JPH0972938A - Grounding-cable discriminating method and automatic grounding apparatus using the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To select a working cable correctly and to perform grounding safely. SOLUTION: The separating ends of the three-phase lines of electric cables separated from an electric power system are shorted by sort-circuit instrument 2', respectively. A master station 10 is provided at one line of the grounding line among the shorted three-phase lines, and a discriminating pilot signal is injected. Furthermore, a slave station 11 is arranged in the working block including the shorted three-phase lines, and a transformer 16' is attached to each line. The current or voltage level in the commercial frequency band of each line is measured, Thus, the three-phase lines, wherein the commercial frequency is not detected, are specified. Then, the transformer 16, is sequentially attached at each phase of the specified three-phase lines, and the pilot signal is measured. The line, wherein the measured value becomes twice the other value, is made to be the grounding line. Thus, the working cable 1 can be selected without fail. The automatic grounding apparatus, which can safely perform the grounding of the working cable 1, is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grounding cable judging method for judging a working line to be grounded from a large number of power cables and an automatic grounding apparatus using the judging method, and more particularly to its working. The present invention relates to a method of discriminating a grounding cable capable of safely performing an automatic grounding device and an automatic grounding device using the method.

[0002]

2. Description of the Related Art Electric power work For example, when cutting and branching a power cable laid in an underground ditch, etc., before starting the work, in order to prevent an electric shock accident, work on the power cable Disconnect the work cable from the power grid and ground both ends of the work cable in the disconnected section.

At this time, at the work site, for safety, the protective sheath of the work cable, the electrostatic shield, and the semi-conductive tape are cut into an appropriate size, and an electric potential is detected from the last remaining insulator to detect an electric potential. After confirming that the work cable is disconnected from the power transmission system, the ground electrode is driven into the work cable to ground it.

However, in a power transmission system laid in such an underground trench, it is almost the case that a plurality of similar cables are arranged together in addition to a work cable that must be grounded. You may choose the wrong cable to perform the grounding work. In that case,
In the above-mentioned method, the mistake can be recognized when the electric potential is detected by detecting the voltage. For this reason, if you select the wrong cable, repair the cable that had the outer jacket cut out in the reverse order, and then perform the grounding work for the other cable again, that is, cut the outer jacket of the cable and perform power detection. After confirming that the work cable is disconnected from the power transmission system, the ground electrode must be driven into the work cable for grounding.

Therefore, there is a problem that it is troublesome and extremely inefficient. In addition, if the wrong cable is selected, a power failure or an electric shock may occur, which is a safety issue.

As a method for solving this problem, conventionally, a discrimination method using a transmitter and a search coil has been used.

In this method, as shown in FIG. 7, one end side of the power cable 1 to be discriminated is short-circuited by the short-circuit cord 2 and a signal of a specific frequency is injected from the oscillator 3 to the other end side. In this way, the search coil 5 connected to the receiver 4 is brought close to the cable 1 and the current flowing through the closed circuit formed by the short-circuit cord 2 is detected to determine the states of dead line and live line.

[0008]

However, in the method using the above search coil, when a large number of power cables are detected in adjacent manholes, etc., the measurement cable is detected from the electromagnetic field generated by other power cables. There is a problem that the ratio of the signal voltage to the noise voltage of the search coil decreases due to the induction itself and the induction environment in the manhole, and the signal voltage becomes undetectable.

In this case, the induction received by the search coil is
The search coil, its iron core, and the surrounding electromagnetic field can be prevented to some extent by providing an electromagnetic shield, but there is a problem that even the induction received by the power cable itself cannot be prevented.

Therefore, the first object of the present invention is to make it possible to select a work cable without fail even if there is electromagnetic induction noise from another cable, and the selected work cable. A second object is to provide an automatic grounding device capable of safely grounding the vehicle.

[0011]

In order to solve the above-mentioned problems, in the invention according to claim 1, the separating ends of the three-phase lines of the power cable separated from the power system are short-circuited by a short-circuiting device, and the short-circuiting is performed. The pilot signal current for discrimination is injected into the grounding line of the three-phase line, and a transformer is attached to each line in the construction section including the short-circuited three-phase line, and the current in the commercial frequency band region of each line is Alternatively, after the voltage level is measured and it is detected that the current or voltage is not measured, a transformer is sequentially installed for each phase of the three-phase line, and a pilot signal for discrimination is measured, and the measured value is the other two. The method of using the doubled line as the ground line was adopted.

