JPS62121370A - Ground-fault detecting device - Google Patents

Abstract

PURPOSE:To detect exactly and quickly a ground-fault point by providing plural pressure detecting devices for detecting a pressure buildup caused by a ground- fault current, in the axial direction in a duct line, and measuring a time difference detected by two pressure devices. CONSTITUTION:As for a gas insulating bus 1, plural containers 2 are connected by a flange 3, and plural conductors 5 are inserted through a contact 4 of the flange 3. Also, the conductor 5 is supported by an insulating support member 6, and contained together with an insulating gas. In such a state, for instance, in case a ground-fault is generated in a point A, a pressure buildup caused by a ground-fault current flowing to a grounding conductor 8 is detected by pressure detecting devices 9-I, 9-III. The device 9-I is nearer than 9-III to the ground-fault point A, therefore, the detection time is quickened. Accordingly, a time difference detected by the devices 9-I, 9-III is measured by a time measuring device 10, and in an arithmetic unit 12, the ground-fault point A is calculated by dimensions such as a distance extending from the ground-fault point A to the devices 9-I, 9-III, a velocity of propagation of a pressure wave in the bus 1, etc. Also, by executing an output display on a display device 12, the ground- fault point A can be detected exactly and quickly.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a ground fault detection device for gas insulated electrical equipment.
In particular, the present invention relates to a ground fault detection device suitable for gas-insulated busbars.

[Technical background of the invention and its problems]

Generally, a gas insulated bus bar is constructed by insulating and supporting a conductor inserted into a conduit filled with an insulating gas such as SF6 gas using an insulating material. If a ground fault occurs on this gas-insulated bus, the conductor and the conduit will be short-circuited by the ground fault arc current, the conductor and conduit surfaces will be roughened, and the insulator will be carbonized, causing the gas-insulated bus to withstand Voltage performance will deteriorate. For this reason, it is necessary to disassemble and inspect the gas-insulated busbars, but since some of them are several kilometers long, it is necessary to detect ground faults accurately and quickly.

Therefore, in the conventional single-point grounding system in which the conduit is insulated between each container and grounded at a point, a current transformer is installed in the grounding wire connected to each container, and a ground fault is detected depending on the presence or absence of ground fault current. was being detected. However, when this method is applied to a multi-point grounding system that does not insulate each container, the impedance of the grounding wire with respect to the container is much larger.
The magnitude and phase of the current measured in each current transformer are almost the same, making it impossible to detect a ground fault point.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a ground fault point detection device capable of eliminating the above drawbacks and detecting ground faults accurately and quickly.

[Summary of the Invention] In order to achieve the above object, the present invention includes a plurality of pressure detection devices that detect a pressure increase due to a ground fault current generated in a pipeline at predetermined intervals in the axial direction within the pipeline. established,
The time difference between the inputs from two of these pressure detection devices is measured by a time measurement device, and the calculation device calculates the ground fault point based on this time difference and displays it on the display device, making it possible to accurately and Rapid ground fault detection is possible.

[Embodiments of the invention]

The outline of the present invention will be explained below with reference to FIG.

FIG. 1 shows a gas insulated bus bar as an example of gas insulated electrical equipment. The gas insulator a1 has a plurality of conductors 5 connected via contacts 4 at the flange 3 inside a conduit constructed by connecting a plurality of containers 2 at each other's flanges 3 and electrically connecting them. The conductor 5 is supported by an insulating support member 6 and housed together with SFs gas, which is an insulating gas. Further, each container 2 is grounded via a ground terminal 'a8' from a ground terminal 7 provided for each container. In this embodiment, as an example, a case is shown in which three containers 2 are connected to form a conduit, and from the left side in FIG.
and ■Explained as sections. However, it is also possible to connect a device other than the container 2, such as a bellows, to the middle or end of the connected container 2. moreover.

The containers 2 in section (1) and the containers 2 in section (2) are provided with pressure detection devices 9-1 and 9-111 that detect the pressure inside the containers and output it as a signal. In addition, the pressure detection devices 9-I and 9-
Ill outputs a change in pressure as a change in current, a change in light amount, or the like. And surface pressure detection device 9
-1.9-m is connected to the time meter d1 device 10. This time measuring device 10 includes pressure detecting devices 9-■, 9-III.
It measures the time difference until reaching . Also,
A calculation device 11 for calculating the ground fault point is connected to the time measurement device 10, and a display device 12 for displaying the ground fault point is connected to the calculation device 11.

Next, the basic operation of this configuration will be explained.

