JP2013019710A - Coated cable surface dirt detection device - Google Patents

Coated cable surface dirt detection device Download PDF

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JP2013019710A
JP2013019710A JP2011151440A JP2011151440A JP2013019710A JP 2013019710 A JP2013019710 A JP 2013019710A JP 2011151440 A JP2011151440 A JP 2011151440A JP 2011151440 A JP2011151440 A JP 2011151440A JP 2013019710 A JP2013019710 A JP 2013019710A
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voltage
detection
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electric wire
covered electric
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JP5693404B2 (en
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Koichi Yanagisawa
浩一 柳沢
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Hioki EE Corp
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Hioki EE Corp
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PROBLEM TO BE SOLVED: To obtain a downsized and low-cost device without requiring a power source generating a large current.SOLUTION: A coated cable surface dirt detection device comprises: an injection electrode 2 that is capacitively coupled with a central conductor 12a of a coated cable 12; a detection electrode 3 that is capacitively coupled with the central conductor 12a; an AC voltage generation part 4 that generates test AC voltage V2, and injects the test AC voltage V2 into the central conductor 12a through the injection electrode 2 in a non-contact manner; a current detection part 5 that inputs a portion of current Id2, which is generated in the coated cable 12 by the injection of the test AC voltage V2, through the detection electrode 3, converts the current Id2 into detection voltage Vd and outputs the detection voltage Vd; and a processing part 7 that calculates a ratio k of a voltage value of the detection voltage Vd to a voltage value of the test AC voltage V2, and determines that a surface of the coated cable 12 is dirty when the calculated ratio k is equal to or greater than a predetermined reference ratio kref.

Description

本発明は、被覆電線の表面に生じた汚れ（塵や埃の付着に起因した汚れ）を検出する被覆電線の表面汚れ検出装置に関するものである。   The present invention relates to a surface contamination detection device for a covered electric wire that detects contamination (dirt caused by dust or dust adhesion) generated on the surface of the covered electric wire.

本願発明者は、検出対象体に生じている交流電圧を非接触で検出する各種の電圧検出装置を既に提案している（下記の特許文献１など）。これらの電圧検出装置では、検出対象体に対して検出電極を対向配置することによって、検出対象体と検出電極とを容量結合（静電容量を介して結合）させ、この静電容量を介して検出対象体と検出電極との間に流れる電流に基づいて、検出対象体の交流電圧を検出する。また、特許文献１にも開示されているように、この電圧検出装置は、電路を検査対象体として、電路についての電圧（線間電圧など）も検出することが可能である。   The inventor of the present application has already proposed various voltage detection devices that detect the AC voltage generated in the detection object in a non-contact manner (Patent Document 1 below). In these voltage detection devices, a detection electrode and a detection electrode are disposed opposite to a detection target body to capacitively couple the detection target body and the detection electrode (coupled via a capacitance). Based on the current flowing between the detection object and the detection electrode, the AC voltage of the detection object is detected. In addition, as disclosed in Patent Document 1, this voltage detection apparatus can also detect a voltage (such as a line voltage) for an electric circuit using the electric circuit as an inspection object.

しかしながら、電路（通常は、被覆電線で構成される）の表面に塵や埃が付着して汚れの層が形成され、この汚れの層が水分を含んで導電性を帯びる状態に至ることがある。この状態では、電路の芯線（中心導体）と電圧検出装置の検出電極との間に、導電性を有する汚れの層が介在することになるため、結合容量を介して電路の芯線と電圧検出装置の検出電極との間に流れる電流の一部が、この汚れの層を介して漏れ出る結果、検出対象体としての電路の芯線に生じる交流電圧の測定精度が低下するという改善すべき課題が存在している。   However, dust or dirt adheres to the surface of an electric circuit (usually composed of a covered electric wire) to form a dirt layer, and this dirt layer may contain water and become conductive. . In this state, since a conductive dirt layer is interposed between the core wire (center conductor) of the electric circuit and the detection electrode of the voltage detection device, the core wire of the electric circuit and the voltage detection device are connected via a coupling capacitor. As a result, a part of the current flowing between the detection electrode and the detection electrode leaks through this dirt layer, and as a result, there is a problem to be solved that the measurement accuracy of the AC voltage generated on the core of the electric circuit as the detection target is lowered. doing.

この課題を改善するため、電圧検出に先立ち、例えば下記の特許文献２に開示されている非接触式表面抵抗測定装置を使用して、検出対象体の表面に汚れの層が形成されているか否かを検出する構成を採用することもできる。   In order to improve this problem, prior to voltage detection, for example, using a non-contact type surface resistance measuring device disclosed in Patent Document 2 below, whether or not a dirt layer is formed on the surface of the detection object. It is also possible to adopt a configuration for detecting this.

