JP2001141770A - Detecting method of shield tape disconnection of high- tension cable, detector for shield tape disconnection, and judgment device for shield tape disconnection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detecting method and device for shield tape disconnection of high-tension cable capable of regularly detecting the disconnection of the shield tape wire of a leading-in cable in a non-contact manner. SOLUTION: This device comprises a superposing CT 10 for injecting a measuring monitoring voltage to the shield tape 3S of the leading-in cable 3 in a non-contact manner and current detectors 11, 12 and 13 for detecting the current in no contact every shield tape 3R, 3T and 3S. In this device, a shield tape disconnection judgment device 15 compares the detection current from each current detector 11, 12 or 13 with a preset reference current while transmitting a monitor signal of a prescribed frequency different from commercial power by use of the superposing CT 10 and judges and reports the disconnection of each shield tape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for connecting a breakage of a shield tape of a drop-in cable for drawing in transformed power between a power distribution side (a power receiving facility of a distribution line) and a private substation. The present invention relates to a high-voltage cable shield tape disconnection detection method, a shield tape disconnection detection device line, and a shield tape disconnection determination device that can be easily detected without any modification.

[0002]

2. Description of the Related Art As shown in FIG. 4, a high voltage (for example, 20,000 V) from a transmission line (R-phase, S-phase, T-phase) of an off-site power company.
Is temporarily received by a power receiving facility 1 provided on a service pole or the like, and is transformed to about 6600 V, and is transmitted to a private substation facility 2 on the premises by a service cable 3 which is a high-voltage cable. In general, the drop cable 3 has an inner semiconductive layer formed around a core wire 3a as a conductor, an insulator made of cross-linked polyethylene or the like formed outside the outer semiconductive layer, and an outer semiconductive layer formed outside the outer semiconductive layer. A shielding tape 3b made of a shielding copper tape is formed outside the outer semiconductive layer, and an insulating layer such as a vinyl sheath is formed on the outermost layer.

[0003] This shield tape 3b is, for example, corrosion,
Anomalies may occur due to mechanical strength, trauma, etc. In this case, discharge may occur at an abnormal location, which is a serious problem such as direct connection to an electrical breakdown accident.

An apparatus for detecting such an abnormality of the shield tape 3b is a single-core cable shielding abnormality monitoring apparatus disclosed in Japanese Patent Publication No. 6-14086.

As shown in FIG. 5, this single-core cable shielding abnormality monitoring device comprises a shielding tape 5R for each phase of the cable 5.
An abnormal voltage detection and notification device 6 for connecting these shielding tapes collectively to downstream ends of 5S and 5T and detecting an abnormal voltage of the shielding tape is provided.

[0006] In addition, shielding ground changeover switches 7R, 7S, 7T are provided at the upstream end of each of the shielding tapes 5R, 5S, 5T.
T is provided, and these shield ground changeover switches are normally closed contacts, one is connected to each shielding tape, and the other is grounded.

The normally closed contact of the shield / ground changeover switch has a capacitance 8, a resistor 9, and an arrester connected in parallel collectively.

In the single-core cable shielding abnormality monitoring device configured as described above, the abnormal voltage detection / alarm device 6 includes the shielding tape 5.
When an abnormal voltage of R, 5S, 5T is detected, or
Shielding ground changeover switches 7R, 7 at any timing
S, 7T is switched, and accordingly, the resistance meter 9 changes the shielding tape 5
The resistance values of R, 5S, and 5T were measured to determine whether the state was abnormal.

As another example, a downstream end of the shielding tape is collectively connected and grounded as in a method for detecting an abnormality of the shielding tape disclosed in Japanese Patent Application Laid-Open No. Sho 58-106473 shown in FIG. There is a method of providing a current transformer.

[0010] An alarm is connected to this current transformer, and an alarm is issued in the event of an abnormal accident, thereby recognizing an abnormal state.

[0011]

However, the single-core cable shielding abnormality monitoring device described above measures the resistance value when detecting an abnormal voltage or at an arbitrary timing.
Only at that point is it determined whether there is any abnormality.