Assuming that a ground fault occurs at point A in FIG. 1, the waveform of the ground fault current flowing through the grounding wire 8 is shown by an inset curve in FIG. Moreover, the pressure waveforms in the pipe line detected by the pressure detection devices 9-1 and 9-2 are shown by curve B and curve C, respectively. Then, the time of occurrence of the ground fault is t.

Then, the pressure increase change due to the ground fault current is detected by the pressure detection device 9.
It occurs at time t at the -I position, and at time t2 at the pressure detection device 9-■■ position. In addition, for the ground fault point, the pressure detection device R
Since 9-I is closer than 9-l1l, tl<tz.

Here, the distance between the pressure detection devices 9-1 and 9-■ is L[
m], and the distance from the ground fault point A to the pressure detection device 9-1.9-■ is respectively n1. Q2 (m), and the pressure wave propagation speed in the gas insulated bus 1 is v (m/s), then a□+Q2=
L ・・・・・・ (υQz−Q
1= v (ti tx) ”'”'
(21. From equation 0 and equation (■), -gx-ti(4-v(tz-ti))--■ can be obtained.In other words, the value of the time difference (12-1) is determined by the time measurement device 10. Since the values of L and v are known, the ground fault point A can be determined by calculating equation (3) with the arithmetic device 11 and the result can be displayed on the display device 12. .

A concrete ground fault detection device will be explained with reference to FIG. A plurality of pressure detection devices 9a, 9b, 9c, and 9d are provided on the gas insulated bus bar 1 at predetermined intervals in the axial direction.

9e+9f+ 9g+ and 9h are provided. An OR circuit 13 and a signal selection circuit 14 are connected to the pressure detection devices 119a-9h, respectively. An arithmetic unit @11 is connected to the OR circuit 13 and the signal selection circuit 14. This arithmetic unit 11 includes a CPU 11a, a RANllb, and a ROM11c.
It is equipped with The calculation device 11 also includes a time measurement device 1.
0a and a display device 12 are connected.

Next, the operation of this configuration will be explained. Since ground faults generally occur suddenly, one commonly used method involves scanning each pressure detection device 9a to 9h. However, when the number of scanning points increases,
This is not preferable because it may cause a detection error in detecting the time of occurrence of a ground fault. Therefore, if any of the first pressure detection devices 98 to 9h detects a pressure increase due to a ground fault, its output will always be 0.
The CPU 11 receives the interrupt signal 15 via the R circuit 13.
transmitted to a. The operation will be explained below with reference to the flowchart shown in FIG.

Upon receiving the interrupt signal 15, the CPU 11a transmits a time measurement start signal 16 to the time measurement device 10, thereby resetting the time measurement device 10 and starting time measurement (step A).
I).

Then, the selection signal 17 is transmitted from the CPU 11a to the signal selection circuit 14, the outputs of the pressure detection devices 98 to 9h are sequentially switched, and the location where the ground fault has occurred is determined based on the selection data 18. As a result, it is detected which output of the pressure detection devices 9a to 9h has caused an interrupt (step
A2). Here, it is assumed that an interruption occurs at the output of the pressure detection device [9c, that is, a ground fault occurs at the position closest to the pressure detection device 9c.

Next, it is determined which side of the pressure detection device 9c the ground fault point is occurring, that is, the pressure detection device [9b side or 9d side]. In other words, the selection signal 17 is sent from the CPU 11a.
is transmitted to the signal selection circuit 14, and the pressure detection devices 9b, 9
Judgment is made by switching the output of d (step A3
, A4).

If a pressure increase is detected by the pressure detection device 9d,
It is determined that the pressure has occurred in the direction of the pressure detection device 9d with the pressure detection device 9C as a reference, and this is determined to be detected by the CPU 11a based on the selection data 18.
(Step A5).

On the other hand, if a pressure increase is detected by the pressure detection device 9b,
It is determined that a ground fault has occurred in the direction of the pressure detection device 9b with respect to the pressure detection device 9c as a reference, and this is stored in the CPU 11a based on the selection data 18 (step A6).

Thereafter, a clock stop signal 19 is transmitted from the CPU 11a to the time measuring device 10. The time measurement device 10 stops measurement in response to the time measurement stop signal 19 (step 87).

That is, the time measuring device 10 starts measuring time based on the output signal of the pressure detecting device 9c that first detected the pressure increase due to the ground fault, and the time measuring device 10 stops timing.

The operating time of the time measurement device 10 is then transmitted to the CPU 11a and stored as time measurement result data 20 (step A8).

