JPH0363711B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a fault section locating device for locating a section in which a ground fault fault has occurred in a power cable.

[Prior Art] Power cables are indispensable equipment for today's power transmission operations, and accidents involving these equipment can have a very serious impact on today's highly electrified society, and in some cases can cause damage in all directions. Social functions may be paralyzed.

For this reason, although various measures have been taken to prevent accidents in power cables, it has not yet been possible to completely eliminate ground fault accidents. Therefore, in the event that such an accident occurs, the next best challenge is to quickly determine the location where it occurred so that restoration work can be carried out as soon as possible.

Conventionally, the method of detecting the location of an accident has been to detect fault currents using current transformers installed in cables within the substation, and to locate the fault section based on their magnitude. Because accident location can only be done in the section between the lines, the exact point of the accident is unknown at the time of the accident.

Therefore, in order to accurately locate the section where the accident occurred, it is necessary to conduct a separate investigation after the accident using methods such as the Murray loop method, which is a factor that significantly slows down the recovery work.

[Object of the Invention] In view of the above situation, an object of the present invention is to provide an accident area locating device that can identify the accident area at the same time as the accident occurs.

[Summary and operation of the invention] The present invention provides a structure in which a current transformer is installed on the bond wire of a metal sheath of a power cable, and a light emitting element is installed on the secondary side of this current transformer so that the polarity is reversed between the current transformers in adjacent sections. The light from two adjacent light-emitting elements is guided through optical fibers, photoelectrically converted, and the AND output of each electric signal is obtained.

In this configuration, since the detection point and the management location are connected via optical fiber, malfunctions due to disturbance noise such as electromagnetic induction are less likely to occur, and optical fibers can be easily installed along power cables. The entire equipment becomes a simple and inexpensive accident area locating device.

[Embodiment] A specific configuration of the accident zone locating device of the present invention will be explained with reference to the drawings showing one embodiment.

In FIG. 1, 1 is a power cable, 2 is a metal sheath bond wire, 3 is an ordinary connection box, and 4 is an insulated connection box.

One line of the bond line 2 within the location area is inserted into current transformers 51, 52, 53 at once, and light emitting elements 61, 62, 63 are provided on the secondary side of each current transformer.

The light emitting elements 61, 62, and 63 are connected so that adjacent sections have opposite polarities.

A detailed state of connecting the light emitting element 61 to the secondary side of the current transformer 51 is shown in FIG.

In FIG. 2, R ₁ and R ₂ are resistors, D is a diode, and ZD is a Zener diode.

The light from the light emitting elements 61, 62, 63 is guided to photoelectric converters 71, 72, 73 by optical fibers 211, 212, 213 for locating the accident area, and then connected to the AND circuit 8.
1 and 82 to obtain the AND output.

9 is a relay transmission device, and 221 and 222 are optical fibers for information transmission.

For example, if the cable breaks down at point B in FIG. 1 and a ground fault occurs, the fault current will be shunted in the direction of the arrow, and the current will also flow through the bond wire 2.

At this time, currents in opposite directions flow through the current transformer 51 and the adjacent current transformer 52, but the light emitting elements 61 and 62 connected to each other have opposite polarities, so they emit light at the same time.

On the other hand, current flows in the same direction in the current transformer 53 on the opposite side adjacent to the current transformer 51, and the light emitting elements 61 and 63 connected to each have opposite polarities, so they emit light alternately and at the same time. It does not emit light.

Therefore, the outputs of the photoelectric converters 71, 72, 73 that receive the light emitted from the light emitting elements 61, 62, 63 are ANDed.
The outputs of circuits 81 and 82 are as shown in FIG.

3 is a time chart, 10 is the output waveform of the photoelectric converter 71, 11 is the photoelectric converter 72, 12 is the output waveform of the photoelectric converter 73, 13 is the AND circuit 81, and 14 is the output waveform of the AND circuit 82. shows.

As is clear from Fig. 3, the logical product output of the section including the accident point is high level, and the logical product output of other sections is low level, so it is possible to locate the section where the accident occurred. .

The AND output is input to the relay transmission device 9, and the information is transmitted to the appropriate management location via the information transmission optical fiber 222.

Note that the fault current detection position does not need to be limited to the locations of all insulating junction boxes, and may be omitted as appropriate.

In addition, there is no problem in principle in using the grounding wire of an air termination box, gas termination box, etc. in place of the cross bond wire of an insulated junction box to detect fault current. .

If it is difficult to insert cross bond wires or ground wires into the same current transformer, use multiple current transformers and connect their secondary sides in parallel. It is also possible to have

[Effects of the Invention] As explained above, the fault area locating device of the present invention utilizes the zero-sequence current of the cross-bond wire as the fault current, and uses optical fiber as the transmission line, so electromagnetic induction, etc. There is no malfunction due to disturbance noise, the overall configuration is simple and inexpensive, and the area where the accident occurs can be accurately located.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention, Fig. 2 is a partial detailed explanatory diagram of Fig. 1, and Fig. 3 is an output waveform time chart of a photoelectric converter and an AND circuit. . 1; Power cable, 2; Metal sheath bond wire,
3; Ordinary junction box, 4; Insulated junction box, 51, 52,
53; Current transformer, 61, 62, 63,; Light emitting element, 71, 72, 73,; Photoelectric converter, 81,
82; AND circuit, 9; Relay transmission device, 211,
212, 213; Optical fiber for locating accident area, 2
21, 222; Optical fiber for information transmission.

Claims (1)

[Claims] 1. A current transformer is installed in the metal sheath bond wire of the insulated connection part of the power cable, and the light emitting elements on the secondary side of this current transformer have opposite polarity between the current transformers in adjacent sections. A photoelectric converter is provided for photoelectrically converting the output of the light emitting element guided by the optical fiber.
1. A power cable accident section locating device, characterized in that it is provided with an AND circuit that obtains a logical product of two electrical signals brought from light emitting elements in adjacent sections. 2 One line of metal sheathed bond wire is collectively
2. The power cable fault area locating device according to claim 1, wherein the device is inserted into a current transformer and is configured to be able to detect a zero-sequence current component of a sheath current. 3. The first device is characterized in that the secondary outputs of the current transformers installed in the metal sheath bond wire in the same line are connected in parallel, and the zero-sequence current component of the sheath current can be detected. Power cable fault area locating device as described in Section 1.