According to the second aspect of the present invention, the master station for injecting the pilot signal current into the power cable and the pilot signal current injected into the power cable by the master station are detected to drive the automatic grounder. Consisting of a slave station that attaches a ground wire to a power cable, the master station, a transformer that is attached to the power cable, and a pilot signal generating means for injecting a discrimination pilot signal into the power cable through the transformer, A master station side communication means for transmitting and receiving a preparation completion signal, an operation signal, and a grounding completion signal to and from the slave station, an operation switch for transmitting the operation signal to the master station side communication means, and the communication means for receiving The slave station is attached to the power cable, and the slave station is attached to the power cable. Monitoring means for monitoring the presence or absence of commercial frequency current flowing through the power cable through the transformer, detecting means for detecting a pilot signal transmitted by the power cable from the master station through the transformer, and the detecting means. Notification means for notifying the level of the detected pilot signal, slave station side communication means for transmitting and receiving the preparation completion signal, operation signal and grounding completion signal between the master station and the slave station side communication means With a confirmation switch to send the, and the operation switch of the automatic grounder,
The automatic grounder has a grounding means for bringing the grounding electrode connected to the grounding wire into contact with the center conductor of the power cable by the advancing mechanism of the automatic connecting device connected to the operation switch of the slave station; and the grounding electrode by the grounding means. When it comes into contact with the center conductor of the power cable, a structure is provided which is provided with a grounding confirmation means which outputs a grounding confirmation signal and outputs the grounding signal to the slave station side communication means.

[0013]

In the detecting method of the invention according to claim 1 configured as described above, the separated ends of the three-phase lines of the power cable separated from the power system are short-circuited by a short-circuit tool to form a closed circuit.

A pilot signal current for discrimination is injected into one line of the specified three-phase line, and a transformer is attached to each line of the construction section including the short-circuited three-phase line. Measure the current or voltage level in the commercial frequency band.

At this time, the current or voltage level difference between the dead line and the live line to be measured becomes very large, so that the short-circuited three-phase line can be easily specified.

Next, transformers are sequentially attached to the three-phase lines specified as described above, and the current level of the pilot signal is measured. At this time, the measurement level was obtained by short-circuiting the separation ends at both ends of the three-phase line with a short-circuit tool.
Since the other two wires will be connected in parallel to the one line injected with the pilot signal current, the detection level of the one line injected with the pilot signal current will be twice that of the other line, and the measurement result will be twice that. The ground line can be easily specified from.
At that time, the induction that the power cable receives from the external magnetic field is common to the three-phase line, so even if there is a mixture of power cables that have the same induction failure as the signal frequency, the work cable and the other cables do not exist. Can be clearly distinguished.

In the invention according to claim 2, for example, the transformer of the master station is disconnected from the power system by a worker on the master station side, and the separated separation ends are respectively short-circuited by the short-circuiting device, whereby the work cable is cut. It is attached to the one-line ground wire of the three-phase line that has been certified as. Then, the pilot signal is injected from the pilot signal generating means through the transformer attached to the one line.

At this time, in the slave station, a clamp-type transformer that can be attached to the power cable by a worker on the slave station side is attached to each cable, and the presence or absence of the commercial frequency current flowing through each cable is measured by the monitoring means. By measuring the presence / absence of current at the commercial frequency in this manner, it is possible to discriminate between the live line and the dead line of the line, so that the working cable short-circuited by the short-circuit device can be specified. When the working cables are specified in this manner, transformers are sequentially attached to the specified three-phase working cables, and the level of the pilot signal of each cable is detected by the detection means. At this time, since the level of the measured pilot signal of each line is notified by the annunciator, a line that is twice as high as the other line from the measurement level informed by the annunciator can be determined as the ground line. .

Further, when the grounding wire is determined in this manner, an automatic grounding device is attached to the working cable determined as the grounding wire, and when the confirmation switch is operated, a preparation completion signal is transmitted by the slave station side communication means and is transmitted. The preparation completion signal is received by the master station side communication means, and is notified by the notification means. Therefore, when the master station side operator confirms the notification, operates the operation switch, and transmits the operation signal from the master station side communication means, the transmitted operation signal is received by the slave station side communication means, and by the notification means. Since this is notified, the operator of the slave station side checks the operation signal again, and then operates the operation switch to operate the automatic grounder. Then, the grounding means of the automatic grounder operates and the advancing mechanism advances the ground electrode toward the center conductor of the cable, and by the advance, when the ground electrode comes into contact with the center conductor of the cable with sufficient pressure, The advancing mechanism is automatically stopped by the detecting means, and a grounding operation completion signal is transmitted to the master station via the slave station.