Furthermore, in the CPU 11a, the pressure detection devices 98 to
The position of 9h, the pressure wave propagation speed, etc. are stored as known information, and along with the time measurement result data 20, the distance measurement from the pressure detection device 9C is calculated using the formula (J).
Step A9).

Finally, the results obtained in step 80 are displayed on the display device 12 (step A10).

In this specific example, a plurality of pressure detection devices 98 to 9h are provided in a conduit formed by connecting a plurality of containers. The pressure increase due to the ground fault is detected by the pressure detection devices 9a to 9h provided apart from each other, and the time difference is measured by the time measurement device 10. Furthermore, by calculating this time difference using the calculation device 11, the position of the ground fault point can be detected quickly and accurately. Furthermore, the time measuring device 10 starts counting based on the output signal of the pressure detecting device that first detected the pressure increase due to the ground fault, and stops counting based on the output signal of the pressure detecting device that detects the second pressure increase. Therefore, the time required to detect the position of the ground fault can be minimized, and unnecessary operations such as third and subsequent measurements in the arithmetic device 11 and the time measuring device 10 can be omitted. Since the OR circuit 13 is connected to the pressure detection devices 98 to 9h and the CPU 11a is operated as the output of the interrupt signal 15 of the OR circuit 13, it is possible to accurately measure the time when a ground fault occurs. Further, the pressure detection devices 9b on both sides of the pressure detection device 9c that detected the first pressure detection device.

Since only 9d is determined to be detected second, the ground fault detection speed can be increased. Also.

Since the ground fault point is first displayed based on the distance and direction from the pressure detection device 9c, the ground fault point can be easily confirmed and the gas insulated bus bar can be disassembled and inspected in a short time.

In this embodiment, only the gas-insulated busbar has been described, but the invention is not limited to this, and even if other gas-insulated electric equipment is interposed in the middle or at the end, the same structure can be obtained. Effects can be obtained.

〔Effect of the invention〕

As explained above, in the present invention, a plurality of pressure detection devices are provided at predetermined intervals in the axial direction of the pipe to detect a pressure increase due to a ground fault current generated in the pipe. Since the ground fault point is detected by measuring the time difference detected by the two pressure detection devices, it is possible to provide a ground fault point detection device that can accurately and quickly detect the ground fault point.

[Brief explanation of drawings]

Fig. 1 shows a schematic configuration of the ground fault detection device of the present invention, Fig. 2 shows a ground fault current waveform and pressure waveform, and Fig. 3 shows a specific example of the ground fault detection device of Fig. 1. FIG. 4 is a flowchart showing the operation of the ground fault detection device shown in FIG. 3. 1... Gas insulated bus bar, 2... Container, 3...
・Flange, 4...Contact, 5...Conductor, 6...Supporting member, 7...Grounding terminal, 8...Grounding wire, 9-1.9-
m, 9a to 9h--pressure detection device, 10... time measuring device, 11... arithmetic device, 12...
Display device, 13...OR circuit. 14... Signal selection circuit, 15... Interrupt signal, 16... Timing start signal, 17... Selection signal, 18... Selection data, 19...
Timing stop signal, 20... Timing result data. Agent Patent Attorney Noriyuki Chika Yudo Hirofumi Mitsumata Figure 1

Claims (5)

[Claims] (1) A plurality of pressure detection devices installed at predetermined intervals in the axial direction in a conduit in which a conductor is insulated and housed inside along with an insulating gas, and detecting a pressure increase due to a ground fault current generated in the conduit; A time measurement device that measures the time difference between inputs from two of the pressure detection devices; a calculation device that calculates the ground fault point from the time difference and specifications such as the installation position of the pressure detection devices; A ground fault detection device comprising: a display device connected to an arithmetic device and displaying the output thereof. (2) The earth fault detection device according to claim (1), wherein the time measurement device starts measuring time in response to an interrupt signal from the pressure detection device that first detects a pressure increase. (3) The time measuring device starts measuring time based on the output of the pressure detecting device that first detects the pressure increase, and stops timing based on the output of the pressure detecting device that detects the pressure increase second. The earth fault detection device described in item 1). (4) The earth fault point detection device according to claim (1), wherein the time measurement device stops measuring time by the output of one of the pressure detection devices on either side of the pressure detection device that first detects a pressure increase. . (5) The ground fault detection device according to claim (1), wherein the display device displays the ground fault point in terms of distance and direction from the pressure detection device that first detected the pressure increase.