JPH01123169A - Method for detecting trouble point of power cable - Google Patents

Abstract

PURPOSE:To reduce cost, by a method wherein an operation apparatus is operated only for a predetermined time when the detection value of an electromagnetic coil for detecting an accident current exceeds a predetermined value and the output of a microphone is read within said time and a signal is outputted when said output value is equal to or more than background noise. CONSTITUTION:When an electric accident is generated in power cables 10, a non- equilibrium current flows to three cables 10 and, therefore, magnetic flux is generated outside the cables 10 and the magnetic field thereof is detected by an electromagnetic coil 52. The magnitude of said magnetic field is compared with that of the magnetic field at a usual time and, when the former is at least twice or more, an operation apparatus 56 is operated for a predetermined time and the sound pressure data from a microphone 58 is read during this time. When the sound pressure level thereof is a predetermined value or more, alarm output 61 is transmitted. Further, the output 61 transmitted from the apparatus 56 is recorded and investigated by a receiving apparatus 62. That is, when it is supposed that an accident point 20 is present between points C, D, a sonic wave 40 propagates left and right, and arrives at the points C, D when the operation time of the apparatus 56 is elapsed and only the apparatuses 50 at the points C, D emit alarm output signals. Therefore, a section where an accident is generated can be instantaneously detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for detecting a failure point of an electric cable installed in a tunnel, and particularly to a method for detecting a section where a ground fault occurs.

[Prior art] When #&t'lS failure occurs in a cable in a tunnel, 20
At the same time, a ground fault current of ~50 kA flows and a loud sound (13
0 to 150 ho) occurs. Also, the sound pressure is
Propagates at a constant speed within the tunnel.

A method for locating a ground fault point using this phenomenon has been proposed (Japanese Patent Application No. 56159/1982).

A brief explanation of this technology is as follows.

In FIG. 4, 30 is a tunnel, and 10 is an electric cable. However, although the power cable 10 is shown as a model with only one line, it actually includes a plurality of lines as shown in FIG.

A sound pressure sensor 32 uses a microphone, for example.

This is A, B, and C with appropriate spacing.

D. Attach to the ceiling of the tunnel 30 at the point ----.

Is 34 a record? It has an internal clock, like a microprocessor, and under this control reads and stores data at regular intervals.

A magnetic field sensor 36 is installed at or near the cross bond wire 14 of the insulated junction box 12, and serves to detect a large current generated at the time of a ground fault, and activate the recording device 34 with this signal.

38 is central processing? CD, the data is collected from the recording device 34 mentioned above, and the sound source is comprehensively determined and displayed.

- When a ground fault occurs at the fault point 20 in Figure 4, the sound waves 40 propagate left and right.

Also, as described above, the recording device 34 starts at the same time as the ground fault occurs, detects the sound coming into the microphone at intervals controlled by the internal clock (for example, 0.01 sec), and detects the sound J'l! ! Measure the time it takes for the sound pressure of the circuit to reach the target.

As shown in FIG. 6, for example, the propagation time (t1+t,) and the sound intensity are different between point B and point A.

That is, the propagation time is shorter and the sound intensity is greater at point B, which is closer to the accident point 20.

This relationship is the same at points C and D, and the above data is processed centrally! e! '138, the direction of the accident point 20 and the distance from point B, for example, are known.

[Problems to be Solved by the Invention] As mentioned above, the description is made for each location. 134 is necessary, and the central processing unit 38 compares the sound pressure intensity and arrival time for each point.

I need to calculate the distance.

Therefore, the device and calculation method become complicated, and expensive equipment is required.

[Means for Solving the Problems] As shown in FIGS. 1 and 3, the present invention provides (1) a detection device having at least an electromagnetic coil 52 for fault current detection, an arithmetic device 56, and a microphone 58; r150 at a plurality of positions along the power cable lO, (2) operate the arithmetic device 56 for a predetermined time from when the detected value of the electromagnetic coil 52 exceeds a predetermined value, and within that time, The output of the microphone 58 is read and an output signal is output only when the value is greater than background noise.

By adopting this method, the above problem was solved.

[Example] [11 configurations: As shown in Figure 1, a detection device! 150 is electric cable 1
0 in the longitudinal direction. The number is 10 electric cables.
There shall be at least one location for each section.

