JPH065252B2 - Accident location method for cable tracks - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a fault location method for a cable line, and in particular,
The present invention relates to an accident point locating method for cable lines that can locate accident points with high accuracy.

[Technical Background of the Invention] Conventionally, as shown in FIG. 5 as a fault location method of a cable line, a high voltage is applied from a high voltage source DCG to the cable line in the fault phase to cause a discharge at a fault point A. The pulse is detected as the first propagating signal S1 by the capacitor C and the impedance Z at the measuring end of the cable line, and the discharge pulse is reflected at the measuring end and negatively reflected at the fault point of the cable line. Then, a method is known in which the second propagation signal S2 is detected again at the measurement end, and the oscillogram is located on the synchroscope M. A typical example of the oscillogram at this time is shown in FIG. 6. The first propagation signal S1 is a pulse directly propagated from the accident point A to the measurement end, and the second propagation signal S2 is a discharge pulse reflected at the measurement end. It shows a pulse that is negatively reflected at the fault point A of the cable line, becomes a pulse of opposite polarity, and propagates again to the measurement end. Therefore, the time difference t between the first propagation signal S1 and the second propagation signal S2 at the measuring end. Is the time during which the pulse propagates back and forth between the accident point A and the measuring point, and the distance X from the measuring point to the accident point A is obtained from the pulse propagation velocity V by the following equation.

X = Vt. / 2 [Problems of background art] In such an accident point locating method, when the line includes the connection portion J, the first propagation signal S1 and the second propagation signal S2 are included.
The reflected wave S2 'from the connection part enters between the time intervals T and T. ′
There is a problem that the position of the accident point A cannot be located due to the erroneous measurement.

In addition, since the lead wire system at the measuring end of the accident phase, the lead wire system at the connection of the far end of the accident phase and the sound phase, and the lead wire system at the measuring end of the sound phase act strictly as a delay element of the pulse, However, there is a problem that it becomes a measurement error factor.

[Object of the Invention] The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a method for locating an accident point of a cable line capable of locating an accident point with high accuracy.

[Summary of the Invention] In order to achieve such an object, according to the fault location method of a cable line of the present invention, a calibration pulse is applied to the measurement end of the cable line in the fault phase, and the detection is performed at the measurement end. Calculating a time difference t1 between the one propagation signal and the second propagation signal in which the calibration pulse is transmitted from the distant end of the cable line to the measuring end through the cable line of a healthy phase and detected at the measuring end, A calibration pulse is applied to the far end of the cable line in the accident phase, and the first propagation signal detected at the measurement end and the calibration pulse are applied from the far end of the cable line to the measurement end via the cable line in the sound phase. A time difference t2 from the second propagation signal transmitted and detected at the measurement end is calculated, and a high voltage is applied to the cable line in the accident phase, and a discharge pulse generated at the accident point is detected at the measurement end. The biography of The time difference t between the seed signal and the second propagation signal which is transmitted from the distant end of the cable line to the measuring end via the cable line of the sound phase and is detected at the measuring end is calculated, and the measurement is performed. Locating the fault point of the cable line by determining the distance x from the end to the fault point from x = (t1-t) L1 / (t1-t2) (where L1 is the cable line length of the fault phase) Is.

Embodiments of the Invention Preferred embodiments of the present invention will be described below with reference to the drawings.