It is important to recognize the occurrence of a single-core cable abnormality as soon as possible, and with the above method, it is not expected to be very effective in preventing an accident before an abnormality is determined. On the contrary, since the shielded ground changeover switch, which is a switch having a contact, is used, a contact abnormality may occur due to some reason such as lapse of time, and an unexpected accident other than an abnormality such as a fire may occur.

Further, when this device is used for an existing drop cable, construction for interrupting the device is required.
In addition, it is necessary to perform work that is easy to check the state of the connection part, and it takes time and labor, so there is a problem that power transmission is stopped for a long time, and after the start of operation, the connection part changes over time or suddenly There was a problem that it was necessary to continue to check for abnormalities.

In the method for detecting a shielding tape abnormality described later, since both ends of the lead-in cable are grounded, a stray current flows and a circulating current flows between the shielding tapes of each phase, which makes accurate measurement difficult. There's a problem. However, if the end of the incoming cable without a current transformer is opened, a loop circuit cannot be formed and measurement cannot be performed.

Therefore, it is desirable that the shield tape can be constantly monitored without contact.

[0016]

A first aspect of the present invention is a method for detecting disconnection of a shield tape of a high-voltage lead-in cable for connecting a power receiving facility for supplying commercial power and a private substation facility. , Three or more single-core cables having a shield tape are bundled, and the end of the shield tape on the side of the power receiving equipment is connected to a ground wire via a lead wire after the end treatment, and then collectively grounded. Connect the end of the shield tape on the side of the private substation equipment via a terminating resistor with a predetermined resistance value, and inject a measuring alternative voltage into one of the shield tapes of the high-voltage drop-in cable in a non-contact manner. The gist of the present invention is to detect a current in a non-contact manner every time, and to determine a break in the shield tape from the detected current and a preset reference current.

A second aspect of the present invention is a high-voltage drop cable for connecting a power receiving facility for supplying commercial power to a private substation facility, wherein the high-pressure drop cable is a bundle of three or more single-core cables having a shield tape. Yes, the power receiving equipment side end of the shield tape is connected to a ground line via a lead wire after each end processing, and then collectively grounded,
Any phase of the lead wire on the high-voltage drop cable side from the collective ground connection point, penetrate it, and attach a transformer that supplies an alternative voltage for measurement to the shield tape without performing the connection work, and At the same time, the lead wires of the other phases are pierced through them and in the same opposite position as the transformer,
The current transformers that detect the current generated as a result of supplying the alternative voltage for measurement to the transformer are attached to each other without performing the wiring work, and are used as the non-injection phase. A current transformer is also mounted between the transformer tapes without performing a wiring operation, and the end of the shield tape on the side of the private substation is connected to the injection phase and each of the non-injection phases in a one-to-one manner by a terminating resistor having the same predetermined resistance. That is the gist.

A third aspect of the present invention is a shield tape wire disconnection detecting device for detecting the disconnection of a shield tape of a high voltage service cable for connecting a power receiving facility for supplying commercial power to a private substation facility. The power receiving equipment side end is connected to a ground wire via a lead wire after the end treatment, and then collectively grounded, and the private transformer equipment side end of the shield tape is passed through a terminating resistor having a predetermined resistance value. A transformer which is connected to any of the leads and which injects an alternative voltage for measurement into the lead without contact, and a current flowing through the lead for each lead of the drop cable. A non-contact current detector for detecting,
The gist of the present invention is to compare a detected current from a current transformer with a reference current value set to a predetermined value while supplying alternative power for measurement to a transformer, and to notify the presence or absence of a break in the shield tape from the comparison result.

According to a fourth aspect of the present invention, in the third aspect, the detected current value uses an effective component excluding the capacitance of the monitoring system, and can be constantly monitored and measured without being influenced by the cable length. And

According to a fifth aspect of the present invention, in the fourth aspect, the active component is obtained by causing the transformer to supply a measurement alternative power different from the commercial power, and extracting the measurement alternative power component from the detection current from the current transformer. The gist is that it is a detected current value.

A sixth aspect of the present invention is based on the first, second, or third aspect, wherein the sum of the resistance values of the terminating resistors is set to be substantially the same as the ground resistance at the end of the power receiving facility.

A seventh aspect of the present invention is based on the first, second, or third aspect, wherein the sum of the resistance values of the terminating resistors is 100 to 300Ω.