特開２０１１−５３２０１号公報（第１４−１５頁、第１図）Japanese Patent Laying-Open No. 2011-53201 (pages 14-15, FIG. 1) 特開２００３−８４０２０号公報（第４頁、第１図）JP 2003-84020 A (page 4, FIG. 1)

しかしながら、この非接触式表面抵抗測定装置を使用する構成には、以下のような解決すべき課題が存在している。すなわち、この非接触式表面抵抗測定装置では、フェライトコイルなどのコイルで渦電流発生部を構成し、このコイルに交流波電圧を印加し、コイルを導電膜（表面抵抗を測定するもの）に近づけることで、導電膜に高周波誘導結合による渦電流を流している。しかしながら、高周波誘導結合によって渦電流を流し得るようにするためには、一般的に、コイルに大きな電流を流す必要が生じる。このため、この非接触式表面抵抗測定装置には、大きな電流を発生させる電源が必要になり、装置が大型化すると共に装置コストが上昇するという解決すべき課題が存在していいる。   However, the configuration using this non-contact type surface resistance measuring device has the following problems to be solved. That is, in this non-contact type surface resistance measuring device, a coil such as a ferrite coil constitutes an eddy current generator, an AC wave voltage is applied to this coil, and the coil is brought close to a conductive film (for measuring surface resistance). Thus, an eddy current due to high frequency inductive coupling is passed through the conductive film. However, in order to allow an eddy current to flow by high-frequency inductive coupling, it is generally necessary to flow a large current through the coil. For this reason, this non-contact type surface resistance measuring apparatus requires a power source that generates a large current, and there is a problem to be solved that the apparatus becomes larger and the apparatus cost increases.

本発明は、かかる課題を解決すべくなされたものであり、大きな電流を発生させる電源を不要として、装置の小型化および低コスト化を図り得る被覆電線の表面汚れ検出装置を提供することを主目的とする。   SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and it is an object of the present invention to provide a coated wire surface contamination detection device that can reduce the size and cost of the device without requiring a power source that generates a large current. Objective.

上記目的を達成すべく請求項１記載の被覆電線の表面汚れ検出装置は、被覆電線の中心導体と容量結合する注入電極と、前記中心導体と容量結合する検出電極と、検査交流電圧を生成すると共に当該検査交流電圧を前記注入電極を介して前記中心導体に非接触で注入する交流電圧生成部と、前記検査交流電圧の注入に起因して前記被覆電線に発生する電流の一部を前記検出電極を介して入力すると共に検出電圧に変換して出力する電流検出部と、前記検査交流電圧の電圧値に対する前記検出電圧の電圧値の比率を算出すると共に当該算出した比率が予め決められた基準比率以上のときに、前記被覆電線の表面が汚れていると判別する処理部とを備えている。   In order to achieve the above object, a device for detecting surface contamination of a covered electric wire according to claim 1 generates an inspection AC voltage, an injection electrode capacitively coupled to a central conductor of the covered electric wire, a detection electrode capacitively coupled to the central conductor. And an AC voltage generator for injecting the inspection AC voltage to the central conductor through the injection electrode in a non-contact manner, and detecting a part of the current generated in the covered electric wire due to the injection of the inspection AC voltage. A current detection unit that inputs through the electrodes and converts the detection voltage to output, and calculates a ratio of the voltage value of the detection voltage to the voltage value of the inspection AC voltage, and the calculated ratio is a predetermined reference And a processing unit that determines that the surface of the covered electric wire is dirty when the ratio is equal to or greater than the ratio.

また、請求項２記載の被覆電線の表面汚れ検出装置は、請求項１記載の被覆電線の表面汚れ検出装置ポンプ回路において、前記被覆電線の表面が汚れていると前記処理部によって判別されたときにその旨を出力する出力部を備えている。   Further, the coated wire surface contamination detection device according to claim 2 is a pump circuit of the coated wire surface contamination detection device according to claim 1, wherein the processing unit determines that the surface of the coated wire is dirty. Is provided with an output section for outputting the fact.

請求項１記載の被覆電線の表面汚れ検出装置によれば、生成した検査交流電圧を注入電極を介して被覆電線の中心導体に非接触で注入する交流電圧生成部と、検査交流電圧の注入に起因して被覆電線の表面の汚れの層を介して流れる電流の一部を検出電極を介して入力する電流検出部とを備えて、被覆電線の表面の汚れを検出するため、渦電流発生用の大きな電流を発生させる電源を不要にすることができる結果、装置の小型化および低コスト化を図ることができる。   According to the apparatus for detecting surface contamination of a covered electric wire according to claim 1, an AC voltage generating unit that injects the generated inspection AC voltage into the central conductor of the covered electric wire through an injection electrode in a non-contact manner, and injection of the inspection AC voltage For detecting eddy currents on the surface of the covered wire, the current detection unit inputs a part of the current that flows through the dirty layer on the surface of the covered wire through the detection electrode. As a result, it is possible to reduce the size and cost of the apparatus.