Upon receiving the grounding operation completion signal, the master station sends a grounding detection signal to the power cable to confirm that the power cable is completely grounded, and then informs all workers that grounding work has been completed. To do.

[0021]

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

FIG. 1 shows an embodiment of the automatic grounding device of the invention according to claim 2 which uses the method for judging the ground cable of the invention according to claim 1.

As shown in FIG. 1, this automatic grounding device
It is composed of a master station 10 and a slave station 11, and the master station 10
Comprises a pilot signal generating means and a master station side communication means,
On the other hand, since the slave station 11 includes the commercial frequency monitoring means, the pilot signal detecting means and the slave station side communication means, the master station 1
Data is transmitted and received between 0 and the slave station 11, and the power cable 1 is automatically grounded.

At this time, in the embodiment, the master station 10 and the slave station 11
Data transmission and reception between them is performed by using carriers of different frequencies.

That is, the master station 10 includes a microcomputer 12, a band pass filter 13, a receiving amplifier 14,
Reception circuit 17 including A / D converter 15 and transformer 16
And a transmission circuit 19 including a transmission amplifier 18 and a transformer 16, and the microcomputer 12 includes:
A notification unit including a lamp 20, a buzzer 21, and an LCD display 22, a signal generator 23, and a confirmation switch S1 are provided. Then, these transmitting circuit 19 and receiving circuit 1
7 together form a pilot signal generating means and a master station side communication means.

At this time, for example, the pilot signal is generated by the microcomputer 12 by outputting the oscillation output of the signal generator 23 in association with the digital codes "1" and "0", and the generation thereof. The power of the pilot signal is amplified by the transmission amplifier 18, and the amplified pilot signal is injected into the power cable 1 through the transformer 16.

That is, in the case of the embodiment, the signal generator 23
Is assumed to oscillate a sine wave in the audio band of about 1000 Hz, and the oscillation output is encoded by the microcomputer 12 by turning on / off the analog switch 25 in response to a digital signal as shown in FIG. Encode).

Further, the master station communication means encodes the output of the signal generator 23 into a digital signal corresponding to the operation signal by the microcomputer 12 in the same manner as the pilot signal at the time of transmission, and by the transmission amplifier 18. The power is amplified and injected into the power cable 1 via the transformer 16. On the other hand, at the time of reception, the bandpass filter 13 connected to the transformer 16 selects and receives the reception signal detected by the transformer 16, and the reception amplifier 14 amplifies the selected and received signal, and the A / D The converter 15 performs A / D conversion and inputs to the microcomputer 12.

In the microcomputer 12, the input signal is decoded (decoded) into a code and notified by the notification means. At this time, the center frequency of the bandpass filter 13 is set to 2000 Hz which is a transmission carrier of the slave station side communication means described later.

The slave station 11 is the microcomputer 1.
2 ', A / D converter 15', receiving amplifier 14 ', bandpass filter 13', transformer 16 ', receiving circuit 17', microcomputer 12 ', transmitting amplifier 18', transformer 16 'A transmitter circuit 19' consisting of
Microcomputer 12 ', A / D converter 15 ", receiving amplifier 14", low-pass filter 30, transformer 16
Commercial frequency monitoring circuit and an automatic grounder 32 connected to the microcomputer 12 'via a relay 31.
The microcomputer 12 'includes a lamp 20', a buzzer 21 ', and an LCD display 22'.
And a signal generator 23 ', a preparation completion switch S2, and an S3 switch which is a changeover switch for switching the processing of the microcomputer 12' between the commercial frequency monitoring and the grounding completion signal.

Transmitting circuit 19 'forming a communication means on the slave station side
Regarding the receiving circuit 17 ′ and the receiving circuit 17 ′, the oscillation frequency of the signal generator 23 ′ is set to 2000 Hz in the case of the embodiment, and the master station 10
By setting the oscillation frequency of the signal generator 23 on the side twice, it is set so that interference during transmission and reception does not occur. Therefore, by setting the center frequency of the band pass filter 13 'to 1000 Hz which is the transmission frequency of the master station 10, the transmission signal from the master station 10 can be received. The other configuration is the same as the communication means on the side of the master station 10, and therefore its explanation is omitted.