An eighth aspect of the present invention is characterized in that, in the third aspect, the current transformer is a zero-phase current transformer.

A ninth aspect of the present invention is a device for determining the breakage of a shield tape of a high-voltage service cable for connecting a power receiving facility for supplying commercial power and a private substation, wherein the high-voltage service cable has an end on the power receiving facility side. After the end treatment, each is connected to a ground line via a lead wire, then collectively grounded, and the private transformer side end of the shield tape is connected via a terminating resistor having a predetermined resistance value. And a transformer which is provided on any one of the lead lines and injects a measuring alternative voltage into the lead line in a non-contact manner, and a non-contact current detection for detecting a current flowing through the lead line for each lead line A power supply means for measurement for supplying a substitute power for measurement different from commercial power to the transformer, and an extraction means for extracting a substitute power component for measurement from a detected current from the current transformer. A reference current value set in the detected current value with a predetermined value constantly monitored and compared to the gist that a discriminating means for notifying to determine the presence or absence of disconnection of the shielding tape from the comparison result.

According to a tenth aspect, in the ninth aspect, the reference current is connected to a resistance of the shield itself and one end of the shield tape when the shield tape of the drop cable induces a voltage of a predetermined frequency in a normal state. The point is that the current value flows through the resistor.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram of a method and an apparatus for detecting a disconnection of a shield tape of a high-voltage cable according to the present invention. This shield tape disconnection detection device is a non-contact monitoring signal (= alternative voltage for measurement) to the S-phase shield tape 3S of the lead-in cable 3 for drawing in three phases of high voltage (6600 V) from the power receiving equipment 1 to the private substation equipment 2. ) Vs. the current flowing through the R-phase shield tape 3R and the T-phase shield tape 3T via the terminating resistors (Ra, Rb) inserted between SR and ST of these shield tapes. The change and the S-phase shield tape 3S are continuously and continuously detected in a non-contact manner.

Based on the detected current, disconnection of the R-phase shield tape 3R, the S-phase shield tape 3S, and the T-phase shield tape 3T is monitored and determined.

The R-phase shield tape 3R, the S-phase shield tape 3S, and the T-phase shield tape 3T of the drop-in cable 3 are connected to the upstream side of the power receiving facility 1 (power distribution side).
Are drawn out from the terminal processing section at the end of each shield tape, and after passing through an arbitrary length, are collectively connected to a ground line to be collectively grounded.

Further, in the conventional method, the side of the private substation equipment 2 which is on the downstream side is opened for the purpose of preventing the inflow of stray current into the shield tape and the generation of the circulating current between the shield tapes. In this case, a terminating resistor is provided in this portion. One end of the terminating resistor Ra is connected to the S-phase shield tape 3S, and the other end is connected to the R-phase shield tape 3R.

The terminating resistor Rb has one end connected to the S-phase shield tape 3S and the other end connected to the T-phase shield tape 3S.
T.

The terminating resistors Ra and Rb have the same resistance. Thereby, between S-R, S-T
A loop circuit can be created between them, and measurement by the current transformer becomes possible, and even if the shield tape breaks, the load side shield tape passes through the terminating resistor and the remaining phase shield tape. Since the shield tape is grounded, an increase in the potential of the broken portion of the shield tape can be suppressed to a range that does not cause damage to the cable.

It is desirable that the sum of the resistance values is substantially the same as the resistance value of the grounding system, and in the embodiment of the present invention, is set to be approximately between 100 and 300Ω (in the present invention, for example, It is desirable to use 50Ω), thereby effectively suppressing generation of a circulating current and sufficiently restricting a voltage induced across the terminating resistor when the shield tape is disconnected.

A predetermined frequency is applied to the shield tape 3S in a non-contact (electromagnetic coupling) manner by a penetrating magnetic core between the S-phase shield tape 3S and the collective ground line connection portion of the lead wires drawn out from the S-phase shield tape. Supplies a predetermined voltage (predetermined electric power) at a time, and superimposes C to induce a current is monitoring signal vs.
T10 (non-contact type transformer) is provided.