請求項２記載の被覆電線の表面汚れ検出装置によれば、被覆電線の表面が汚れているときに、出力部がその旨を出力するため、被覆電線の表面が汚れていることを確実に把握することができる。   According to the surface dirt detection device for a covered electric wire according to claim 2, when the surface of the covered electric wire is dirty, the output unit outputs that fact, so that the surface of the covered electric wire is reliably grasped. can do.

検出装置１の構成図である。1 is a configuration diagram of a detection device 1. FIG. 被覆電線１２の表面に汚れの層１３が形成されていない状態での検出装置１の動作を説明するための説明図である。It is explanatory drawing for demonstrating operation | movement of the detection apparatus 1 in the state in which the dirt layer 13 is not formed in the surface of the covered electric wire 12. FIG. 被覆電線１２の表面に汚れの層１３が形成されている状態での検出装置１の動作を説明するための説明図である。It is explanatory drawing for demonstrating operation | movement of the detection apparatus 1 in the state in which the layer 13 of dirt is formed in the surface of the covered electric wire 12. FIG.

以下、被覆電線の表面汚れ検出装置の実施の形態について、添付図面を参照して説明する。   Hereinafter, an embodiment of a device for detecting surface contamination of a covered electric wire will be described with reference to the accompanying drawings.

最初に、被覆電線の表面汚れ検出装置１（以下、「検出装置１」ともいう）の構成について、図面を参照して説明する。   First, the structure of the surface dirt detection device 1 (hereinafter also referred to as “detection device 1”) of the covered electric wire will be described with reference to the drawings.

検出装置１は、図１に示すように、注入電極２、検出電極３、交流電圧生成部４、電流検出部５、Ａ／Ｄ変換部６、処理部７および出力部８を備え、商用電源１１から出力された商用電圧Ｖａｃを伝送するための被覆電線１２の表面が汚れているか否かを非接触で検出する。被覆電線１２は、一例として、商用電圧Ｖａｃを伝送する中心導体１２ａ、および絶縁被覆１２ｂを備えている。   As shown in FIG. 1, the detection device 1 includes an injection electrode 2, a detection electrode 3, an AC voltage generation unit 4, a current detection unit 5, an A / D conversion unit 6, a processing unit 7, and an output unit 8. Whether or not the surface of the covered electric wire 12 for transmitting the commercial voltage Vac output from 11 is dirty is detected without contact. As an example, the covered electric wire 12 includes a central conductor 12a that transmits the commercial voltage Vac and an insulating coating 12b.

注入電極２および検出電極３は、被覆電線１２に対向して非接触の状態で配設されて、中心導体１２ａとそれぞれ容量結合する。   The injection electrode 2 and the detection electrode 3 are disposed in a non-contact state facing the covered electric wire 12 and are capacitively coupled to the center conductor 12a.

交流電圧生成部４は、電圧生成回路４ａおよび電圧増幅回路４ｂを備えている。電圧生成回路４ａは、予め規定された電圧値（振幅）であって、商用電圧Ｖａｃの周波数（商用周波数）とは異なる周波数（例えば商用周波数を超える周波数）の交流電圧Ｖ１を生成する。電圧増幅回路４ｂは、交流電圧Ｖ１を所定の増幅率で増幅して検査交流電圧Ｖ２として注入電極２に出力する。この構成により、交流電圧生成部４は、生成した既知の電圧値（振幅）の検査交流電圧Ｖ２を注入電極２を介して被覆電線１２の中心導体１２ａに非接触で注入する。   The AC voltage generation unit 4 includes a voltage generation circuit 4a and a voltage amplification circuit 4b. The voltage generation circuit 4a generates an AC voltage V1 having a voltage value (amplitude) defined in advance and having a frequency (for example, a frequency exceeding the commercial frequency) different from the frequency (commercial frequency) of the commercial voltage Vac. The voltage amplification circuit 4b amplifies the AC voltage V1 with a predetermined amplification factor and outputs the amplified voltage to the injection electrode 2 as the inspection AC voltage V2. With this configuration, the AC voltage generator 4 injects the generated test AC voltage V2 having a known voltage value (amplitude) into the central conductor 12a of the covered wire 12 through the injection electrode 2 in a non-contact manner.