The commercial frequency monitoring means is composed of a low-pass filter 30 connected to the transformer 16 ', selectively receives a commercial frequency signal from the signals detected by the transformer 16', and receives the received signal from the receiving amplifier 14 "Amplification by", A / D conversion is performed by the A / D converter 15 ", and the result is input to the microcomputer 12 '.

The microcomputer 12 'discriminates whether the input signal is a signal having a cycle of 60 Hz or 50 Hz (Fourier transform of conversion data or detecting cycle of conversion data), and the signal The presence or absence and the magnitude of the commercial frequency current are measured (which can be detected from the A / D conversion output), and the value is displayed on the display 22 '.

Here, as shown in FIG. 3, the transformer 16 'is adapted to fit the cable 1 into the opening of a donut type ring core, and the magnetic field of the cable 1 fitted into the opening is converged by the core. However, the electromagnetic field generated by the cable 1 can be detected without being affected by the surrounding electromagnetic field.

Further, in the case of the embodiment, the cores are divided as shown in FIG. 3 and are connected by metal fittings provided on both sides.
It is a so-called split type CT that can be removed only by removing the metal fittings and splitting the core, so that the working efficiency can be improved.

The automatic grounder 32 comprises a control section 33 and an automatic grounder body 34.
In the case of the embodiment, as shown in FIG. 4, a drive motor M is provided, and the ground electrode E is attached to the tip of the slider mechanism 50 that moves forward and backward by the drive motor M. Then, the ground electrode E, which is connected to the ground, is press-fitted into the power cable 1 set in the mounting groove of the adapter A provided above the ground electrode E, so that the center electrode of the cable 1 is brought into contact.

At this time, the slider mechanism 50 of the embodiment
As shown in FIG. 5A, is composed of a slider shaft 52 provided in a cylindrical case 51 and a rotary shaft 53 fitted inside the slider shaft 52.

The rotating shaft 53 is rotatably supported by the case 51 via a bearing 54, and a gear member 55 is fitted to one end thereof.

As shown in FIG. 5A, the gear member 55 is provided around the gear provided on the motor shaft 56 and around the gear of the motor shaft at three equal intervals in this embodiment to prevent eccentricity. When the motor shaft 56 rotates, the rotation is transmitted to the gear member 55 via the first gear 57, and the rotation shaft 53 rotates. It is supposed to do.

Further, on the outer circumference of the rotary shaft 53, there is provided a thread groove which is screwed into the thread groove formed on the inner circumference of the slider shaft 52 which is fitted as described above. When the shaft 53 rotates, the slider shaft 52 moves up and down as shown in FIG. 5 (b). At this time, rotation of the slider shaft is restricted by the presser 58 so that the ground electrode E attached to the tip can be moved up and down without rotating, and the ground wire attached to the ground electrode E at the tip is twisted. To prevent it.

In FIG. 4, reference numeral 35 is a fixed belt for fixing the cable, reference numeral 36 is a fixed hook, reference numeral 37 is a hook fitting for hooking the fixed hook 36 at the end of the fixed belt 35, and reference numeral 38 is a ratchet type handle. Set the cable 1 in the cable adapter A as shown in
The cable 1 can be fixed by hanging the fixing belt 35 on the set cable 1, hooking the fixing hook 36 provided at the tip of the belt 35 on the hook metal fitting 37, and raising the ratchet type handle 38.

Reference numeral 39 is a window for confirming the position of the ground electrode E,
Reference numeral 40 is a connector for receiving a signal for remotely controlling the drive motor, and reference numeral 41 is a connector guide for protecting the connector 40.

The power cable adapter A is prepared so that the size of the mounting groove matches the diameter of the various cables 1 and can be freely replaced.

As shown in FIG. 1, the control unit 33 of the automatic grounder 32 is connected to the microcomputer 12 'of the slave station 11 and receives an operation signal from the slave station 11 to automatically complete the grounding. . When the grounding is completed, a completion signal is output to the slave station 11, and the slave station 11 receives the completion signal and transmits the grounding completion signal to the master station 10.

At this time, as a method for confirming the completion of the grounding operation of the automatic grounder 32, the method shown in FIG. 6 can be used. Therefore, the features and points to be considered of each of these methods will be described.

The method using the No. 1 resistance measuring device is to detect conduction between the ground electrode E and one core wire of the cable by a change in electric resistance and can be carried out relatively easily.
There is a drawback that the mechanical degree of contact (contact resistance) cannot be detected.