At the same position as the R-phase shield tape 3R, the T-phase shield tape 3T, or the superimposed CT 10 of the lead wire drawn therefrom, an R-phase shield tape generated by the action of the superimposed CT is provided. 3R, the current ir flowing through the T-phase shield tape 3T,
Current detectors (current transformers) 11 and 12 which are non-contact type and are penetrating magnetic cores for detecting the current. Further, a lead-out line between the superimposed CT 10 and the shield tape 3S has a penetration type magnetic core for detecting a current is flowing through the S-phase shield tape 3S and is a non-contact type current detector (current transformer). ) 10a is also provided.

The currents ir, it and is detected by the current detectors 11, 12 and 10a are sent to a shield tape disconnection judging device 15 which will be described later. The shield tape disconnection determination device 15 includes a power supply unit that supplies alternative power for measurement to the superimposed CT 10, and current detectors 11, 12, 10a.
An input unit that receives a detection current from the input unit, a comparison unit that compares a detection current value at the time of constant monitoring with a predetermined reference current value set in advance or a normal detection current value and compares the presence or absence of breakage, based on a result of the comparison unit. A display unit for performing an alarm, a display, and the like when there is a disconnection is provided.

The shield tape disconnection judging device 15 compares the magnitudes of the detected currents ir, it, and is or compares them with a predetermined reference current value (both are resistance value conversion comparisons) to detect the R-phase shield tape. Monitoring is constantly performed to determine whether any one of the 3R and S-phase shield tapes 3S and the T-phase shield tape 3T is broken or a plurality of broken wires. Although the details of the determination of the disconnection will be described later, in the present invention, when the cable constant length is short, the detection current ir,
It and is are used as signals, and when the cable length is long, the effective component ior of the detection current ir, it, is to remove the influence of the capacitance between the three cables.
iot and ios are used as signals.

More specifically, the detection currents ir, it,
is is input as a signal to the shield tape disconnection determination device 15, and despite the fact that there is a phase error due to the influence of the capacitance between the cables and the impedance of the transformer / current transformer or the disconnection, the capacitance at the capacitance portion As a result of intensive research, we found that the accuracy of detection was further improved by performing processing to remove errors due to the resistance value of the shield tape itself that would affect erroneous detection due to short-circuits and that would affect long cable lengths. Therefore, in the present invention, obtaining the effective current value and using it as a signal for determining disconnection is the most desirable specification in the disconnection determination apparatus for the shield tape disconnection detection method of the present invention.

If the R-phase shield tape 3R breaks, ir or ior decreases, and if the T-phase shield tape 3T breaks, it or i
ot decreases.

When the S-phase shield tape 3S is broken, ir and it or ior and iot decrease simultaneously. Using this, it is possible to specify whether or not the shield tape is disconnected and the phase of the disconnection. Further, when a plurality of shield tapes are disconnected, for example, when the S phase and the R phase are disconnected,
ir and is or ior and ios decrease simultaneously, and i
If t or iot increases, and the R phase and the T phase are disconnected, ir and it or ior and iot are simultaneously reduced, and is or ios is increased.

Since the detected current decreases when the shield tape is disconnected, the predetermined reference value or the value of the normal detection current is stored in memory, and the detected current value when the disconnection is detected is determined by the predetermined reference value or the normal detection current. In addition to the detection of the disconnection phase, it is also possible to specify at which part of the entire cable length the disconnection has occurred, based on the numerical value obtained by dividing by the above value.

The current detectors 11, 12, and 10a transmit voltage signals obtained by converting the detected currents ir, it, and is to resistance.
5, the monitoring signal vs is injected by the supply voltage from the power supply unit, but in the present embodiment, the same symbols are used to facilitate understanding.

FIG. 2 is a schematic configuration diagram of the shield tape disconnection judging device 15. Shield tape disconnection determination device 15
As shown in FIG. 2, a DA converter 16, a signal generation circuit 17, a power amplification circuit 18, and a phase adjustment circuit 19
, Amplifiers 21, 22, 23 and bandpass filter 2
4, 25, 26 and detection circuits (DET) 27, 28, 2
9, AD converters 30, 31, 32, and a computer unit 33.

The DA converter 16 is connected to the computer 3
3 every time current value data is output (every 1 msec)
Then, the data is converted to analog. That is, 1KH
Send out a square wave of z.