電流検出部５は、信号増幅回路５ａおよび検波回路５ｂを備えている。信号増幅回路５ａは、一例として電流電圧変換回路で構成されて、種々の要因で被覆電線１２に発生する電流Ｉのうちの検出電極３を介して入力する電流Ｉｄを検出電圧Ｖｉに変換して出力する。この場合、この電流Ｉｄは、例えば、中心導体１２ａで伝送される商用電圧Ｖａｃ、および外来ノイズによって中心導体１２ａに誘起されるノイズ電圧に起因して生じる電流Ｉｄ１と、交流電圧生成部４から出力される検査交流電圧Ｖ２のうちの中心導体１２ａに注入される検査交流電圧Ｖ２および被覆電線１２の表面（絶縁被覆１２ｂの表面）に汚れの層１３（図３参照）が存在しているときにはこの層１３に注入される検査交流電圧Ｖ２に起因して生じる電流Ｉｄ２との合成電流となる。   The current detection unit 5 includes a signal amplification circuit 5a and a detection circuit 5b. The signal amplifying circuit 5a is configured by a current-voltage conversion circuit as an example, and converts the current Id input through the detection electrode 3 out of the current I generated in the covered wire 12 due to various factors into the detection voltage Vi. Output. In this case, the current Id is output from, for example, the commercial voltage Vac transmitted through the center conductor 12a, the current Id1 caused by the noise voltage induced in the center conductor 12a due to external noise, and the AC voltage generator 4. The inspection AC voltage V2 injected into the central conductor 12a of the inspection AC voltage V2 and the surface of the covered electric wire 12 (surface of the insulation coating 12b) are present when the dirt layer 13 (see FIG. 3) is present. This is a combined current with the current Id2 generated due to the inspection AC voltage V2 injected into the layer 13.

検波回路５ｂは、同期検波回路として構成されて、検出電圧Ｖｉを交流電圧Ｖ１に同期して検波することにより、検出電圧Ｖｉに含まれている電圧のうちから、ノイズや商用電圧Ｖａｃに起因して発生する電流Ｉｄ１に基づく電圧Ｖｉ１を除去すると共に、交流電圧生成部４による検査交流電圧Ｖ２の中心導体１２ａや汚れの層１３への注入に起因して発生する電流Ｉｄ２に基づく電圧Ｖｉ２のみを検出して、この電圧Ｖｉ２の振幅（電圧値）に応じて電圧値が変化する直流電圧としての検出電圧Ｖｄを出力する。   The detection circuit 5b is configured as a synchronous detection circuit, and detects the detection voltage Vi in synchronization with the AC voltage V1, thereby causing noise or the commercial voltage Vac from among the voltages included in the detection voltage Vi. The voltage Vi1 based on the generated current Id1 is removed, and only the voltage Vi2 based on the current Id2 generated due to the AC voltage generation unit 4 injecting the inspection AC voltage V2 into the central conductor 12a and the dirt layer 13 is obtained. The detection voltage Vd as a DC voltage whose voltage value changes according to the amplitude (voltage value) of the voltage Vi2 is detected.

Ａ／Ｄ変換部６は、検出電圧Ｖｄを予め決められた周期でサンプリングすることにより、検出電圧Ｖｄの電圧値を示す電圧データＤｄを出力する。本例では、検出電圧Ｖｄの電圧値は、上記したように電圧Ｖｉ２の振幅（電圧値）に応じて変化するものであるため、電圧データＤｄは、電流Ｉｄ２の電流値を示すデータでもある。   The A / D conversion unit 6 outputs the voltage data Dd indicating the voltage value of the detection voltage Vd by sampling the detection voltage Vd at a predetermined cycle. In this example, since the voltage value of the detection voltage Vd changes according to the amplitude (voltage value) of the voltage Vi2 as described above, the voltage data Dd is also data indicating the current value of the current Id2.

処理部７は、一例として、ＣＰＵおよびメモリ（いずれも図示せず）を備えて構成されている。また、処理部７は、検査交流電圧Ｖ２の電圧値に対する電圧データＤｄで示される電圧値の比率ｋ（＝Ｖｄ／Ｖ２）に基づいて、被覆電線１２の表面に汚れの層１３が存在するか否か（つまり、被覆電線１２の表面が汚れているか否か）を判別する判別処理を実行する。処理部７のメモリには、既知である検査交流電圧Ｖ２の電圧値（振幅）と、比率ｋについての基準比率ｋｒｅｆとが予め記憶されている。この場合、基準比率ｋｒｅｆとは、被覆電線１２の表面の汚れが許容できる状態のときの最大の比率ｋであり、実験などで予め算出された値である。出力部８は、一例として、液晶ディスプレイなどの表示装置で構成されて、判別処理の結果を画面に文字やマークなどで表示する。   For example, the processing unit 7 includes a CPU and a memory (both not shown). In addition, the processing unit 7 determines whether the dirt layer 13 exists on the surface of the covered electric wire 12 based on the ratio k (= Vd / V2) of the voltage value indicated by the voltage data Dd with respect to the voltage value of the inspection AC voltage V2. A determination process is performed to determine whether or not (that is, whether or not the surface of the covered electric wire 12 is dirty). The memory of the processing unit 7 stores in advance a known voltage value (amplitude) of the test AC voltage V2 and a reference ratio kref for the ratio k. In this case, the reference ratio kref is the maximum ratio k when the surface of the covered electric wire 12 is allowed to be contaminated, and is a value calculated in advance through experiments or the like. For example, the output unit 8 is configured by a display device such as a liquid crystal display, and displays the result of the discrimination process on the screen with characters, marks, and the like.