The method using the No. 2 resistance ratio meter is to measure the resistance ratio by the Merle-Loove method based on the loop resistance ratio to confirm the grounding of the cable core wire and to measure the specific distance from the measuring point to the grounding point. However, the measuring instrument used in this method needs to use a grounding instrument having a low resistance equivalent to that of the cable core wire.

The method of using the No. 3 penetration depth meter is a method of detecting the depth at which the ground electrode penetrates into the cable. For example, as a method of measuring the entrance position of the ground electrode E, a mechanical switch such as a microswitch is used. In addition to these methods, there are methods such as laser deviation meter, ultrasonic deviation meter, linear transformer, resistance deviation meter, and other electrical distance meters. Since the thickness is different, it is necessary to input in advance a set value that serves as a reference for each cable according to the thickness.

The No. 4 entry pressure gauge is a method of detecting the pressure when the ground electrode E enters the cable 1, and a pressure gauge is attached to the ground electrode E so that the grounding is performed when a predetermined pressure is reached. Considered completed. Therefore, it is necessary to confirm separately whether it has been grounded completely.

The method of using the No. 5 torque limiter is that the torque limiter is attached to the drive motor M so that the drive motor M is not press-fitted more than the torque. In this method, the hardness difference between the outer sheath of the cable 1 and the core wire is Since the penetration depth of the electrode E must be investigated so as not to penetrate beyond the predetermined depth, it is necessary to separately confirm whether or not the electrode E is completely grounded.

The method of using the No. 6 stopper is to attach a flange-shaped stopper to the ground electrode E so as not to allow the ground electrode E to penetrate beyond a predetermined depth. Although it is installed and forcedly pressed into that position, it is necessary to check separately whether it is completely grounded.

The method using the load ammeter of No. 7 is a method adopted when the driving energy of the ground electrode is proportional to the current, and due to the increase in the load current, the penetration depth and the complete contact with the central conductor This is a method of predicting that it is no longer possible to enter, and it is necessary to confirm separately whether it is completely grounded.

The method using the No. 8 waveform measuring device is to detect that the pulse wave traveling in the cable conductor is reflected by the change in the ground point impedance. After the grounding is completed, a pulse is injected between the conductor and the ground. Then, the degree of grounding and the distance to the grounding point are measured from the waveform of the reflected wave and the time delay, and it is an essential system especially when there are two or more grounding points. In this case, in order to improve the measurement accuracy, the short-circuit impedance is low at the commercial frequency and the pulse wave is the characteristic impedance of the cable, so that unnecessary reflection can be made less likely to occur, and therefore the measurement can be easily performed.

From the above results, in this embodiment, a method using a torque limiter and an overload current detector is used as a method for confirming the completion of the grounding operation of the automatic grounder 32.

Therefore, in this embodiment, the motor M of the automatic grounding device 32 is provided with a torque limiter.

The present invention is constructed as described above, and next,
A method of identifying the power cable will be described by describing its usage method.

In this automatic grounding device, 1. Installation of automatic grounding device 2. Track selection work 3. Installation of automatic grounding device 4. Grounding work 5. The grounding work can be completed by performing the five steps of work completion. Therefore, this work will be described step by step.

1. Installation of automatic grounding device First, the master station 10 is installed with one end side (ground side) of the work line as the work command side, and the slave station 11 and the automatic grounding device 32 are installed at the work location of the power cable 1 (usually in the manhole). To do.

That is, after the work line is cut off, the work line is brought into a three-phase collective short-circuit state by the short-circuit tool 2 ', and then the master station 10 is installed near one end of the work line. At this time, it is preferable that the short-circuit tool 2'used for short-circuiting the work line has a low contact resistance (0.5 Ω or less).

On the other hand, the slave station 11 is installed near the local work line, and the power source and the transformer 16 'are attached to one of the three-phase power cables 1.

After the installation work of the master station 10 and the slave station 11 is completed in this way, the line selection work is performed.

2. Line selection work (1) Turn on the main switch of the master station 10 to start the master station 10 and check the power supply voltage and the signal output voltage of the master station 10.

(2) Actuating the confirmation switch S1 of the master station,
Inject the pilot signal into the work line.

At this time, in the pilot signal from the master station 10, the output of the signal generator 23 on the master station side is encoded by the microcomputer 12 and power-amplified by the transmission amplifier 18, and the amplified audio band. Of the pilot signal is injected into the working line short-circuited by the short-circuit device 2 ′ via the transformer 16.