The signal generation circuit 17 includes a DA converter 16
A power signal obtained by converting a 1 KHz rectangular current signal into a sine wave from the power supply circuit 18 is sent to the power amplification circuit 18, and a 1 KHz sine wave measurement alternative voltage Vs is applied from the superimposed CT 10 to the S-phase shield tape 3 </ b> S. A current (hereinafter referred to as a monitoring signal is) is injected.

The reason why the monitoring signal is is set to 1 KHz is to prevent interference with a 50 Hz or 60 Hz current flowing through the core wire.

Here, the description of the superimposed CT10 will be supplemented. The superimposed CT 10 serves as a power supply unit for injecting a measuring alternative power different from the commercial frequency in a non-contact manner, and generally supplies a measuring alternative voltage to a single-point grounding type ground wire.

The configuration is such that a plurality of exciting coils are wound on the primary side, and a voltage is induced on the grounding line by using the grounding wire of the insulated monitoring electric circuit penetrating through the window as a once-turned secondary conductor. Things.

The phase adjustment circuit 18 receives the current signal generated by the signal generation circuit 17 and changes the phase of the current signal.
It is adjusted in consideration of the phase error due to the capacitance, resistance and the like of the drop cable 3 and sent out to the detection circuits 27, 28 and 29.

On the other hand, the amplifier 21 is a shield tape 3R
Is connected to the output terminal of the non-contact current detector 11 provided in the drop-in line, and the detection current ir is input, amplified, and transmitted to the band-pass filter 24.

The amplifier 22 is connected to the output terminal of the non-contact current detector 12 provided on the lead-in line connected to the shield tape 3T.
The signal is sent to the band pass filter 25.

The amplifier 23 includes a non-contact current detector 13 (Z) provided on a drop-in line connected to the shield tape 3S.
CT3), the detection current is input, amplified, and sent to the band-pass filter 26.

The band pass filters 24, 25, 26
Only the detection currents ir, it, and 1 s of 1 KHz are passed. That is, only the 1 KHz current is extracted.

The detection circuit 27 includes a band-pass filter 24
Current i of the lead wire of the R-phase shield tape 3R from the
r and the phase adjusted current io from the phase adjustment circuit 19
, And detects the component of the detection current ir synchronized (phased) with the current io, and sends out the detected component to the AD converter 30.

The detection circuit 28 includes a band-pass filter 25
Current i of the drop wire of the T-phase shield tape 3T from
t and the phase adjusted current io from the phase adjustment circuit 19
And detects the component of the detection current it synchronized with the current io, and sends the detected component to the AD converter 31.

The detection circuit 29 includes a band-pass filter 26
Current i of the lead-in wire of the S-phase shield tape 3S from
s and the phase-adjusted current io from the phase adjustment circuit 19
, And detects a component of the detection current is synchronized with the current io, and sends the detected component to the AD converter 31.

The AD converters 30, 31 and 32 convert the detected detection currents ir, it and is into digital signals and send them to the computer 33.

The computer section 33 detects the detection currents ir, i
t, is input and a preset reference current ip
(Current flowing through the terminating resistors Ra and Rb when the shield tapes 3R, 3S, and 3T are normal) is compared with the disconnection of the shield tapes 3R, 3S, and 3T, and the result is notified by an LED or the like.

The above-described signal generation circuit 17, DA converter 16, power amplification circuit 18, and phase adjustment circuit 19 are collectively referred to as a signal generation section, and include amplification circuits 21, 22, 23 and band-pass filters 24, 25, 26. And the detection circuits 27 and 2
8, 29 and the AD converters 30, 31, 32 are collectively referred to as a detected current extracting unit.

The operation of the shield tape disconnection judging device 15 configured as described above will be described with reference to the flowchart of FIG.

First, the shield tape disconnection judging device 15
Causes the DA converter 16 to inject a 1 KHz sine wave measurement monitoring voltage Vs into the shield tape 3S for the superimposed CT 10 via the signal generation circuit 17 and the power amplification circuit 18 every 1 msec (S301).

