuit 15 that is fed from the DC power supply 14 and generates a high voltage of 10 to several kV, the diode 16, and the booster circuit 15. Each phase of the stop high-voltage overhead distribution line 1 through the capacitor 17 that stores power, the matching resistor 18 that limits the inflow current from the transmitter 2 to the stop high-voltage overhead distribution line 1, and the high voltage stored in the capacitor 17 via the matching resistor 18 The switch 19 to be applied to, the output terminals 20A, 20B, 20C and the ground terminal 20D are connected.
[0014]
In the transmitter 2 of FIG. 3, when the switch 19 is temporarily closed, a high voltage pulse P having a width of the closed period τ is generated between the ground terminal 20D and the output terminals 20A to 20C. FIG. 4 shows the waveform of the high voltage pulse P generated in this manner, and FIG. 4A shows the case where a high voltage pulse of 10 kV is generated twice at an interval t. b) shows the case where a higher 15 kV high voltage pulse is generated at an interval t after the 10 kV high voltage pulse.
[0015]
FIG. 5 is a block diagram of the first measuring instrument 7 and the second measuring instrument 13. The measuring instruments 7 and 13 are different in CT connected as described in FIG. 1, and the configuration of the measuring instrument itself is as follows. Since the software has the same configuration, only the configuration of the first measuring instrument 7 will be described below.
[0016]
Reference numeral 21 denotes three A / D converters that sample the analog inputs from the CTs 4, 5, and 6 at regular intervals and convert them into digital values. Reference numeral 22 denotes a memory that stores data of the A / D converter 21. Three 8-bit memories from address 0 to address 262143 are provided for the R phase, S phase, and T phase.
[0017]
23 is a clock generator that generates a 20 MHz clock, 24 is a counter that counts the clocks from the clock generator 23 and returns to zero when it reaches 262143, and the value of the counter 24 increases by one for each cycle of the clock. If it counts up to 262143, it returns to 0 and counts up to 262143 again.
[0018]
The memory 22 associates the numerical value of the counter 24 with the address (address) of the memory 22 and takes in the waveform data from the A / D converter 21. When the counter 24 returns to 0, the address (address) of the memory 22 is obtained. ) Returns to 0 and is overwritten from the old data (see FIGS. 6A and 6B).
[0019]
The A / D converter 21 and the memory 22 are provided for the R, S, and T phases corresponding to CT4, 5, and 6 in total.
Reference numeral 25 denotes a comparator, and there are three comparators corresponding to the R, S, and T phases as in the case of the A / D converter 21, and a predetermined threshold value (trigger level) is set to the A / D converter 21. A trigger signal is generated when any one of the three-phase data is exceeded. The threshold value is set to a level that does not cause malfunction due to noise.
[0020]
26 receives the trigger signal of the comparator 25, starts counting the clock of the clock generator 23, and counts a numerical value from 0 to 261119.
Reference numeral 27 denotes a trigger address storage device for storing the numerical value of the counter 24 when the trigger signal is generated from the comparator 25, that is, the address (address).
[0021]
The memory 22 is related to take in the data for 261120 addresses (addresses) determined by the counter 26 from the address at the time when the trigger signal is output, and end the storage operation. 28 is a GPS receiver that receives a signal every 0.1 second from a GPS satellite, and resets the value of the counter 24 to 0 by this signal, thereby correcting the timing of capturing waveform data into the memory 22 by the clock. To do.
[0022]
That is, by doing this, the timing of waveform data fetching into the memory of the first measuring instrument 7 and the second measuring instrument 13 is synchronized, and the accuracy of fault location is improved.
[0023]
A method for synchronizing the operations of the time counters of both measuring devices with a reference time signal is well known in Japanese Patent Laid-Open No. 56-63274.
Next, 29 is a CPU, which displays the waveform of each phase on the display 30 based on the waveform data of each phase stored in the memory 22 and the trigger address stored in the trigger address memory, Performs operations such as locating the location of the failure point.
[0024]
Reference numeral 31 is a program memory for storing a calculation program of the CPU 29, 32 is an input device including a keyboard such as a numeric keypad for operating the measuring instrument 7, and 33 is a power source.
The display 30 can use a CRT like a digital oscilloscope, but in this embodiment, an EL display having an X axis (horizontal axis) of 640 dots and a Y axis (vertical axis) of 480 dots is used.
