JP2010223906A - Method and device for detecting abnormality of shielding member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost device for detecting abnormality of a shield member aimed at improvement in the detection accuracy. <P>SOLUTION: Both ends of copper tape 13 of a plurality of CV cables 101-103 are connected to each other. By changing a selector switch SW, a current transformer CT1 is connected to an alternating-current power supply 31, to make alternating current flow through the copper tape 13, and current transformers CT2 and CT3 are connected to an FFT waveform analyzer 22. Thus, the FFT waveform analyzer 22 extracts the frequency component of the alternating-current power supply 31 from electromotive force from the current transformers CT2 and CT3, according to the current flowing through the copper tape 13 of the CV cables 102 and 103 and displays it. Next, by changing the selector switch SW, the current transformer CT2 is connected to the alternating-current power supply 31, and the current transformers CT1 and CT3 are connected to the FFT waveform analyzer 22. Then, by changing the selector switch SW, the current transformer CT3 is connected to the alternating-current power supply 31, and the current transformers CT1 and CT2 are connected to the FFT waveform analyzer 22. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a shield member abnormality detection method and a shield member abnormality detection device.

  As an electric wire having the shield member described above, for example, a CV cable 101 for supplying high-voltage power as shown in FIG. 2 is known. As shown in the figure, the CV cable 101 includes a core wire 11, an insulator 12 as an internal insulator, a copper tape 13 as a shield member, and a sheath 14 as an external insulator.

  The core wire 11 is made of a conductive conductor. The insulator 12 is made of crosslinked polyethylene or the like and covers the core wire 11. The copper tape 13 is provided to prevent noise from entering the outside. The copper tape 13 is provided in a tape shape and is wound around the outer periphery of the insulator 12. The sheath 14 is made of polyethylene or the like and covers the copper tape 13.

  The above-mentioned hot wire deterioration diagnosis of the water tree of the CV cable 101 is shifting from the DC leakage current measurement to the AC superimposition deterioration diagnosis measurement. For this reason, since the direct current leakage current measurement which needs a terminal process is not performed, the deterioration condition of the copper tape 13 of the terminal part of CV cable 10 cannot be confirmed directly, but only the visual inspection from the outside is performed. Is the situation.

  However, in the CV cable 101, abnormalities such as displacement of the copper tape 13 and corrosion breakage may occur due to shrinkage due to aging. Thereby, there existed a problem that the performance quality of the CV cable 10 deteriorated.

  Therefore, for example, a rupture inspection circuit for supplying a DC voltage to the copper tape 13 and measuring the resistance value of the copper tape 13 and detecting the rupture of the copper tape 13 based on the measured resistance value of the copper tape 13 has been proposed. (Patent Document 1). Further, when a DC voltage is applied to the measurement end of the copper tape 13 via the detection resistor, and the DC voltage is stepped up or down from the reference value to a predetermined value, the current flowing through the detection resistor and both ends of the detection resistor There has been proposed a deterioration detection method for discriminating the deterioration state of the copper tape 13 from the relationship with the voltage generated in the above (Patent Document 2).

  However, there may be many noises such as DC stray current at the measurement site. In the conventional break inspection circuit and deterioration detection method described above, a DC power source is supplied to the copper tape 13. For this reason, the resistance value cannot be accurately measured under the influence of the DC stray current. In addition, since the current flowing through the detection resistor and the voltage generated at both ends of the detection resistor fluctuate under the influence of the DC stray current, there is a problem that the abnormality of the copper tape 13 cannot be detected accurately.

JP 2002-214273 A JP 2003-240816 A

  Therefore, an object of the present invention is to provide a shield member abnormality detection method and an abnormality detection device that improve detection accuracy at a low cost.

  The invention according to claim 1, which has been made to solve the above-mentioned problems, includes a conductive core wire, an internal insulator covering the core wire, a shield member wound around an outer periphery of the internal insulator, and the shield member A shield member abnormality detecting method for detecting an abnormality of the shield member in a plurality of wires in which both ends of the shield member are connected to each other. A first step of flowing an alternating current through the member, a second step of detecting a current flowing through the shield member of each of the wires, and an alternating current of the detected current flowing through the shield member in the first step. A third step of extracting a frequency component, and a fourth step of detecting an abnormality of the shield member based on the magnitude of the extracted frequency component of the alternating current If, it consists in the abnormality detecting method of the shield member, characterized in that sequentially performed.