That is, the current Is flowing due to the application of the measurement monitoring voltage Vs flows through the shield tape 3S as shown in FIG. 1, flows through the shield tape 3R via the terminating resistor Ra (current ir), and terminates. The current flows through the shield tape 3T via the resistor Rb (current it).

Then, the non-contact current detectors 11, 12,
13 detects currents ir, it, and is flowing through the shield tapes 3R, 3T, 3S, are amplified by the amplifier circuits 21, 22, 23, respectively, and are detected by the detection circuits 27, 28 via the band-pass filters 24, 25, 26. , 29
Sent to

The detection circuits 27, 28 and 29 extract components synchronized with the phase-adjusted current signal Io from the phase adjustment circuit 19 and send them to the computer 33 via the AD converters 30, 31 and 32. I do. In other words, only the effective component based on the monitoring voltage for measurement Vs is extracted in consideration of the phase error due to the phase rotation due to the shield tape, the capacitance, the terminating resistance and the like.

Each time the detected currents ir, it, and is from the AD converters 30, 31, and 32 are written to the input port, the computer unit 33 outputs the current values ir and i.
t and is are read into the internal memory (S303), and the current values ir, it and is are determined (S305).

In step S305, the detected current ir
When it is determined that the (current of the R-phase shield tape) is equal to or less than the reference current ip stored in advance, it is determined that the R-phase shield tape 3R is disconnected (S307), and the R-phase shield tape 3R is disconnected. An LED for damage notification is displayed (S309).

When it is determined in step S305 that the detected current it (current of the T-phase shield tape) is equal to or less than the previously stored reference current ip, it is determined that the T-phase shield tape 3T is disconnected. (S311), T
An LED for reporting the damage of the phase shield tape 3T is displayed (S313).

Further, in step S305, when both the detected current ir and the detected current it are determined to be equal to or less than the reference current ip, or when the detected current is determined to be equal to or less than the reference current ip, the S-phase shield tape 3S Is determined to be disconnected (S317), and the S-phase shield tape 3
The LED for reporting the damage of T is displayed.

In step S305, the detected current i
When it is determined that r, the detection currents it and is equal to or higher than the reference current, it is determined that the shield tapes 3R, 3S and 3T are normal (S319).

The explanation about the above-mentioned reference current ip is supplemented.

For example, when each shield tape is normal, the monitoring voltage Vr (voltage E
When o) is injected, the currents ir and it flowing through the shield tapes 3R and 3T become

(Equation 1)

(Equation 2) Squeezed.

The current i at the normal time represented by the equations (1) and (2)
r, it, and is stored in advance as the reference current ip of each shield tape.

Then, the aforementioned steps S309 and S31
After the processes of 3, 317 and 319, the process returns to the process of step S303 to return to the current i flowing through the shield tapes 3R and 3T.
Continue monitoring r, it, and is.

That is, the contactless current detector 11,
Just attach the 12,13 and non-contact superimposed CT10 to the shield tape 3R, 3S, 3T of the drop-in cable,
Since the breakage of the shield tape of each phase can be detected, there is no need to take any action on the drop cable 3.

Although the monitoring voltage for measurement is injected into the S-phase shield tape 3S in the above embodiment, it may be injected into the R-phase shield tape or the T-phase shield tape.

Further, each shield tape is provided with a superimposed CT and a non-contact current detector, and a switching means for switching a phase to be injected into the shield tape disconnection determination device is provided.
If necessary, a monitoring voltage for measurement may be injected into the shield tape 3R, 3T, or 3S.

Further, it may be determined which part of the shield tape is broken according to the amount of the detected currents is, ir, it.

[0077]

As described above, according to the disconnection detecting method of the present invention, the monitoring voltage for measurement is injected in a non-contact manner into any one of the shield tapes of the drop-in cable, and the current flowing through each shield tape is non-contact. Detection is performed by contact, and the detected current is compared with a preset reference current to determine and notify the disconnection of each shield tape.

For this reason, an effect is obtained that the disconnection of the shield tape can always be detected in a non-contact manner without any modification to the lead-in cable.

Further, according to the present invention, a drop-in wire is provided on each shield tape of the drop-in cable, a monitoring voltage for measurement is injected into the drop-in wire of any of these shield tapes in a non-contact manner, and a current flowing through each shield tape is measured. Non-contact detection is performed at the drop-in line, and these detected currents are compared with a preset reference current to determine and notify the disconnection of each shield tape.