次いで、検出装置１の動作について、図面を参照して説明する。   Next, the operation of the detection device 1 will be described with reference to the drawings.

まず、図２に示すように、被覆電線１２の表面に汚れの層１３が存在していないときの動作について説明する。   First, as shown in FIG. 2, the operation when the dirt layer 13 is not present on the surface of the covered electric wire 12 will be described.

この場合、注入電極２は、被覆電線１２の中心導体１２ａと静電容量Ｃ１を介して容量結合している。また、検出電極３は、被覆電線１２の中心導体１２ａと静電容量Ｃ２を介して容量結合している。この場合、各静電容量Ｃ１，Ｃ２は、数ｐＦ〜１００ｐＦ程度であるため、交流電圧Ｖ１の周波数を例えば１００ｋＨｚとしても、各電極２，３と中心導体１２ａとの間のインピーダンスは１０数キロΩ以上の高い値となる。一方、中心導体１２ａは、商用電源１１の内部抵抗Ｒを介してグランドに接地されるが、この内部抵抗Ｒの抵抗値は通常高くても数Ω程度であることから、中心導体１２ａとグランドとのインピーダンスも高くても数Ω程度である。   In this case, the injection electrode 2 is capacitively coupled to the central conductor 12a of the covered electric wire 12 via the capacitance C1. Further, the detection electrode 3 is capacitively coupled to the central conductor 12a of the covered electric wire 12 via the electrostatic capacitance C2. In this case, since the electrostatic capacitances C1 and C2 are about several pF to 100 pF, even if the frequency of the AC voltage V1 is set to 100 kHz, for example, the impedance between the electrodes 2 and 3 and the central conductor 12a is several tens of kilometers. High value of Ω or higher. On the other hand, the center conductor 12a is grounded via the internal resistance R of the commercial power supply 11, and since the resistance value of the internal resistance R is usually about several ohms at most, the center conductor 12a and the ground Even if the impedance is high, it is about several ohms.

このため、この状態（汚れの層１３が存在しない状態）では、交流電圧生成部４から注入電極２を介して中心導体１２ａに注入された検査交流電圧Ｖ２に起因して中心導体１２ａに発生する電流Ｉｄ２（交流電圧生成部４から被覆電線１２に流れ込む電流）は、その殆どが電流Ｉｄ１と共に、インピーダンスの低い商用電源１１を介してグランドに流れる。したがって、インピーダンスの高い静電容量Ｃ２を介して中心導体１２ａに接続された電流検出部５への電流Ｉｄ２の入力（破線で示す経路に沿った電流Ｉｄ２の入力）は殆ど発生しない。これにより、電流検出部５から出力される検出電圧Ｖｄの電圧値は極めて低いものとなる。   For this reason, in this state (the state in which the dirt layer 13 is not present), it is generated in the center conductor 12a due to the inspection AC voltage V2 injected into the center conductor 12a from the AC voltage generator 4 through the injection electrode 2. Most of the current Id2 (current flowing into the covered electric wire 12 from the AC voltage generator 4) flows to the ground together with the current Id1 through the commercial power supply 11 having a low impedance. Therefore, the input of the current Id2 (the input of the current Id2 along the path indicated by the broken line) to the current detection unit 5 connected to the center conductor 12a via the high-capacitance capacitance C2 hardly occurs. Thereby, the voltage value of the detection voltage Vd output from the current detection unit 5 is extremely low.