[0025]
In this embodiment, a clock of 20 MHz (period 50 ns) is used, and 50 ns corresponds to a traveling wave (surge) propagation distance of about 12.5 m. Therefore, the resolution of fault location is about 12.5 m.
[0026]
The amount of data fetched into the memory 22 is 262144 × 50 ns≈13 ms, and the synchronization with the GPS 0.1 second signal is 100 mS / 13 mS = 7.6, and the frequency is once every 7 to 8 times. Thus, the counter 24 is reset to 0 to synchronize both measuring instruments 7 and 13.
[0027]
Next, the operation of the above embodiment will be described.
As shown in FIG. 1, the transmitter 2, the first and second measuring devices 7, 13 and the like are connected to the stopped high-voltage overhead distribution line 1, and measurement for fault location is started. The measurement flow will be described with reference to FIG.
[0028]
First, in step 100, the measurer sets the voltage (range) of the transmitter 2.
Next, in step 101, the measurer turns on the switch 19 of the transmitter 2 to apply a high voltage to the R, S, and T phases of the stop distribution line 1.
[0029]
Next, in step 102, the waveforms of the R, S, and T phases are taken into the memory 22 as digital values. The sampling interval at this time is 50 ns of the clock cycle as described above, and the digital data is stored in order from address (address) 0 to address (address) 262143 in the memory 22, and the counter 24 counts to 262143. When it returns to 0, the address of the memory 22 also returns to 0 and overwriting is performed on the old data (as described above).
[0030]
When any of the three-phase data of the A / D converter 21 exceeds a certain threshold value (trigger level), a trigger signal is output from the comparator 25, and the numerical value (trigger address) of the counter 24 at that time is stored as the trigger address. Stored in the device 27. At the same time, the counter 26 starts counting from 0 and counts up to 261119.
[0031]
The memory 22 takes in data for 261120 addresses (addresses) by the counter 26 from the time (address) of the trigger signal, and finishes taking in.
These procedures and the zero reset of the counter 24 every 0.1 second by the GPS signal are apparent in FIG. FIG. 8 shows waveform data of the failure phase R of the measuring devices 7 and 13.
[0032]
The trigger signal is generated at the time when the switch 19 is turned on and the charging current flows through the stop distribution line.
Next, the R, S, and T3 phase waveform data captured in the memory 22 is displayed on the EL display to check whether the waveform has been successfully captured (step 104). The waveform is captured again by changing the voltage (range) of the machine and operating the switch 19 or the like.
[0033]
FIG. 9 shows the display waveforms of the R, S, and T phases when successful. In this case, it can be seen from the waveform in FIG. 9 that the two phases S and T are healthy phases and the R phase is a failure phase.
In this case, the data from the memory 22 is displayed in order from the data at the address (address) going back 1024 addresses (address) from the stored value (address) of the trigger address memory 27. Note that the display goes back from the rising point of the waveform (the position of the trigger signal in FIG. 5) because the distance between the measuring instrument and the failure point is close, and the discharge progresses even when a discharge traveling wave occurs at a relatively low voltage. This is because the waveforms before and after the rising of the wave can be accurately supplemented and displayed.
[0034]
If the waveform acquisition is successful, one of the three phases of the waveform of the first measuring instrument 7 shown in FIG. 5 is the R phase that is the fault phase, the S phase that is the healthy phase, and the T phase. On the other hand, for example, the S phase is selected, and the R phase and S phase of the selected phase are input through the input device 31 (step 105).
[0035]
The CPU 28 subtracts the waveform data of the two selected phases by the differential arithmetic expression in the program memory 30, and the previously selected two-phase (R phase and S phase) waveform and the subtracted differential waveform (R− S) is displayed on the display 30 as shown in FIG.
[0036]
The display 30 can display only 640 dots on the X axis (time axis). That is, only 640 pieces of data can be displayed. In order to display the 262144 address (address) data (the entire captured waveform) stored in the memory 22,
262144 ÷ 640 ≒ 410 address (address)
Every other data, that is, a part of all the imported data is thinned out,
400 addresses x 50 ns = 20 μs
Each data will be displayed.