For this reason, an effect is obtained that disconnection of the shield tape can be easily detected without contact at all times.

Further, according to the apparatus for detecting disconnection of the shield tape of the present invention, the end of the cable on the power receiving facility side is connected to the ground line via the lead wire after the end processing, and then the grounding processing is performed collectively. For the incoming cable connected via a terminating resistor with a predetermined resistance, provide a drop wire to each shield tape and connect the end of the shield tape on the side of the private substation equipment to the drop wire of any of these shield tapes without contact. A monitoring voltage for measurement is injected with a measuring device, and a current flowing through each shield tape is detected by a current detector in a non-contact manner at a lead-in line, and these detected currents are compared with a preset reference current to compare each shield tape. And notify the disconnection.

For this reason, there is an effect that disconnection of the shield tape can be easily detected without contact at all times.

Further, since one end of each shield tape is commonly connected via a resistor, the current injected into the shield tape is diverted to another shield tape via the resistor. The effect is that the value can be easily determined.

Further, according to the shield tape disconnection judging device, a current signal having a frequency different from the commercial power is injected from the non-contact current transformer provided in the lead-in cable into the shield tape, and the other shield tapes are used. The detected current is read, and when the detected current is detected to be equal to or less than the reference current, the shield tape that has obtained the detected current determines that the wire is broken and informs it.

For this reason, a non-contact current transformer and a non-contact current detector are attached to the shield tape of the drop-in cable, and the shield tape can always be monitored in a non-contact manner simply by connecting to the shield tape disconnection determination device. Have been obtained.

Each time a current is injected into the shield tape, a current signal whose phase has been adjusted based on the capacitance of the drop cable, the resistance of the shield itself, and the resistance connected to one end of the shield tape is generated. Since the disconnection determination is made for the current of only the synchronous component between the signal and the detection current of the other shield tape, the effect that the disconnection can be determined using the true detection current based on the current injected into the shield tape is obtained. I have.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a shield tape disconnection detection system according to the present embodiment.

FIG. 2 is a schematic configuration diagram of a shield tape disconnection determination device according to the present embodiment.

FIG. 3 is a flowchart illustrating an operation of the shield tape disconnection determination device according to the present embodiment.

FIG. 4 shows a state where a drop-in cable of a private substation is not attached.

FIG. 5 is a configuration diagram of a conventional single-core cable shielding damage monitoring device.

FIG. 6 is a configuration diagram of a method of detecting a copper tape break in a cable of the prior application.

[Explanation of symbols]

 3, incoming cable 3S, 3R, 3T shield tape 10 superimposed CT 11 non-contact detector 12 non-contact detector 15 shield tape disconnection determination device 17 signal generation circuit 18 power amplification circuit 19 phase adjustment circuit 27, 28, 29 detection circuit

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[Procedure amendment]

[Submission date] November 25, 1999 (1999.11.
25)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroki Nakajima 4-1-8 Konan, Minato-ku, Tokyo Asahi Engineering Co., Ltd. (72) Inventor Hiroshi Sase 1-5-1 Kiba, Koto-ku, Tokyo Inside Fujikura (72) Inventor Hirowa Kiyomi 1-5-1 Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (72) Hajime Suzuki 5-4-2 Hiroo, Shibuya-ku, Tokyo Midori Safety Co., Ltd. F-term (Reference) 2G014 AA02 AB31 AC07 2G015 AA27 BA00 CA00

Claims (10)