  According to a second aspect of the present invention, in the first step, an alternating current from an alternating current power source is supplied to one of a plurality of coils provided for each shield member of the electric wire to generate a magnetic field in the coil. An alternating current is passed through the shield member by a magnetic field, and in the second step, an electromotive force generated in the remaining coils to which the alternating current is not supplied among the plurality of coils is detected as a current flowing through the shield member of the wire. The present invention resides in the abnormality detection method for a shield member according to claim 1.

  The invention according to claim 3 has a conductive core wire, an internal insulator covering the core wire, a shield member wound around the outer periphery of the internal insulator, and an external insulator covering the shield member. In the abnormality detection device for a shield member that detects a failure of the shield member in a plurality of electric wires that are connected to each other at both ends of the shield member, an alternating current for causing an alternating current to flow through the shield member of the wire A power supply, a plurality of current detection means for detecting current flowing in the shield member of each electric wire, and a frequency extraction means for extracting a frequency component of the AC power supply from the current detected by the current detection means. It exists in the abnormality detection apparatus of the shield member characterized by the above-mentioned.

  The invention according to claim 4 further comprises an abnormality detection means for detecting an abnormality of the shield member based on the magnitude of the frequency component of the AC power source extracted by the frequency extraction means. 3. The abnormality detection device for a shield member according to 3.

  The invention according to claim 5 is configured such that each of the plurality of current detection means is a coil that generates an electromotive force according to the current value when a current flows through the shield member of each electric wire, An AC current is supplied to a coil constituting one of a plurality of current detection means, a magnetic field is generated in the coil, and an AC current is supplied to the copper tape by the magnetic field. It exists in the abnormality detection apparatus of the shield member of 3 or 4.

  As described above, according to the first and third aspects of the invention, the alternating current is supplied to the shield member, and the frequency component of the alternating current power source is extracted from the current flowing through the shield member, so that it is separated from the stray current. The detection accuracy can be improved. In addition, since an alternating current is supplied to the shield member, the alternating current may be a low pressure and an abnormality can be detected safely.

  According to the second and fourth aspects of the present invention, the function of flowing an alternating current through the shield member and the function of detecting the current flowing through the shield member can be shared by a single coil. There is no need to separately attach the power source to the shield member, the apparatus becomes easy, and the cost can be reduced.

  According to invention of Claim 5, abnormality of a shield member can be detected by the abnormality detection means.

It is a block diagram which shows one Embodiment of the abnormality detection apparatus of the shield member of this invention. It is sectional drawing of the CV cable shown in FIG. It is a perspective view which shows the detail of the current transformer shown in FIG. It is a perspective view which shows other embodiment of the current transformer shown in FIG.

  Hereinafter, the abnormality detection apparatus for the copper tape 13 (shield member) of the present invention will be described with reference to the drawings. The abnormality detection device 20 is a device that detects an abnormality in a plurality of CV cables 101 to 103 composed of R, S, and T phases. As described in the background art, the CV cable 101 includes a core wire 11, an insulator 12 as an internal insulator, a copper tape 13 as a shield member, and a sheath as an external insulator, as shown in FIG. 14.

  The core wire 11 is made of a conductive conductor. The insulator 12 is made of crosslinked polyethylene or the like and covers the core wire 11. The copper tape 13 is provided in a tape shape and is wound around the outer periphery of the insulator 12. The sheath 14 is made of polyethylene or the like and covers the copper tape 13. Here, the abnormality of the copper tape 13 means that the copper tape 13 is displaced or corroded to cause a portion where the copper tape 13 is cut. Since the CV cables 102 and 103 have the same configuration as the CV cable 101, detailed description thereof is omitted here.

