JPH0682512A - Fault locator for cable - Google Patents

Abstract

PURPOSE:To locate fault highly accurately by previously determining an apparent propagation delay time of surge caused by passage through a singular point such as a cross bond thereby correcting the surge detection time of magnetic field sensor. CONSTITUTION:Surge occurring upon fault of a cable is detected through at least two magnetic field sensors arranged at an appropriate interval along the cable and then the fault is located based on the difference between detection times. In this case, apparent propagation time of surge is delayed due to attenuation of the surge at a singular point, e.g. a cross bond, on the cable route. The propagation delay time of surge is previously measured by injecting a surge simulation waveform into a simulation circuit in order to correct surge detection time of the magnetic field sensor. An impulse voltage is applied on the simulation line system in order to simulate a point Q, separated by a predetermined distance from a cross bond IJ1, as a fault point. No fault is present in the section between the magnetic field sensors S1, S2 and this section is recognized as a sound section, thereby.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for locating an accident point on a cable, and more particularly to a cable accident point locating device for improving the locating accuracy.

[0002]

2. Description of the Related Art As a conventional technique of this kind, for example, in "Cable Accident Locator" of Japanese Patent Laid-Open No. 63-292076, a plurality of optical magnetic fields provided near a cable line for a surge caused by a ground fault or the like. It is disclosed that an optical signal detected by a sensor and output from each optical magnetic field sensor is transmitted to a transmission terminal device via an optical cable, and the transmission terminal device locates an accident point from the reception timing of each optical signal. Has been done.

Further, in "Fault point locating device for power transmission line" disclosed in Japanese Patent Laid-Open No. 4-54470, pulse signals are adjacent to each other in response to detection of a surge pulse in each slave station installed at three points of the power transmission line. Transmitted to the slave station, in the slave station receiving the pulse signal, the time difference between the pulse signal detected in the slave station and the received pulse signal is detected, the time difference is transmitted to the master station, and in the master station, The sound section and the failure section are determined by examining the time difference data, the propagation speed of the surge pulse is known from the time difference data of the sound section, and the failure point in the failure section is located from this speed.

[0004]

However, in the above-described orientation device, when the cable line has a singular point such as a cross bond, the surge current waveform after passing through the singular point becomes large as shown in FIG. Due to the attenuation, the detection time of the surge current was deviated, and as a result, the surge propagation time of the waveform was apparently delayed, resulting in a large error in the estimated value of the accident point. The present invention has been made to solve the above-mentioned problems, and provides an apparatus capable of accurately locating an accident point by correcting a propagation time delay of a surge pulse generated when passing through a cross bond. With the goal.

[0005]

According to the present invention, at least two magnetic field sensors mounted along a cable at appropriate intervals detect a surge generated at the time of a cable accident, and the fault point is located from the detection time difference. In the accident point locating device, the apparent surge propagation time delay, which is caused by the attenuation due to the passage of a singular point in the cable route such as a cross bond installed in the middle of the cable, is obtained in advance, and the detection time of the magnetic field sensor is set to the above. It is characterized in that it is corrected with the surge propagation time delay of.

[0006]

When the apparent surge propagation time delay shown in FIG. 1 is Δt and the surge propagation speed is v, the measurement result of the cable lengthened by Δt · v can be obtained. The delay Δt of the surge propagation time changes slightly depending on the size of the surge waveform before passing through the cross bond, but the surge simulation waveform is injected into the simulated line or the actual line in advance to measure Δt, and the magnetic field sensor is used. By subtracting this value Δt from the surge detection time, the accident point can be accurately located.

[0007]