処理部７は、判別処理において、電圧データＤｄで示されるこの検出電圧Ｖｄの電圧値についての検査交流電圧Ｖ２の電圧値に対する比率ｋを算出し、さらに、算出した比率ｋと基準比率ｋｒｅｆとを比較する。この場合、上記したように検出電圧Ｖｄの電圧値が極めて低いため、算出される比率ｋも極めて低い値となり、基準比率ｋｒｅｆ以下となる。したがって、処理部７は、算出した比率ｋと基準比率ｋｒｅｆとの比較の結果、算出した比率ｋが基準比率ｋｒｅｆを下回るため、被覆電線１２の表面の汚れは許容範囲内であると判別する。また、処理部７は、この判別結果を表示装置で構成された出力部８の画面に表示させる。   In the determination process, the processing unit 7 calculates a ratio k of the voltage value of the detection voltage Vd indicated by the voltage data Dd to the voltage value of the test AC voltage V2, and further calculates the calculated ratio k and the reference ratio kref. Compare. In this case, since the voltage value of the detection voltage Vd is extremely low as described above, the calculated ratio k is also extremely low, which is equal to or less than the reference ratio kref. Therefore, as a result of the comparison between the calculated ratio k and the reference ratio kref, the processing unit 7 determines that the dirt on the surface of the covered electric wire 12 is within the allowable range because the calculated ratio k is lower than the reference ratio kref. Further, the processing unit 7 displays the determination result on the screen of the output unit 8 configured by a display device.

次いで、図３に示すように、被覆電線１２の表面に汚れの層１３が存在しているときの動作について説明する。一般的に、汚れの層１３は、大気中の塵や埃が絶縁被覆１２ｂの表面に付着して形成されると共に、大気中の水分（湿気）を含んだ状態となっている。このため、汚れの層１３は、絶縁被覆１２ｂの抵抗値よりも低い抵抗値を示す導体層として機能する。   Next, as shown in FIG. 3, the operation when the dirt layer 13 is present on the surface of the covered electric wire 12 will be described. In general, the dirt layer 13 is formed by adhering dust and dirt in the atmosphere to the surface of the insulating coating 12b and containing moisture (humidity) in the atmosphere. For this reason, the dirt layer 13 functions as a conductor layer having a resistance value lower than that of the insulating coating 12b.

これにより、注入電極２は、汚れの層１３と静電容量Ｃ１ａを介して容量結合し、検出電極３は、汚れの層１３と静電容量Ｃ２ａを介して容量結合する。また、汚れの層１３は、被覆電線１２の中心導体１２ａとの間に形成される分布容量Ｃ３を介して中心導体１２ａと容量結合している。この場合においても、各静電容量Ｃ１ａ，Ｃ２ａは、数ｐＦ〜１００ｐＦ程度であるため、交流電圧Ｖ１の上記の周波数に対して、そのインピーダンスは１０数キロΩ以上の高い値となる。   As a result, the injection electrode 2 is capacitively coupled to the dirt layer 13 via the capacitance C1a, and the detection electrode 3 is capacitively coupled to the dirt layer 13 via the capacitance C2a. Further, the dirt layer 13 is capacitively coupled to the central conductor 12a via a distributed capacitance C3 formed between the coated conductor 12 and the central conductor 12a. Also in this case, since the electrostatic capacitances C1a and C2a are about several pF to 100 pF, the impedance becomes a high value of 10 or more kilo ohms or more with respect to the frequency of the AC voltage V1.

しかしながら、汚れの層１３の方が中心導体１２ａよりも各電極２，３に近い位置に存在しているため、交流電圧生成部４から注入電極２を介しての被覆電線１２への検査交流電圧Ｖ２の注入に起因して静電容量Ｃ１ａに流れる電流Ｉｄ２は、図３に示すように、その一部の電流Ｉｄ２ａが、汚れの層１３および静電容量Ｃ２ａを介して検出電極３から電流検出部５に入力され、他の一部の電流Ｉｄ２ｂが、静電容量Ｃ１ａ、汚れの層１３、分布容量Ｃ３、中心導体１２ａおよび商用電源１１を介して、電流Ｉｄ１と共にグランドに流れる。   However, since the dirt layer 13 exists closer to the electrodes 2 and 3 than the central conductor 12a, the inspection AC voltage from the AC voltage generator 4 to the covered wire 12 through the injection electrode 2 As shown in FIG. 3, a part of the current Id2 flowing through the capacitance C1a due to the injection of V2 is detected from the detection electrode 3 via the dirt layer 13 and the capacitance C2a. The other part of the current Id2b that is input to the unit 5 flows to the ground together with the current Id1 via the electrostatic capacitance C1a, the dirt layer 13, the distributed capacitance C3, the central conductor 12a, and the commercial power supply 11.