(3) Turn on the main switch of the slave station 11 to operate the slave station 11, and confirm the power supply voltage of the slave station 11.

(4) Input selector switch S3 of slave station 11
Switch to commercial frequency current detection and transformer 1 of slave station 11
6'is attached to all power cables 1 near the work line (at this time, this attachment and detachment can be easily done by making the transformer a split type), the commercial frequency current is measured, and the current Identify the power cable 1 that is not flowing.

At this time, in the slave station 11, the commercial frequency of the signal detected by the transformer 16 'is selectively received by the low-pass filter 30, and the received commercial frequency detection signal is received by the receiving amplifier 14 ". It is input to the A / D converter 15 ″ via the A / D converter, A / D converted, and input to the microcomputer 12 ′. Therefore, the microcomputer 12 'measures the presence or absence and the magnitude of the detected commercial frequency current and displays the result on the display 22'. Therefore, the power cable 1 in which the commercial frequency current does not flow can be specified by reading the display on the display 22 '.

In this way, when the power cable 1 (no-load cable) in which the current of the commercial frequency does not flow can be specified, the input changeover switch S3 of the slave station 11 is switched to the detection of the pilot signal, and the three-phase of the specified power cable 1 is detected. A transformer 16 'is attached to each line, and the pilot signal is confirmed and its level is measured.

That is, the switch S3 for switching between the commercial frequency and the pilot signal is switched to the pilot signal, the bandpass filter 13 'selectively receives the pilot signal, and the received signal is voltage-amplified by the receiving amplifier 14' and A The A / D converter 15 'performs A / D conversion and inputs the result to the microcomputer 12'. The microcomputer 12 'decodes the input signal into a code and displays it on the display 2
Display on 2 '.

At this time, since the displayed data indicates the reception level, the level is calculated and displayed on the display 22 ', for example, by integrating the detected data for a predetermined period.

At this time, when the pilot signal ratio of each phase of the power cable 1 is 2: 1: 1, for example, the display of each cable is 1A: 0.5A: 0.5A, the displayed power of 1A is displayed. Identify cable 1 as the work track.

That is, the measurement level at this time is such that the two ends of the three-phase line are connected in parallel to the one line into which the pilot signal is injected by short-circuiting the separation ends at both ends with the shorting device 2 '. Therefore, the detection level of one line injected with the pilot signal is twice as high as that of the other line,
The ground wire can be easily specified from the measurement result.

In this way, when the largest phase of the pilot signal is specified as the ground-attached phase, the transformer 16 'is attached to that phase, and the automatic grounder 32 is attached.

3. Installation of automatic grounding device (1) Hang the cable fixing belt 35 on the power cable 1 of the grounding mounting phase to which the transformer 16 'of the slave station 11 is fixed,
The automatic grounding device 32 is fixed to the outer cover of the power cable 1 for work. The ground electrode E with a ground wire is attached to the automatic grounding device 32 fixed to the cable 1, and the connection cable is connected to the slave station 11 via the connector 40.

(2) The slave station preparation completion switch S2 is turned on.

When the switch S2 is turned on, the slave station 10
The signal generator 23 'is activated to input the oscillation output to the microcomputer 12', and the oscillation output is used as a carrier.
An encoded output is output corresponding to the ready signal. Then, the encoded output is the transmission amplifier 1
It is amplified by 8'and injected into the working cable 1 via the transformer 16 '.

The ready signal injected into the work cable 1 is received by the master station 10 and detected by the transformer 16 of the master station 10.

The ready signal detected by the transformer 16 of the master station 10 is selectively received by the bandpass filter 13 and amplified by the receiving amplifier 14 to be A /
The digital signal is converted by the D conversion circuit 15 and input to the microcomputer 12. The microcomputer 12 decodes the input signal and displays it on the display 22. Therefore, the work manager of the parent station can visually check the display.
Confirm and operate the confirmation switch S1 to send the operation signal to the slave station 1
Send to 1.

(3) After confirming the operation signal, the slave station 11 sends an operation signal to the automatic grounder 32.

That is, the signal detected by the transformer 16 'attached to the work cable 1 is selectively received by the bandpass filter 13', and the selected and received operation signal is received by the receiving amplifier 14 '. Is voltage-amplified by the A / D converter 15 ', is input to the microcomputer 12' through the A / D converter 15 ', is decoded, and is displayed by the display 22'. Therefore, when the child station worker confirms the display and actuates the preparation completion switch S2, an operation signal is sent to the automatic grounding device 32 via the contact of the relay 31.