[0037]
Therefore, the time difference between the displayed dots is as much as 20 μs, and 20 μs corresponds to a traveling distance of traveling wave of about 5000 m. A difference of 1 dot causes a large positioning error, and the positioning accuracy of the distance from the measuring instrument to the accident point is high. It is so bad that it is not practical.
[0038]
Therefore, the horizontal axis (X axis, time axis) is gradually enlarged, and the vicinity of the point where the traveling wave is generated by the discharge is enlarged and displayed up to detailed data (data for each address, that is, the time difference between dots is 50 ns). The distance from the vessel to the accident point is determined with high accuracy.
[0039]
The CPU 29 calculates the difference R−S between the digital data of the failure phase R and the healthy phase S and displays it on the display 30 for the following reason.
FIG. 12 is an enlarged view of the vicinity of the rising point of the R, S, and T3 phase waveforms in FIG. Point A is the rise of the waveform due to the charging current to the stop distribution line due to the application of a high voltage from the transmitter 2 to each phase. The waveform in region 1 before that is noise, and the S phase in region 2 after that. The waveform of the T phase, that is, the healthy phase is obtained by superimposing the waveform of the charging current on the noise.
[0040]
However, in the R phase of the fault phase, the waveform in the region 2 is different from the waveforms of the S phase and T phase of the healthy phase, and a small hump Q rising at the point B is superimposed. The small hump Q rising at the point B is obtained by picking up the traveling wave due to the discharge generated at the failure point a in the memory 22 of the first measuring instrument by CT4.
[0041]
FIG. 13 makes this point easier to see, and the circle D is a circle D surrounding a part of the R-phase waveform of FIG. 9. 12 and 13 exaggerate the hump Q in order to make it easy to see the rising point B caused by the traveling wave. Actually, as shown in these two figures, it is generated by the discharge at the failure point. It is difficult to clearly confirm the rising point B of the traveling wave from the waveform of the fault phase.
[0042]
Therefore, in the present invention, the CPU 30 calculates the difference (RS) between the waveform data of the failure phase and the healthy phase, thereby extracting only the traveling wave due to the discharge at the failure point A, and determining the rising point B of the traveling wave. It is easy to do.
[0043]
14 partially exaggerates the R-phase and S-phase waveforms shown in FIG. 12 and the difference R-S-phase differential waveform in a size corresponding to FIG. When the differential waveform shown as the phase is seen, the rising point B of the traveling wave can be clearly read.
[0044]
By the way, as described above, the differential waveform that is the difference between the waveform data of the R phase (failure phase) and the S phase (healthy phase) shown in FIG. The rising point B of the differential waveform shown in the R-S phase is the traveling wave due to the discharge at the failure point a obtained at one end A of the stop distribution line 1.
[0045]
A procedure for accurately reading the position of the rising point B by enlarging the horizontal axis in FIG.
In step 107, the time cursor is set to the surge (traveling wave) generation point, that is, the rising point B, and the address (address) of the rising point B where the cursor is set is input to the CPU 29.
[0046]
In step 108, the horizontal axis (time axis) is enlarged. When the keyboard of the input device 32 is operated to input OK, the waveform is enlarged and displayed.
The RS-phase differential waveform is enlarged for the first time, and the data for 40 points (80 in total) before and after the surge occurrence point, that is, the rising point B and the point designated by the cursor are displayed on the display 30. On a limited screen.
[0047]
In other words, as described above, the amount that changes every time one dot is shifted is about 400 addresses.
400 addresses x 80 (dots) / 640 = 50 addresses (addresses)
Every other data, that is, 50 addresses × 50 ns = 2500 ns = 2.5 μs
Each data is displayed on the screen of the display 30 (see FIG. 10B).
[0048]
In the second enlargement, the data for 32 points (64 in total) before and after the surge occurrence point and the point designated by the cursor are displayed on the limited screen of the display 30. That is, since the amount that changes every time one dot is shifted is 50 addresses,
50 addresses x 64 (dots) ÷ 640 ≒ 5 addresses (address)
Every other data, ie 5 addresses x 50 ns = 250 ns
Each data is displayed on the screen of the display 30 (not particularly shown).
[0049]
In the third enlargement, the data for 64 points (total 128) before and after the surge occurrence point and the point designated by the cursor are displayed on a limited screen of the display 30.