また、汚れの層１３の抵抗値が低いほど（被覆電線１２の表面の汚れが酷くなるほど）、注入電極２から静電容量Ｃ１ａを介して汚れの層１３に注入される電流Ｉｄ２ａは増加し、その結果、検出電極３から電流検出部５に入力される電流Ｉｄ２ａの電流値も増加する。なお、分布容量Ｃ３は、各静電容量Ｃ１ａ，Ｃ２ａとほぼ同じ数ｐＦ〜１００ｐＦ程度であるため、交流電圧Ｖ１の上記の周波数に対して、そのインピーダンスは１０数キロΩ以上の高い値となる。このため、分布容量Ｃ３を介して中心導体１２ａに一旦注入された電流Ｉｄ２ｂのうち、再度、分布容量Ｃ３を介して汚れの層１３に伝達され、さらに検出電極３を介して電流検出部５に入力される電流は極めて少ない。したがって、電流検出部５から出力される検出電圧Ｖｄの電圧値は、被覆電線１２の表面の汚れが少なくなれば小さくなり、汚れが多くなれば大きくなる（汚れの程度に応じて変化する）。   Further, as the resistance value of the dirt layer 13 is lower (as the dirt on the surface of the covered wire 12 becomes more severe), the current Id2a injected from the injection electrode 2 into the dirt layer 13 via the capacitance C1a increases. As a result, the current value of the current Id2a input from the detection electrode 3 to the current detection unit 5 also increases. Since the distributed capacitance C3 is about the same number pF to 100 pF as the electrostatic capacitances C1a and C2a, the impedance becomes a high value of 10 or more kilo ohms or more with respect to the above frequency of the AC voltage V1. . Therefore, the current Id2b once injected into the central conductor 12a via the distributed capacitor C3 is transmitted again to the dirt layer 13 via the distributed capacitor C3, and further to the current detector 5 via the detection electrode 3. Very little current is input. Therefore, the voltage value of the detection voltage Vd output from the current detection unit 5 decreases as the surface of the covered wire 12 becomes less dirty, and increases as the contamination increases (changes depending on the degree of contamination).

このため、被覆電線１２の表面の汚れが許容範囲内のときには、算出される比率ｋは基準比率ｋｒｅｆ以下となることから、処理部７は、判別処理において、算出した比率ｋが基準比率ｋｒｅｆ以下であるという結果に基づき、被覆電線１２の表面の汚れは許容範囲内であると判別する。一方、被覆電線１２における表面の汚れが許容範囲を超えるときには、算出される比率ｋは基準比率ｋｒｅｆを上回る状態となることから、処理部７は、判別処理において、算出した比率ｋが基準比率ｋｒｅｆを上回るという結果に基づき、被覆電線１２の表面の汚れは許容範囲外である（被覆電線１２の表面が汚れている）と判別する。また、処理部７は、この判別結果を表示装置で構成された出力部８の画面に表示させる。   For this reason, when the surface dirt of the covered wire 12 is within the allowable range, the calculated ratio k is equal to or less than the reference ratio kref. Therefore, in the determination process, the processing unit 7 determines that the calculated ratio k is equal to or less than the reference ratio kref. Based on the result, it is determined that the surface of the covered electric wire 12 is within the allowable range. On the other hand, when the surface contamination of the covered wire 12 exceeds the allowable range, the calculated ratio k exceeds the reference ratio kref. Therefore, the processing unit 7 determines that the calculated ratio k is the reference ratio kref in the discrimination process. Based on the result of exceeding the above, it is determined that the surface of the covered electric wire 12 is out of the allowable range (the surface of the covered electric wire 12 is dirty). Further, the processing unit 7 displays the determination result on the screen of the output unit 8 configured by a display device.

このように、この検出装置１では、交流電圧生成部４が被覆電線１２の中心導体１２ａと容量結合する注入電極２を介して検査交流電圧Ｖ２を中心導体１２ａに非接触で注入している状態において、被覆電線１２の表面に汚れの層１３が存在しているときには、電流検出部５が、この汚れの層１３に流れる電流Ｉｄ２ａを被覆電線１２の中心導体１２ａと容量結合する検出電極３を介して入力して検出電圧Ｖｄに変換して出力し、処理部７が、この検出電圧Ｖｄを示す電圧データＤｄに基づいて被覆電線１２の表面が汚れているか否かを判別する。   Thus, in this detection device 1, the AC voltage generator 4 injects the inspection AC voltage V2 into the center conductor 12a in a non-contact manner via the injection electrode 2 that is capacitively coupled to the center conductor 12a of the covered electric wire 12. When the dirt layer 13 is present on the surface of the covered wire 12, the current detection unit 5 causes the detection electrode 3 that capacitively couples the current Id <b> 2 a flowing through the dirt layer 13 to the center conductor 12 a of the covered wire 12. The processing unit 7 determines whether or not the surface of the covered electric wire 12 is dirty based on the voltage data Dd indicating the detection voltage Vd.

したがって、この検出装置１によれば、上記の交流電圧生成部４および電流検出部５を備えた構成によって、被覆電線１２の表面の汚れを検出することができるため、渦電流発生用の大きな電流を発生させる電源を不要にすることができる結果、検出装置１の小型化および低コスト化を図ることができる。   Therefore, according to this detection apparatus 1, since the structure including the AC voltage generation unit 4 and the current detection unit 5 described above can detect dirt on the surface of the covered electric wire 12, a large current for generating eddy currents can be detected. As a result, it is possible to reduce the size and cost of the detection apparatus 1.