Further, each detection device 2!50 is attached to the ceiling of the tunnel 30, for example, as shown in Fig. ff12.

The configuration of each detection device 50 is shown in FIG.

52 is an electromagnetic coil, which is connected to the power cable 1 due to a fault current.
This is for detecting the magnetic field generated at zero.

A comparator section 54 compares whether the voltage generated by the electromagnetic coil 52 is larger than a normal value, and if it is larger, activates the arithmetic unit 56 described below.

58 is a microphone for sound pressure detection.

60 is an A/D converter.

The arithmetic unit 56 is activated by the signal from the comparator section 54 as described above, and operates for a predetermined period of time.

During this time, the presence or absence of sound pressure is detected, and an alarm output signal is issued only when the sound pressure exceeds a certain value.

62 is a receiving device that records the signals of each detection device 50, compares them, and makes decisions.

[2] Effect: (1) When the power cable lO is operating normally.

Since a balanced current flows through the three electric cables 1o, magnetic flux is rarely generated outside the electric cable 10.

(2) When an electrical accident occurs in the ffi cable lO.

Since an unbalanced current flows through the three power cables 1o, magnetic flux is generated outside the power cable 1o.

The Mll cocoil 52 detects the magnetic field generated outside.

The comparator unit 54 compares the magnitude of the magnetic field with the magnitude of the magnetic field during normal operation, and when the magnitude is at least twice as large,
The arithmetic unit 56 is activated.

(3) The arithmetic unit 56 operates for a predetermined time (about 2 seconds).

During this time, sound pressure information from the microphone 58 is read.

When the sound pressure level is equal to or higher than a predetermined value (background noise generated by a blower, etc.), an alarm output 61 is transmitted.

(4) The receiving device 6 receives the alarm output sent by each detection device 50.
2, the music to be recorded and compared as follows, that is, as shown in FIG. And if the accident point 20 is between C and D, then the situation will be as follows.

As mentioned above, the sound waves 40 propagate both left and right.

Then, as described above, when the operation time (for example, 2 seconds) of the computing device 56 has elapsed, the sound wave 40 is emitted.

For example, if the vehicle has reached points C and D but has not yet reached locations B and E, which are farther away, only the detection devices 50 at C and D will issue an alarm output signal.

Therefore, the section where the accident occurred can be instantly known.

[Effects of the Invention 1 (1) Even if a large number of lines are installed in the tunnel 30, one detection device 50 can detect the occurrence of an accident at one point.

Therefore, it becomes an inexpensive system.

(2) There is no need to attach a magnetic field sensor directly to the power cable or crosspond wire, making construction easier.

(3) It can be easily applied to existing railway lines.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanatory diagram of the present invention. FIG. 2 is an explanatory diagram of the mounting position of the detection device 50, FIG. 3 is an explanatory diagram of the detection device 50, and FIG. 4 and subsequent figures relate to the prior art. Figure j14 is a schematic explanatory diagram of the configuration. Figure f55 is an explanatory diagram of the mounting position of the sound pressure sensor 32, and Figure 6 is an explanatory diagram showing an example of recording of sound waves. 10: Electric cable 12: Insulated junction box 14: Cross pond wire 16: Ordinary junction box 20: Accident point 30: Sinus conductor 32: Sound pressure sensor 34: Recording device 36: Magnetic field sensor 38: Central processing unit 40: Sound wave 50 : Detection device 52 : Electromagnetic coil 54 : Comparator unit 56 : Arithmetic device 58 : Microphone 60 : A/D converter 62 : Receiving device Patent applicant Chubu Electric Power Co., Ltd. Fujikura Electric Cable Co., Ltd.

Claims (1)

[Claims] A detection device (50) having at least an electromagnetic coil (52) for fault current detection, a calculation device (56), and a microphone (58) is arranged at a plurality of positions along the power cable (10). ) when the detected value exceeds a predetermined value, the arithmetic device (56) is operated for a predetermined time, and within that time, the output of the microphone (58) is read, and the output value is greater than background noise. A method for detecting a fault point in a power cable, characterized in that an output signal is output only when the power cable is in use.