That is, since the amount of change for each dot is 5 addresses,
5 addresses x 128 (dots) / 640 = 1 address (address)
Each data is displayed on the screen of the display 30 (see FIG. 10C).
[0050]
As described above, the reason why the time axis of the differential waveform of the RS phase is gradually expanded is that there is a lot of missing data between dots, so the surge occurrence point specified by the cursor is the true surge occurrence. If there is a deviation from the point, if the time axis is expanded at once, there is a possibility that the point of occurrence of the surge will be off the screen and lose its sight, so this is done in stages in order to prevent it.
[0051]
In step 109, it is confirmed that the differential waveform of the RS phase has been maximized, and the process proceeds to the next step.
The procedure for expanding the time axis is the same as the time axis expanding operation in a known digital oscilloscope.
[0052]
In each of the above steps, the operation procedure of the first measuring instrument 7 has been mainly described. However, the same procedure is applied to the second measuring instrument 13 as shown in FIGS. 10 (a), 10 (b), and 10 (c). The corresponding waveforms in FIGS. 11A, 11B, and 11C are obtained, and the process proceeds to the next step.
[0053]
Next, in step 110, the time axis cursor is set to the point B in FIG. 10C, that is, the rising point of the traveling wave, which is the display of the first measuring instrument 7, and the keyboard of the input device 32 of the measuring instrument 7 is moved. When the operation is input and OK is input, the display 30 displays the address (address) from the 0 address (address) which is the reference point. Similarly, the time axis cursor of the second measuring device 13 is set to the point B ′ on the display screen, and the measuring device determines from which address (address) the B ′ point is from the 0 address (address) which is the reference point. It is displayed on 13 indicators. The traveling wave rising points B and B ′ points (addresses) displayed on the first measuring instrument 7 and the second measuring instrument 13 in this way are the traveling waves generated by the discharge at the fault point a. This corresponds to the time when the first and second measuring devices 7 and 13 are reached.
[0054]
Therefore, in step 111, the first measuring device 7 and the second measuring device 13 inquire about the addresses of the rising point B and the point B ′ and input the addresses, and in step 112, calculate the distance to the failure point. And display.
[0055]
That is, the address of the point B obtained by the first measuring device 7 is input to the second measuring device 13, and the address of the point B ′ obtained by the second measuring device 13 is input to the first measuring device 7. These addresses are input by operating the keyboard of the input device 32 of each measuring instrument 7 and 13.
[0056]
In the first measuring instrument 7, from the address of the point B where the traveling wave b has reached one end of the high voltage distribution line 1 and the address of the point B ′ where the traveling wave b ′ has reached the other end of the high voltage distribution line 1, The arrival time of traveling wave b is (address of point B) × (clock period 50 ns) ...... 1
The traveling time of the traveling wave b ′ is (B ′ point address) × (clock period 50 ns) 2
Is required.
[0057]
Therefore, the difference between the arrival time of the expression (1) and the arrival time of the expression (2) is the traveling wave arrival time difference, and the distance X to the failure point is determined by using the distance between the measuring instruments 7 and 13 and the traveling wave propagation velocity. It can be obtained by the following equation (3).
[0058]
X = {(distance between measuring instruments) − (traveling wave arrival time difference) × (propagation speed)} / 2 = 2
When the failure point A is close to each measuring instrument (traveling wave arrival time difference)> 0
If it is far from each measuring device (traveling wave arrival time difference) <0
It is.
[0059]
The propagation speed of the traveling wave is determined as follows: the traveling time of the traveling wave that reaches the other measuring device from one measuring device through the stopped high-voltage distribution line 1 and the distance between the two measuring devices when the connection of the measuring device or the like is completed. Is measured in advance, and the propagation speed of the traveling wave is obtained.
[0060]
【The invention's effect】
In the invention of claim 1, since the subtraction of the waveform between the failure phase and the healthy phase and taking out only the traveling wave to measure the traveling wave reception time, no skill is required, and even when a field worker measures it. The fault location can be accurately determined.
[0061]
According to the second aspect of the present invention, since the waveform before the traveling wave is generated and stored in the memory is stored and continuously displayed together with the waveform after the traveling wave is generated, the distance between the measuring instrument and the failure point is short. Even when a traveling wave due to discharge is generated at a relatively low voltage, the waveforms before and after the rising point of the traveling wave can be captured and displayed, and there is an advantage that waveform capturing errors are reduced.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing electrical connections in an embodiment of the present invention.