(4) On the other hand, when the operation signal from the slave station 11 is input to the automatic grounder 32, the control section 33 operates the drive motor M and advances the ground electrode E. When the ground electrode E comes into contact with the core wire of the power cable 1 with a predetermined pressure, the control unit 33 stops the drive motor M, assuming that the grounding is completed, and sends a stop signal to the slave station 11.

(5) When the slave station 11 receives the stop signal from the automatic grounding device 32, it sends a grounding completion signal to the work cable 1.

That is, in the slave station 11, the automatic grounding device 32
When the stop signal is received, the relay 31 is opened, the signal generator 23 'is activated, the oscillation output is encoded by the microcomputer 12' in accordance with the grounding completion signal, and the encoded grounding completion signal is output. Amplifier for transmission 18 '
It is amplified by and is sent to the work cable 1 by the transformer 16 ′ via the relay 31.

(6) When the master station 10 receives the grounding completion signal from the slave station 11, the grounding work is measured, and then the display 22 indicates that the grounding work is completed.

That is, the signal of the working cable 1 detected by the transformer 16 is selectively received by the bandpass filter of the master station 10, amplified by the receiving amplifier 18, and then the digital signal by the A / D converter 15. Is input to the microcomputer 12. The microcomputer 12 decodes the input signal and displays the completion of grounding on the display 22. Therefore, the parent station side work manager visually checks and confirms the display and informs the slave station side worker.

4. Work start (1) Perform the predetermined cutting work on the work track side.

(2) The master station monitors changes in current due to disconnection and connection of the work line.

(3) When the work cable 1 (signal line) is cut, a new three-phase line short-circuit grounding work is performed on the master station side of the cut portion to secure the operation signal line.

(4) When it is necessary to cut several points by removing the long work cable 1 (signal line), etc., cut from the end portion with respect to the parent station side, and cut the cut portion to the parent station side. A new three-phase short-circuit work will be carried out to secure the operation signal line.

5. End of work (1) Operate the operation switch S4 of the automatic grounder 32 to remove the automatic grounder 32 from the power cable 1.

(2) Complete the predetermined work on the work track side.

(3) Short circuit device 2'for work line, master station 10,
The slave station 11 and the automatic grounding device 32 are removed.

At this time, the microcomputer 12 of the slave station 11 determines the completion status of the work. This completes the series of grounding work.

As described above in detail, in the present invention, all the operations are sequentially controlled by the microcomputer 12, the result is displayed on the display 22 and the operator visually confirms the operation, and then the operation is advanced step by step. For,
The worker and the microcomputer 12 can perform the grounding work while confirming the safety, and the safer and more reliable grounding work can be performed.

Further, since the life and death of the power cable 1 is determined by using the pilot signal in the audio band, the work cable 1 can be specified without being influenced by the guidance of the adjacent power cable 1. At this time, for example, even if the power cable receives the induction from the external magnetic field, the three-phase line will have the same signal level, so in the unlikely event that there are mixed power cables that have the same induction failure as the signal frequency. But it can be clearly distinguished from the working cable. Therefore, this method is an extremely effective means for discriminating the signal current from the external induction received by the power cable itself.

When performing grounding work according to the present invention, when one cable has a plurality of work sites, an automatic grounder is attached to the same ground line to ground at multiple points by the pulse radar method. You can check. In this case, if the three-phase shorting device has the characteristic impedance of the cable, unnecessary reflection does not occur, so that a more accurate grounding point can be determined.

In the embodiment, the transformer 1 of the slave station 11 is used.
Although 6'is provided in the slave station 11, the present invention is not limited to this, and the transformer 16 'may be provided in the automatic grounder 34 as shown in FIG.

In the embodiment, in the automatic grounder,
Although a motor is used to press-fit the ground electrode into the power cable, the invention is not limited to this, and an electric drill, an air drill, an air press, an explosive press, an oil pressure, a solenoid, a spring, etc. are used. You may do it.