FIG. 2 is a system diagram showing an embodiment of the apparatus of the present invention. The cable used as a simulated track is 77
KV, CV, 600 mm ² , total length 312.4 m, there is a cross bond IJ _{1 at a} distance L ₁ (132 m) from the left end of the cable, and a distance L ₂ (180 mm) from this cross bond IJ ₁ to the right end of the cable. Cross bond IJ2 also exists in the section of 0.4 m. S ₁ and S ₂ are the magnetic field sensor installed in the cable left and right edges of the cable head CH ₁ and CH _2, S ₂ is a magnetic field sensor installed in cross bond IJ _1. H ₁ , H ₂ , and H ₃ are electro-optical converters that convert the detection signals from the magnetic field sensors S ₁ , S ₂ , and S ₃ into optical signals, and output of the electro-optical converter H ₃ (pulses). )
Is supplied to the counter C-2 in the previous stage by optical fiber,
The output (pulse) of the electro-optical converter H ₂ is supplied to the counter C-1 at the preceding stage by an optical fiber. Counter C-2
Starts counting by pulse input from the electro-optical converter H _2, and stops counting by pulse input from the electro-optical converter H ₃ . The counter C-1 starts counting when a pulse is input from the electro-optical converter H ₁ and stops counting when a pulse is input from the electro-optical converter H ₂ . The transmission device LS2 transmits the count value of the counter C-2 to the transmission device LS1 by an optical fiber, and the transmission device LS1 transmits the count value of the counter C-1 and the count value of the transmission device LS2 to the optical fiber. It is transmitted to the master station which locates the accident point.

In the above system, the cross bond I
Impulse voltage of 17 KV was applied to simulate Q at 81.4 m point in the right direction from J ₁ as an accident point. In this simulation line, the S ₁ -S ₂ in the interval accident is not healthy section. The surge passage time t ₁₂ in this sound section is calculated by the following equation. t ₁₂ = KC ₁ −t ₀₁ (1) Here, K is a time interval per count of the counter C-1, C ₁ is a count value of the counter C-1, and t
₀₁ is a counter C- of the transmission device LS ₂ to the transmission device LS ₁ .
1 is a transmission time of an optical fiber for transmitting a signal for stopping 1). From the equation (1), the propagation velocity v of the surge is obtained by v = L ₁ / t ₁₂ (2). Next, the distance x from the cross bond IJ ₁ to the accident point Q is obtained by x = (L ₂ −v · t ₂₃ ) / 2 (3). Here, t ₂₃ is a surge passage time difference between the sensors S ₂ and S _3, and is given by t ₂₃ = KC ₂ −t ₀₂ (4). Next, in order to simulate P at the position of 99.6 m to the right of the cross bond IJ ₁ as an accident point,
The same procedure as above was performed by applying an impulse voltage of KV, and the experimental results are shown in the following table.

[0009]

[Table 1] Accident point t ₁₂ t ₂₃ Result of formula (3) Error P (109.6m) -0.8539μs -0.3489μs 117.1m + 7.5m Q (81.4m) -0.8539μs -0.0473μs 93.9m + 12.5m

From the above table, the accident point position x can be almost known, and the number of crossing points of the cross bond points can be known. On the other hand, in this simulated line, the delay Δt of the surge passage time at the cross bond point was 0.077 μsec on average from the separately measured result. Therefore, the following table was obtained by subtracting this Δt from t ₂₃ in Table 1 and using this as t ′ ₂₃ to obtain x.

[0011]

[Table 2] Accident point t ₁₂ t ₂₃ Result of formula (3) Error P (109.6m) -0.8539μs -0.1949μs 105.3m -4.3m Q (81.4m) -0.8539μs + 0.1067μs 81.9m + 0.5m

It was confirmed that the orientation error in Table 2 was smaller than that in Table 1.

[0013]

As described above, according to the present invention, an apparent surge propagation time delay caused by attenuation caused by passage of a singular point in a cable route such as a cross bond is obtained in advance, and the time detected by the magnetic field sensor is detected. Since it is corrected by the surge propagation time delay, it is possible to locate the accident point with high accuracy.

[Brief description of drawings]

FIG. 1 is a diagram showing a surge change after passing through a cross bond.

FIG. 2 is a system diagram showing an embodiment of the present invention.

[Explanation of symbols]

 S Magnetic field sensor H Electro-optical converter C Counter LS Transmission device IJ Cross bond

Claims (1)

[Claims] 1. A surge generated when a cable accident occurs,
In a fault point locator that detects at least two magnetic field sensors installed at appropriate intervals along the cable and locates the fault point from the detection time difference, a singular point in the cable route such as a cross bond installed in the middle of the cable A cable fault point locating device, characterized in that an apparent surge propagation time delay caused by attenuation due to passage is obtained in advance, and the detection time of the magnetic field sensor is corrected by the surge propagation time delay.