FIG. 2 is an equivalent circuit of a ground fault point in the embodiment of FIG.
FIG. 3 is an electric circuit diagram of a transmitter used in the embodiment of FIG. 1;
FIGS. 4A and 4B are diagrams showing different modes of the high voltage output pulse waveform of the transmitter of FIG.
FIG. 5 is a block diagram of a measuring instrument used in the embodiment of FIG.
6A and 6B are diagrams for explaining the memory of the measuring device in FIG. 5, in which FIG. 6A shows a ring counter-like configuration, and FIG. 6B shows an array of 8-bit memory for each address.
FIG. 7 is a flowchart illustrating the operation of the embodiment of the present invention.
FIG. 8 is a diagram for explaining a relationship between a failure phase waveform and a memory address when the waveform is taken into a memory according to an embodiment of the present invention;
FIG. 9 is a diagram showing a current waveform of each phase when a high voltage is applied to the stop distribution line in the embodiment of the present invention.
FIG. 10 is a diagram illustrating current waveforms of a fault phase (R phase) and a healthy phase (S phase) and waveforms of both phases (R phase and S phase) when a high voltage is applied to a stopped distribution line in the embodiment of the present invention. The figure which shows the signal which received the waveform of the difference of 1 with the 1st measuring device, (a) is the whole figure of a waveform, (b) is a figure which expands and shows the time axis, (c) is more It is the figure which expanded the time axis greatly.
FIG. 11 shows a current waveform of a fault phase (R phase) and a healthy phase (S phase) and a waveform of both phases (R phase and S phase) when a high voltage is applied to the stop distribution line in the embodiment of the present invention. The figure which shows the signal which the waveform of the difference of (2) received with the 2nd measuring device, (a) is the whole figure of a waveform, (b) is the figure which expands and shows the time axis, (c) is more It is the figure which expanded the time axis greatly.
12 is an enlarged view of the beginning of the waveform diagram of FIG. 9;
13 is an enlarged exaggerated view of a part of the failure phase (R phase) waveform of FIG. 9;
14 shows the failure phase (R phase) and the healthy phase (S phase) as they are in the waveform diagram of FIG. 9, and further, the R-S phase differential waveform obtained by subtracting the S phase waveform from the R phase waveform. FIG.
[Explanation of symbols]
1 Stop distribution line 2 Transmitter 7, 13 Measuring instrument 22 Memory 25 Comparator A Failure point B, B 'Traveling wave (surge)
A, B Position R phase Fault phase S phase, T phase Healthy phase

Claims (2)

The transmitter (2) connected to the stop distribution line (1) and applying a high voltage to the stop distribution line (1) and away from the failure point (b) of the stop distribution line (1) The first measuring device (7) and the second measuring device (13) respectively connected to the stop distribution line (1) at the positions (A) and (B) were applied by the transmitter (2). The first measuring device (7) and the second measuring device (13) receive the traveling wave (b) (b ') propagating from the failure point (b) due to the discharge generated at the failure point (b). In the high-voltage overhead distribution line ground fault fault location system that determines the distance from the measurement instrument (7) (13) to the fault point based on the difference in reception time between the two measuring instruments (7) and (13),
In the first measuring device (7) and the second measuring device (13), the waveforms of the healthy phase (S phase, T phase) and the fault phase (R phase) are taken and subtracted, respectively, and the subtracted waveforms are obtained. Based on the measurement time of the traveling wave (b) (b '),
A high-voltage overhead distribution line ground fault fault location system characterized in that a difference in reception time between the two measuring devices (7) and (13) is obtained from the reception time thus measured. A memory (22) consisting of a fixed number of addresses for sequentially overwriting and updating data sampled at a fixed interval (50 ns) of the waveform of each phase, and generating a trigger signal when the data exceeds a predetermined threshold A comparator (25)
From the time when the trigger signal is generated, the writing of data into the memory (22) is completed by writing to addresses smaller than the certain number, and
2. The high voltage overhead distribution line ground fault fault location system according to claim 1, wherein the captured data before the trigger signal is generated and the captured data after the trigger signal is generated are continuously displayed. Measuring instrument for use.

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