[Claims] 1. A method for detecting disconnection of a shield tape of a high-voltage service cable for connecting a power receiving facility for supplying commercial power and a private substation facility, wherein the high-voltage service cable includes a single-core cable having a shield tape. After the end of the shield tape, the end of the shield tape is connected to a ground line via a lead wire, and then collectively grounded, and the end of the shield tape is connected to a private substation facility. Is connected via a terminating resistor having a predetermined resistance value, and a non-contact alternative voltage for measurement is injected into any of the shield tapes of the high-voltage pull-in cable, and a current is detected in a non-contact manner for each shield tape. Determining the disconnection of the shield tape from the detected current and a preset reference current. Detection method. 2. A high-voltage drop cable for connecting a power receiving facility for supplying commercial power and a private substation facility, wherein the high-pressure drop cable is a bundle of three or more single-core cables having a shield tape. The end of the shield tape on the side of the power receiving equipment is connected to a ground line via a lead after being subjected to the end treatment, and then collectively grounded, and any phase of the lead wire on the high-voltage lead-in cable side from a collective ground connection point. In this case, a transformer for supplying an alternative voltage for measurement to the shield tape is passed through it, and the transformer is attached without performing the connection work to make it the injection phase, and the lead wires of the other phases are passed through it. At the same opposing position as the transformer, current transformers for detecting the current generated as a result of supplying the alternative voltage for measurement to the transformer are installed without any wiring work to make the non-injection phase. A current transformer is also mounted between the transformer of the high-voltage drop cable as a phase and the shield tape without performing connection work, and the end of the shield tape on the side of the private substation equipment is the injection phase and the non-injection phases. Are connected by a terminating resistor having the same predetermined resistance value on a one-to-one basis. 3. An apparatus for detecting disconnection of a shield tape of a high-voltage service cable for connecting a power receiving facility for supplying commercial power and a private substation facility, wherein the high-voltage service cable has an end on the power receiving facility side. After each part is connected to a ground line via a lead wire, then collectively grounded, and the private transformer side end of the shield tape, is connected via a terminating resistor of a predetermined resistance value, A transformer that is provided on any one of the outgoing lines and that injects an alternative voltage for measurement into the outgoing line in a non-contact manner; and for each outgoing line of the incoming cable, a non-contact type that detects a current flowing through the outgoing line. A current detector for comparing the detected current from the current transformer with a reference current value set to a predetermined value while supplying alternative power for measurement to the transformer; Shielding tape breakage detecting device high-voltage cables, characterized in that it comprises a shield table disconnection determination unit for notifying the presence or absence of disconnection of the flop. 4. The method according to claim 3, wherein the detected current value is:
A shielded tape breakage detection device for a high-voltage cable, characterized by being able to monitor and measure at all times without being influenced by the cable length, using an effective component excluding the capacitance of the monitoring system. 5. The alternative power component for measurement according to claim 4, wherein the active component causes the transformer to supply an alternative power for measurement different from the commercial power, and uses a detection current from the current transformer to detect the alternative power component. A detection device for detecting a break in a shielded tape of a high-voltage cable, wherein the detection current value is a detection current value obtained by extracting a current. 6. The method according to claim 1, wherein the sum of the resistance values of the terminating resistors is set to be substantially the same as the grounding resistance at the end of the power receiving facility. And a disconnection detection device using the same. 7. A method for detecting a disconnection of a shield tape of a high-voltage cable according to claim 1, wherein the sum of the resistance values of the terminating resistors is 100 to 300Ω. . 8. The apparatus according to claim 3, wherein the current transformer is a zero-phase current transformer. 9. A device for judging a break of a shield tape of a high-voltage service cable for connecting a power receiving facility for supplying commercial power to a private substation facility, wherein the high-voltage service cable has an end on the power receiving facility side of the cable. After connecting the parts, each is connected to a ground line via a lead wire, then collectively grounded, and the private transformer side end of the shield tape is connected via a terminating resistor having a predetermined resistance value, And a transformer which is provided on any one of the lead wires and injects a measuring alternative voltage into the lead wire in a non-contact manner, and a non-contact current for detecting a current flowing through the lead wire for each of the lead wires. A detector is provided, a measuring power supply unit that supplies a measuring alternative power different from the commercial power to the transformer, and extracting the measuring alternative power component from a detection current from the current transformer. Extracting means, and a determining means for constantly monitoring and comparing the extracted detected current value and a reference current value set to a predetermined value, and determining and notifying whether or not the shield tape is disconnected based on the comparison result. A shield tape disconnection determination device for a high-voltage cable, comprising: 10. The method according to claim 9, wherein the reference current is:
When the voltage of the predetermined frequency is induced in a normal state with the shield tape of the drop-in cable, a current flowing through the resistance of the shield itself and the resistance connected to one end of the shield tape is set. Shield tape disconnection determination device.