JPH04145379A - Accident point orientating method for power cable - Google Patents

Abstract

PURPOSE:To enhance the accuracy in the orientation of an accident point by installing surge-current detecting sensors and time counters, and by calculating and displaying the counted values in a central processing unit, while ignoring the influence of transmission time lag produced in a synchronous circuit. CONSTITUTION:On both terminals 1a, 1b of a power cable 1, surge current detecting sensors 2a, 2b such as optical CTs, and pulse generators 4a, 4b for sending the detected surge currents to time counters C15a, C25b as optical pulses are installed respectively. The pulse generator 4a detects a surge current 3 by means of an optical CT 2a, and at the same time sends an optical CT to the time counter C15a of self station, and also sends an optical pulse even to the time counter C25b of the neighboring station. The counted value is, directly or via a transmission terminal LS6, transmitted to a central processing unit MS7, and therein calculation and display are carried out.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is a POF cable (pipe type OF cable)
The present invention relates to a fault point locating method for power cable lines in which conductor surge currents can only be detected at both terminals.

(Prior Art and Problems to Be Solved) In the conventional technology for locating fault points in power cables, the location was determined only from the difference in the arrival time of surge pulse currents to both ends of the cable.

FIG. 2 is a block diagram of a conventional accident point locating method. As shown in the drawing, both terminal ends (Ia) of the power cable (1) (
Time counters C, (lla) and C2 (llb) each operated by a synchronous circuit (10) are installed at Ib), and the surge current (3) proceeding from the fault point (A) is
A surge current detection sensor (2) such as an optical CT installed on both ends (Ia, Nb) of the cable (1) detects it, and a pulse generator (4) converts it into a light pulse.
Ct (Ilg) and C2 (llb) are sent, and the surge signal causes the clock counter C1 (mouth a)'i
) to stop.

If we assume that the time when the accident occurred is 0, the display 'a'
Each time counter C displayed in (12a) and (12b)
1 (l1m), C2 (Ilb) four sound time t3, C2
is c1 → tr= ta ”' (1) C2 → t
2:tb-to...(2). here to
is the time delay of the synchronous line.

On the other hand, since the time (T) for propagation through the entire cable line length (L) is T = ta + tb - (3), tb = = T - ta ... (4), tl - C2 = ta I (T - ta)-tol=
2ta (T to) −(
5) Therefore, ta:=”-2 ÷ L-Yu-kyo...
(6) is found. If the propagation speed of surge current is V, then
The distance L3 is La=V-ta=vnyo'P'2! J-, , , can be obtained using (7). Here, N jls C2 are both measured values of the time counters Ct (lla) and C2 (llb) at the time of the accident, but vlTlto needs to be actually measured in advance.

However, since to usually uses a general communication line such as a telephone line, it is difficult to obtain a stable value, and there are problems in that there are many errors in measurement.

(Means for Solving the Problems) The present invention provides a fault point locating method for power cables that solves the above-mentioned problems. A timing counter that is driven and stopped based on the sensor information is installed, and information from the surge current detection sensor is sent to the timing counters of the own station and adjacent stations, and each count value is transmitted to the central processing unit for calculation and display. There is a particular thing.

(Example) FIG. 1 is a block diagram of a specific example of the method for locating fault points of power cables according to the present invention.

As shown in the drawing, both ends (l) of the power cable (1)
a) (Ib), respectively, a surge current detection sensor (2aH2b) such as an optical CT, and a pulse generator (48) that sends the detected surge current as an optical pulse to the time counter C+ (5a) and C2 (5b). 4b), time counters Cr (5a), C, (5b) which are driven and stopped by the above pulse signals.
). Then, the pulse generator of the own station and the time counter of the adjacent station are connected with optical fiber cables (8a) (8b), and the count value of the time counter is roughly calculated by the central processing a.
A transmission terminal 1.5 (6) for transmitting data to 5 (7) is installed at t and connected with an optical fiber cable (9).

(Function) One of the pulse generators (4B) detects the surge current (3) with the optical CT (2a) and at the same time detects the timing counter C of its own station.
, (5a). At the same time, the optical fiber cable (8a) sends two optical pulses to the clock counter C2 (5b) of the adjacent station.
Similarly, the other pulse generator (4b) sends optical pulses to
) detects the surge current (3) with an optical CT (2h), and at the same time sends an optical pulse to its own time counter Cs+ (5b), and also sends a light pulse to the other time counter C+ (5a) via an optical fiber cable (8b). It also sends light pulses.

And each time counter C+ (5a), C2 (sb) is
It is driven by the faster optical pulse from the own station or the neighboring station,
Stop later. Then, the count value (time) is sent directly or via the transmission terminal LS (li) to the central processing i.
It is transmitted to the It MS (7), where it is calculated and displayed.

At this time, the count value has positive polarity (+) when driven by the optical pulse of the own station, and negative polarity (-) when driven by the optical pulse of the adjacent station.

Therefore, the count value t0, C2 of each time counter C+ (5a), C2 (sb) is j, = tb+ to-ta (8) j2=
ta tent. -tb - (9) Similar to equation 6 (5), 1. 12, tl C2= 2
(tb ta)=2 (T-2ta)
-(to) is obtained. If the propagation speed of the surge is V, then the distance La to the accident point is La=V-ta. Comparing with the case of the conventional equation (7) mentioned above, the term 70 becomes (), and it can be seen that to, which had a large error in the synchronous line, can be ignored.

(Effects of the Invention) As explained above, according to the fault point locating method of the present invention, it is possible to ignore the influence of the transmission time delay that occurs in the synchronous line in the conventional method, and the accuracy of fault point locating is improved. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of a specific example of the method for locating fault points of power cables according to the present invention. FIG. 2 is a block diagram of a conventional power cable failure point locating method. 1... Power cable, 2a, 2b... Surge current detection sensor light (CT), 3... Surge current, 4a14
b...Pulse generator, 5a15b...Time counter, 6...Transmission terminal, 7...Central processing unit, 8a,
8b, 9... optical fiber cable.

Claims (3)

[Claims] (1) A surge current detection sensor and a timing counter that is driven and stopped by the information from the sensor are installed at both ends of the power cable, and the information from the surge current detection sensor is sent to the timing counters of the own station and adjacent stations, A power cable failure point locating method characterized by transmitting each count value to a central processing unit for calculation and display. (2) The clock counters installed at both terminals have different signs when driven by the surge current detection sensor of the local station and the surge current detection sensor of the adjacent station. method for locating fault points in power cables. (3) The distance to the accident point is calculated by canceling the transmission time delay of the pulse signal sent to the time counter of the adjacent station from the two count values of the time counters installed at both terminals. 1) Method for locating fault points of power cables as described.