また、この検出装置１によれば、被覆電線１２の表面が汚れていると処理部７によって判別されたときにその旨を出力する出力部８を備えたことにより、出力部８からの出力に基づいて、被覆電線１２の表面が汚れていることを確実に把握することができる。特に本例では、出力部８を表示装置で構成して、判別結果を画面に表示するようにしたことにより、被覆電線１２の表面が汚れているとの判別結果を目視にて確実に把握することができる。   In addition, according to the detection device 1, when the processing unit 7 determines that the surface of the covered electric wire 12 is dirty, the output unit 8 outputs a message to that effect. Based on this, it is possible to reliably grasp that the surface of the covered electric wire 12 is dirty. In particular, in this example, the output unit 8 is configured by a display device, and the determination result is displayed on the screen, so that the determination result that the surface of the covered wire 12 is dirty can be surely grasped visually. be able to.

なお、上記の検出装置１では、処理部７による判別の結果（汚れの層１３の有無）を出力部８としての液晶ディスプレイなどの表示装置に表示させる構成を採用しているが、出力部８をインジケータやスピーカ（またはブザー）で構成して、光や音で判別結果を出力する構成を採用することもできる。この構成を採用して、被覆電線１２の表面が汚れているときに、インジケータを点灯させたり、スピーカなどを鳴動させることにより、被覆電線１２の表面が汚れていることをオペレータに確実に認識させることができる。また、出力部８を伝送装置で構成して、判別結果を他の装置に伝送する構成を採用することもできる。   The detection device 1 employs a configuration in which the result of determination by the processing unit 7 (presence / absence of the dirt layer 13) is displayed on a display device such as a liquid crystal display as the output unit 8. It is also possible to adopt a configuration in which an indicator or speaker (or buzzer) is used to output a discrimination result with light or sound. By adopting this configuration, when the surface of the covered electric wire 12 is dirty, the operator can reliably recognize that the surface of the covered electric wire 12 is dirty by turning on an indicator or ringing a speaker or the like. be able to. In addition, a configuration in which the output unit 8 is configured by a transmission device and the determination result is transmitted to another device may be employed.

１ 検出装置
２ 注入電極
３ 検出電極
４ 交流電圧生成部
５ 電流検出部
７ 処理部
１２ 被覆電線
１２ａ 中心導体
ｋ 比率
ｋｒｅｆ 基準比率
Ｖ２ 検査交流電圧
Ｖｄ 検出電圧 DESCRIPTION OF SYMBOLS 1 Detection apparatus 2 Injection electrode 3 Detection electrode 4 AC voltage generation part 5 Current detection part 7 Processing part 12 Covered electric wire 12a Center conductor k Ratio kref Reference ratio V2 Inspection AC voltage Vd Detection voltage

Claims (2)

被覆電線の中心導体と容量結合する注入電極と、
前記中心導体と容量結合する検出電極と、
検査交流電圧を生成すると共に当該検査交流電圧を前記注入電極を介して前記中心導体に非接触で注入する交流電圧生成部と、
前記検査交流電圧の注入に起因して前記被覆電線に発生する電流の一部を前記検出電極を介して入力すると共に検出電圧に変換して出力する電流検出部と、
前記検査交流電圧の電圧値に対する前記検出電圧の電圧値の比率を算出すると共に当該算出した比率が予め決められた基準比率以上のときに、前記被覆電線の表面が汚れていると判別する処理部とを備えている被覆電線の表面汚れ検出装置。 An injection electrode capacitively coupled to the central conductor of the covered wire;
A sensing electrode capacitively coupled to the central conductor;
An AC voltage generator for generating an inspection AC voltage and injecting the inspection AC voltage to the central conductor through the injection electrode in a non-contact manner;
A current detection unit that inputs a part of the current generated in the covered electric wire due to the injection of the inspection AC voltage through the detection electrode and converts the detection voltage into a detection voltage, and
A processing unit that calculates the ratio of the voltage value of the detection voltage to the voltage value of the inspection AC voltage and determines that the surface of the covered electric wire is dirty when the calculated ratio is equal to or greater than a predetermined reference ratio. A device for detecting surface contamination of a covered electric wire. 前記被覆電線の表面が汚れていると前記処理部によって判別されたときにその旨を出力する出力部を備えている請求項１記載の被覆電線の表面汚れ検出装置。   The device for detecting surface contamination of a covered electric wire according to claim 1, further comprising an output unit that outputs that when the surface of the covered electric wire is dirty by the processing unit.
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