  One ends of the copper tapes 13 constituting the plurality of CV cables 101 to 103 are connected to each other and grounded. Further, the other ends of the copper tapes 13 constituting the plurality of CV cables 101 to 103 are connected to each other. That is, each copper tape 13 is connected so as to form three loops.

  Next, the configuration of the abnormality detection device 20 will be described. As shown in FIG. 1, the abnormality detection device 20 includes current transformers CT1 to CT3 as current detection means, a changeover switch SW, an AC power supply 31, and an FFT waveform analysis device 22 as frequency extraction means. ing. The current transformers CT1 to CT3 are provided one for each of the CV cables 101 to 103. As shown in FIG. 3, the current transformer CT <b> 1 includes a pair of coils 211, a bobbin 212, and a core 213. The pair of coils 211 is disposed in the vicinity of the copper tape 13 of the CV cable 101. For this reason, when an alternating current flows through the copper tape 13, an alternating magnetic field is generated around the copper tape 13. When the AC magnetic field passes through the pair of coils 211, an electromotive force is generated at both ends of the pair of coils 211. This electromotive force has a value corresponding to the alternating current flowing through the copper tape 13. When an alternating current is supplied to the pair of coils 211, an alternating magnetic field passing through the coil 211 is generated. The alternating current flows through the copper tape 13 due to electromagnetic induction by the alternating magnetic field.

  The pair of bobbins 212 are provided in a cylindrical shape, and a coil 211 is wound around the outer peripheral surface thereof. The core 213 is made of a magnetic material and is provided in a quadrangular ring shape. A pair of bobbins 212 are inserted into a pair of opposite sides of the quadrangular annular core 213, respectively. The copper tape 13 of the CV cable 101 passes through the center of the quadrangular annular core 213. The core 213 can collect magnetic fields generated when an alternating current flows through the copper tape 13, thereby improving the current detection accuracy of the coil 211. Further, a magnetic field generated when an alternating current is passed through the coil 211 by the core 213 can be collected and a larger alternating current can be passed through the copper tape 13. Since the current transformers CT2 and CT3 have the same configuration as the current transformer CT1, a detailed description thereof is omitted here.

  The changeover switch SW is a switch for switching the connection between both ends of the coil 211 between an AC power supply 31 described later and the FFT waveform analysis device 22. The AC power supply 31 supplies an AC current to the connected coil 211 when both ends of the coil 211 are connected by the changeover switch SW. When the alternating current from the alternating current power supply 31 is supplied to the coil 211, the alternating current flows through the copper tape 13 as described above. When an alternating current flows through the copper tape 13, superimposed currents I <b> 1 to I <b> 3 flow through the three loops formed on the copper tape 13, respectively.

  The FFT waveform analyzer 22 is connected to both ends of the coil 211 by the changeover switch SW, and is supplied with an electromotive force according to the alternating current flowing through the copper tape 13 generated at both ends of the coil 211. The FFT waveform analysis device 22 sequentially performs fast Fourier transform (FFT) on the electromotive force, extracts the frequency components of the AC power supply 31 from the electromotive force, and displays them.

  Next, the detection principle of the abnormality detection device 20 configured as described above will be described. When the copper tape 13 is normal, three loops are formed in the copper tape 13 as described above. For this reason, for example, when an alternating current from the alternating current power supply 31 is passed through the coil 211 of the current transformer CT1, superimposed currents I1 to I3 having a frequency component of the alternating current power supply 31 flow through the copper tape 13. Now, for example, as shown by x in FIG. 1, when the copper tape 13 of the CV cable 103 at the bottom of the drawing is cut, the copper tape 13 of the CV cable 10 in which the copper tape 13 is cut is generated. No current flows in the. Therefore, no electromotive force is generated in the coil 211 of the current transformer CT3 provided on the copper tape 13 of the CV cable 103 in which the copper tape 13 is broken.

  Therefore, if the frequency component of the AC power supply 31 displayed by the FFT waveform analysis device 22 is approximately 0, the inspector can determine that the copper tape 13 is abnormal. On the other hand, if the magnitude of the frequency component of the AC power supply 31 displayed by the FFT waveform analyzer 22 is equal to or greater than the threshold value, the inspector can determine that the copper tape 13 is normal.