[0099]

The invention according to claim 1 of the present invention is configured as described above, and the separated ends of the three-phase lines of the power cable separated from the power system are respectively short-circuited by a short-circuit tool, and the short-circuited three-phase lines are connected. Injecting a pilot signal for discrimination into the grounding line, measuring the current or voltage level in the commercial frequency band of each line to identify the power cable, and for each phase of the identified three-phase line. When the transformers are installed in sequence, the measured value of the pilot signal for discrimination is
When the work cable is identified by using the commercial frequency and the pilot signal by performing the method in which the doubled one is used as the ground wire, when a large induction noise is generated from the power cable around the work cable. But it's definitely a choice. In addition, since the grounding wire is selected step by step according to the above procedure, the grounding work can be performed more safely and surely.

In the invention according to claim 2, by using the invention according to claim 1, a signal for confirmation is exchanged between the master station and the slave station, work is carried out step by step, and safety confirmation is carried out. Since the grounding work is performed while doing so, it is possible to provide an automatic grounding device that can safely ground the work cable.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment.

FIG. 2 is an explanatory view of the operation of the embodiment.

FIG. 3 is a perspective view of a transformer according to an embodiment.

FIG. 4 is a front view of automatic grounding according to the embodiment.

FIG. 5 is a sectional view of a slide mechanism according to an embodiment.

FIG. 6 is a diagram for explaining another grounding confirmation method.

FIG. 7 is an operation explanatory view showing a conventional grounding method.

[Explanation of symbols]

 1 Power Cable 2'Short Circuit Device 10 Master Station 11 Slave Station 12, 12 'Microcomputer 13, 13' Bandpass Filter 14, 14 ', 14 "Receiver Amplifier 15, 15', 15" A / D Converter 16, 16 'Transformer 17, 17' Reception circuit 18, 18 'Transmission amplifier 19, 19' Transmission circuit 20, 20 'Lamp 21, 21' Buzzer 22, 22 'LCD display 23, 23' Signal generator 30 Low-pass filter 32 Auto grounder 33 Control unit 34 Auto grounder body M Drive motor E Ground electrode S1 Confirmation switch S2 Ready switch S3 Changeover switch S4 Operation switch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Masuda 1 Calum Sakai C-201 2-136, Sanpaku-cho, Sakai-shi (72) Inventor Masaki Ikeda 2 City Park 227 Takamatsu, Sakai 823 Kitanoda 823

Claims (2)

[Claims] 1. A method for discriminating a cable separated from a power system, wherein the cable is extracted from a plurality of cables such as a manhole and a switchyard, and grounding is performed, and the power separated from the power system is used. The separated ends of the three-phase line of the cable are respectively short-circuited by a short-circuiting device, and a pilot signal for discrimination is injected into one line that serves as the ground line of the short-circuited three-phase line, and the construction section including the short-circuited three-phase line is injected. Attach a transformer to each line, measure the current or voltage level in the commercial frequency band of each line, detect that the current or voltage is not measured, and then attach the transformer for each phase of the three-phase line in order. This is a method of determining a ground cable in which the pilot signal for determination is measured and the measured value is twice as large as the other measured value as the ground wire. 2. An automatic grounding device for grounding an electric power cable by using the method for discriminating a grounding cable according to claim 1, comprising: a master station for injecting a pilot signal current into the power cable; It consists of a slave station that detects the pilot signal current injected into the cable, drives the automatic grounder, and attaches the ground wire to the power cable, and the master station is a transformer that is attached to the power cable,
Master station side communication means for transmitting and receiving a preparation completion signal, an operation signal, and a grounding completion signal between the pilot signal generating means for injecting a discrimination pilot signal into the power cable through the transformer and the slave station. And an operation switch for transmitting an operation signal to the master station side communication means, and an informing means for informing the data received by the communication means, while the slave station is of a clamp type attachable to a power cable. A transformer, monitoring means for monitoring the presence or absence of commercial frequency current flowing through the power cable through the transformer attached to the power cable, and a pilot signal transmitted by the power cable from the master station through the transformer. Detecting means for detecting, a notifying means for notifying the level of the pilot signal detected by the detecting means, a preparation completion signal between the master station, an operation signal, A slave station side communication means for transmitting and receiving a grounding completion signal, a confirmation switch for transmitting a preparation completion signal to the slave station side communication means, a reporting means for reporting data received by the slave station side communication means, and the automatic grounding And a grounding means for bringing the grounding electrode connected to the grounding wire into contact with the center conductor of the cable by the advancing mechanism of the automatic grounding device connected to the working switch of the slave station. An automatic grounding device comprising grounding confirmation means for outputting a grounding confirmation signal to output to the slave station side communication means when the grounding electrode contacts the center conductor of the power cable by the grounding means.