The fault location method of the cable line of the present invention is realized by the system configuration shown in FIG. That is, in the figure, the measurement end of the cable line 2 in the accident phase is connected to the high voltage source DCG, and is also grounded via the coupling capacitor C and the detection impedance Z. The capacitor C and the detection impedance Z detect the discharge pulse generated at the accident point (for example, A) of the cable line as the first propagation signal S1. An intermediate point between the capacitor C and the impedance Z is connected to the channel CH1 of the digital memory 4 by the lead wire system 3 at the measurement end of the accident phase. It is assumed that the lead wire system 3 has a delay element 5 having a delay time T1. On the other hand, the far end of the cable line 2 is grounded via a capacitor C and an impedance Z, and
The middle point between the impedance Z and the impedance Z
Is connected to the far end of the lead wire system 7. The capacitor C and the impedance Z prevent the high voltage applied to the fault phase from being applied to the sound phase, and allow the discharge pulse generated at the fault point A of the cable line to pass to the sound phase. It is assumed that the lead wire system 7 has a delay element 8 having a delay time T2. The measuring end of the sound phase cable line 6 is grounded via the capacitor C and the impedance Z, and the intermediate point between the capacitor C and the impedance Z is connected to the digital memory 4 by the lead wire system 9 at the measuring end of the sound phase.
Channel CH2. It is assumed that the lead wire system 9 has a delay element 10 having a delay time T3. The capacitor C and the impedance Z generate the discharge pulse generated at the accident point A of the cable line 2
Is transmitted from the distant end to the measuring end via the cable line 6 of the sound phase and is detected as the second propagation signal S2 at the measuring end. The output end of the digital memory 4 is the standardizer 1
Connected to 1. The channels CH1 and CH2 of the digital memory 4 are both the first propagation signal S.
Triggered by 1.

In such a system configuration, the fault location of the cable line according to the present invention is performed by the following procedure.

The calibration pulse is applied to the measurement end of the cable line 2 in the accident phase, propagates through the cable line 2, and is distant at the measurement end. The second propagation signal S2 transmitted to the measuring end via the cable line 6 and detected at the measuring end is taken into the digital memory 4, its time t1 is calculated, and this data is transferred to the locator 11. This time difference t1 is t1 = T3 + T2-T1 + (L1 + L2) / V ... (1) (FIG. 2 (A)). Where L1 and L2 are the accident phase,
The length of the cable line in the sound phase, V indicates the propagation velocity of the pulse.

A calibration pulse is applied to the far end of the cable line 2 in the accident phase, propagates through the cable line 2, and is detected at the measurement end.
Second propagation signal transmitted from the distant end of the cable to the measuring end through the cable line 6 having a sound phase and detected at the measuring end
S2 and S2 are loaded into the digital memory 4, the time difference t2 between them is calculated, and this data is transferred to the locator 11. This time difference
t2 is t2 = T3 + T2-T1 + (L2-L1) / V ... (2) (Fig. 2 (b)).

From the equations (1) and (2), the propagation velocity V can be obtained by V = 2L1 / (t1-t2) ... (3).

A high voltage is applied to the accident cable line 2 from the high voltage source DCG. It is assumed that the discharge pulse occurs at accident point A, for example. The discharge pulse propagates through the cable line 2 and is detected at the measurement end, and the first propagation signal S1 and the discharge pulse are transmitted from the distant end of the cable line 2 to the measurement end via the cable line 6 in the normal phase. Then, the second propagation signal S2 detected at the measuring end is loaded into the digital memory 4, the time difference t thereof is calculated, and this data is transferred to the locator 11. This time difference t is t = T3 + T2-T1 + (L2 + L1-2X) / V = T3 + T2-T1 + ((L2-L1) +2 (L1-X)) / V In addition, (2), (3 Substituting the equation), t = t2 + 2 (L1-X) / V = t2 + (L1-X) (t1-t2) / L1 (FIG. 2 (C)).

Therefore, the distance x from the measurement end to the accident point can be obtained as x = (t1-t) L1 / (t1-t2), the position is calculated by the locator 11, and the calculation result is obtained by the attached printer. You can also launch it. In this way, the cable line length L of the known accident phase
1, the distance x is calculated only from the measurable values t1, t2, t,
The fault point of the cable line is accurately located without being affected by the delay times T1, T2, T3 of the delay elements 5, 8, 10.

Further, since the sound phase is used when transmitting the discharge pulse going far from the accident point to the measurement end, even if the line normally includes the junction box portion NJ (Fig. 3 (a)), The time t of the first propagation signal S1 and the second propagation signal S2 (the third
The figure (b)) is accurately measured, and the position of the accident point A can be located without being affected by the reflected wave S2 'from the ordinary junction box portion NJ.