  Next, the procedure of the abnormality detection method using the above-described abnormality detection device 20 will be described. First, the inspector operates the changeover switch SW to connect both ends of the coil 211 of the current transformer CT1 to the AC power supply 31 and to connect both ends of the coils 211 of the current transformers CT2 and CT3 to the FFT waveform analyzer 22. To do. Thereby, an alternating current flows through the copper tape 13 due to the magnetic field generated in the coil 211 of the current transformer CT1, and superimposed currents I1 through I3 flow through the three loops formed in the copper tape 13, respectively. Next, the current transformer CT <b> 2 generates an electromotive force corresponding to the current flowing through the copper tape 13 of the CV cable 102, and outputs the electromotive force to the FFT waveform analyzer 22. The current transformer CT3 generates an electromotive force corresponding to the current flowing through the copper tape 13 of the CV cable 103, and outputs the electromotive force to the FFT waveform analysis device 22. The FFT waveform analyzer 22 displays the magnitude of the frequency component of the AC power supply 31 by sequentially performing fast Fourier transform on the electromotive force supplied from the current transformers CT2 and CT3. The inspector looks at the frequency component of the AC power supply 31 displayed on the FFT waveform analyzer 22 and determines whether or not an abnormality has occurred in the copper tape 13 of the CV cables 102 and 103.

  Next, the inspector operates the changeover switch SW to connect both ends of the coil 211 of the current transformer CT2 to the AC power supply 31 and to connect the both ends of the coils 211 of the current transformers CT1 and CT3 to the FFT waveform analyzer 22. Similarly, the frequency component of the AC power supply 31 displayed on the FFT waveform analyzer 22 is similarly viewed, and it is determined whether or not an abnormality has occurred in the copper tape 13 of the CV cables 101 and 103. Thereafter, the inspector operates the changeover switch SW to connect both ends of the coil 211 of the current transformer CT3 to the AC power supply 31 and to connect both ends of the coils 211 of the current transformers CT1 and CT2 to the FFT waveform forming device 22. Similarly, by looking at the frequency component of the AC power supply 31 displayed on the FFT waveform analyzer 22, it is determined whether or not an abnormality has occurred in the copper tape 13 of the CV cables 101 and 102.

  According to the abnormality detection device 20 described above, an alternating current is supplied to the copper tape 13 and the frequency component of the alternating current power supply 31 is extracted from the current flowing through the copper tape 13, so that it can be separated from the stray current. The accuracy can be improved.

  In addition, according to the abnormality detection device 20 described above, the current detection unit is configured by the coil 211 that generates an electromotive force according to the current value when a current flows through the copper tape 13 of each of the CV cables 101 to 013. The power supply 31 supplies an alternating current to one of the coils 211 provided for each of the copper tapes 13 of the CV cables 101 to 103 to generate a magnetic field in the coil 211 and cause the alternating current to flow by the magnetic field. Provided. For this reason, since the function of flowing an alternating current through the copper tape 13 and the function of detecting the current flowing through the copper tape 13 can be combined with one coil 211, the apparatus becomes easy and the cost can be reduced. it can.

  Further, according to the abnormality detection device 20 described above, all of the current transformers CT <b> 1 to CT <b> 3 are sequentially connected to the AC power supply 31. And every time it connects, the electromotive force which generate | occur | produces in remaining current transformer CT1-CT3 which is not connected to AC power supply 31 is supplied to the FFT waveform analysis apparatus 22, and the abnormality of the copper tape 13 of the CV cables 101-103 is detected is doing. Thereby, the electromotive force generated in each of the current transformers CT1 to CT3 is supplied to the FFT waveform analyzer 22 twice. That is, the abnormality of the copper tape 13 can be detected twice for each of the CV cables 101 to 103, and the abnormality of the copper tape 13 can be reliably detected.

  In addition, in embodiment mentioned above, although core 213 was provided in current transformer CT1-CT3, this invention is not limited to this. For example, as illustrated in FIG. 4, a configuration in which the current transformers CT <b> 1 to CT <b> 3 are configured by the coil 211 and the bobbin 212 without providing the core 213 and the copper tape 13 is passed through the coil 211 is also conceivable. .