In addition, as shown in FIG.
When grounded by the cross bond method by J, the discharge pulse from the accident point to the healthy phase is induced in the insulation junction box from the accident phase to the healthy phase. Before reaching the measurement end, the discharge pulse running in the accident phase enters from the cross bond point and the time difference t
(Fig. 4 (b)) becomes unclear, and it becomes impossible to locate the accident point. In this case, the delay time t2 of the delay element 8 may be positively used. That is, the delay time T2 of the delay element 8
Is larger than the time for the propagating wave of the discharge pulse to be induced from the accident phase to the sound phase. Therefore, after the induction from the accident phase to the sound phase is completely eliminated, the discharge pulse from the accident point to the far end can be transmitted to the measurement end through the sound phase, and the time difference t
Can be accurately determined, and the location of the accident point can be located.

[Effects of the Invention] As is clear from the above embodiments, according to the fault location method of the cable line of the present invention, the cable of the sound phase when transmitting the discharge pulse from the fault point to the far end to the measurement end When a calibration pulse is applied to the measurement end of the cable line in the accident phase, a calibration pulse is also applied to the far end, and a high voltage is applied to the cable line in the accident phase, a discharge pulse is applied at the accident point. The first propagation signal and the pulse, which are respectively detected at the measurement end, are transmitted from the far end of the cable line to the measurement end through the cable line of the sound phase and are detected at the measurement end. Since the time difference from the second propagation signal is calculated and the distance from the measurement end to the fault point is calculated, it is not affected by the delay time of the delay element, and it is affected by the reflection at the connection part of the cable line. The accident point of the cable line is accurately located without being damaged.

[Brief description of drawings]

FIG. 1 is a system configuration diagram for realizing a coil fault point locating method for a cable line according to the present invention, FIG. 2 (a),
(B) and (c) are waveform diagrams of the discharge pulse propagation signal obtained by the same orientation method, and FIGS. 3 (a) and 3 (b) are line system configuration diagrams using a normal junction box to which the same orientation method can be applied, respectively. Waveform diagram of discharge pulse propagation signal, FIG. 4 (a),
(B) is a line system configuration diagram with an insulated junction box to which the same orientation method can be applied and a waveform diagram of its discharge pulse propagation signal, and FIGS. 5 and 6 are system configuration diagrams used in the conventional fault location method. FIG. 3 is a waveform diagram of a discharge pulse propagation signal thereof and FIG. 2 ... Accident phase cable line S1 ... First propagation signal 6 ... Healthy phase cable line S2 ... Second propagation signal t1, t2, t ... Time difference A ... Accident point x ... Distance

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuaki Namba 2-1-1, Oda Sakae, Kawasaki-ku, Kawasaki-shi, Kanagawa (Showa Electric Wire & Cable Co., Ltd.) (56) Reference JP-A-56-16878 (JP, A) JP-A-60-100061 (JP, A) JP-B-46-35465 (JP, B1)

Claims (1)

[Claims] 1. A first propagation signal detected at the measuring end by applying a calibration pulse to the measuring end of the cable line in the accident phase and the calibration pulse from the far end of the cable line through the cable line in the healthy phase. The time difference (t1) from the second propagation signal transmitted to the measurement end and detected at the measurement end is calculated, and a calibration pulse is applied to the far end of the cable line in the fault phase to be detected at the measurement end. A time difference (t2) between the first propagating signal and the second propagating signal which is transmitted from the far end of the cable line to the measuring end through the cable line of a healthy phase and is detected at the measuring end is calculated. Calculate,
The first propagation signal in which the discharge pulse generated at the accident point by applying a high voltage to the cable line in the accident phase is detected at the measurement end and the discharge pulse from the far end of the cable line through the cable line in the healthy phase Then, the time difference (t) from the second propagation signal transmitted to the measuring end and detected at the measuring end is calculated, and the distance x from the measuring end to the fault point is calculated as x = (t1-t) L1 / (T1-t2) (where L1 is the cable line length of the accident phase), and the fault point locating method of the cable line is characterized by locating the fault point of the cable line.