  In the above-described embodiment, the current transformers CT1 to CT3 are sequentially connected to the AC power supply 31, and the electromotive force generated in the current transformers CT1 to CT3 is supplied to the FFT waveform analyzer 22 twice each. However, the present invention is not limited to this. For example, two of the current transformers CT1 to CT3 are sequentially connected to the AC power supply 31, and the electromotive force generated in the current transformers CT1 to CT3 is supplied to the FFT waveform analysis device 22 once each to the copper tape. You may detect 13 abnormalities.

  In the above-described embodiment, only the frequency component of the AC power supply 31 is displayed by the FFT waveform analysis device 22, but the present invention is not limited to this. For example, the frequency component of the AC power supply 31 extracted by the FFT waveform analysis device 22 is supplied to an abnormality detection device as an abnormality detection means configured by a microcomputer or the like, and the abnormality detection device is supplied from the FFT waveform analysis device 22. You may make it determine whether abnormality has arisen in the copper tape 13 based on the magnitude | size of the frequency component of the alternating current power supply 31. FIG. As an example, for example, the abnormality detection device may determine that an abnormality has occurred in the copper tape 13 if the magnitude of the frequency component of the AC power supply 31 supplied from the FFT waveform analysis device 22 is equal to or less than a threshold value. .

  Further, the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

10 CV cable (electric wire)
11 Core wire 12 Insulator (Internal insulator)
13 Copper tape (shield member)
14 Sheath (external insulator)
22 FFT waveform analyzer (frequency extraction means)
31 AC power supply 211 Coil CT1 to CT3 Current transformer (current detection means)

Claims (5)

A plurality of electric wires having a conductive core wire, an internal insulator covering the core wire, a shield member wound around an outer periphery of the internal insulator, and an external insulator covering the shield member, In the shielding member abnormality detection method for detecting abnormality of the shielding member in a plurality of electric wires in which both ends of the shielding member are connected to each other,
A first step of passing an alternating current through the shield member of the wire;
A second step of detecting a current flowing through the shield member of each electric wire,
A third step of extracting the frequency component of the alternating current flowing through the shield member in the first step from the detected current;
A fourth step of detecting an abnormality of the shield member based on the magnitude of the extracted frequency component of the alternating current;
A method for detecting an abnormality of a shield member, characterized in that the steps are sequentially performed. In the first step, an alternating current from an alternating current power source is supplied to one of a plurality of coils provided for each shield member of the electric wire to generate a magnetic field in the coil, and the alternating current is applied to the shield member by the magnetic field. Shed
The electromotive force which generate | occur | produces in the remaining coil to which the said alternating current is not supplied among these coils in the said 2nd process is detected as an electric current which flows into the shield member of the said electric wire. Shield member abnormality detection method. A plurality of electric wires having a conductive core wire, an internal insulator covering the core wire, a shield member wound around an outer periphery of the internal insulator, and an external insulator covering the shield member, In the abnormality detection device for a shield member that detects abnormality of the shield member in a plurality of electric wires in which both ends of the shield member are connected to each other,
An alternating current power source for passing an alternating current through the shield member of the wire;
A plurality of current detection means for detecting currents flowing in the shield members of the electric wires;
A frequency extracting means for extracting a frequency component of the AC power source from the current detected by the current detecting means;
An apparatus for detecting an abnormality of a shield member, comprising: The abnormality detection of the shield member according to claim 3, further comprising an abnormality detection means for detecting an abnormality of the shield member based on the magnitude of the frequency component of the AC power source extracted by the frequency extraction means. apparatus. Each of the plurality of current detection means is composed of a coil that generates an electromotive force according to the current value when a current flows through the shield member of each electric wire,
The AC power supply is provided so as to supply an AC current to a coil constituting one of the plurality of current detection means, generate a magnetic field in the coil, and cause the AC current to flow through the copper tape by the magnetic field. The abnormality detection device for a shield member according to claim 3 or 4,

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