JP2018132346A - Voltage detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid a decrease in detection accuracy while adopting a configuration in which a detection electrode is brought into contact with an insulating coating to be detected. SOLUTION: A probe main body 31 in which a detection electrode 34 is arranged so as to be in contact with the surface of an insulating coating 51b in a covered electric wire 51 in which an AC voltage to be detected is generated, and a core wire having one end connected to the probe main body 31. The other end of the connection cable 33 in the voltage detection probe 2 having the second connection cable 33 whose one end on the 33a is directly connected to the detection electrode 34 is configured to be connectable, and the other end of the connection cable 33 is connectable. The connection cable 33 is provided with a voltage detection circuit unit VDE that inputs the detection current generated in the core wire 33a according to the potential difference between the second reference potential G2 and the AC voltage to be detected and converts it into the integrated signal V3a and outputs it. In the connected state of the other end of the core wire 33a, a capacitor 21 connected in series between the other end of the core wire 33a and the signal input unit 22a of the voltage detection circuit unit VDE is provided. [Selection diagram] Fig. 2

Description

  The present invention relates to a voltage detection device that detects a voltage to be detected.

  As this type of voltage detection apparatus, the applicant has already proposed a non-contact type voltage measurement apparatus (hereinafter also referred to as “voltage detection apparatus”) disclosed in Patent Documents 1, 2, and 3 below. In these voltage detection devices, even if the detection target (measurement target) is a bare wire without insulation coating, the voltage is detected as a non-contact state (that is, the detection target conductor (core wire when the detection target is an electric wire)). In Patent Document 1, a detection electrode is provided in a sensor substrate storage portion (a casing component formed in a clip shape) formed of a non-conductive resin material so that detection can be performed in a state where the electrode is not in electrical contact. Is employed, and Patent Documents 2 and 3 employ a configuration in which the surface of the detection electrode is covered with an insulating layer (insulating coating).

JP 2014-52329 A (page 5, FIG. 2) JP-A-2006-223866 (page 7-8, FIG. 2) Japanese Unexamined Patent Publication No. 2017-9576 (pages 5-9 and 3-5)

  By the way, this type of voltage detection device employs a configuration in which the detection target voltage is detected by capacitively coupling a detection electrode to the conductor portion of the detection target. It is preferable to satisfactorily capacitively couple the conductor portion and the detection electrode. In view of this, the applicant of the present application provides a favorable detection target conductor and detection electrode in a voltage detection apparatus that detects only a detection target (for example, a covered electric wire) whose conductor is covered with an insulation coating. In order to perform capacitive coupling, a technology has been developed in which the detection electrode is exposed and brought into contact with the insulation coating to be detected. As a result, the detection electrode can be brought closer to the conductor portion to be detected by the thickness of the casing or the thickness of the insulator layer formed on the surface of the detection electrode, compared to the conventional voltage detection device described above. Therefore, it is possible to realize good capacitive coupling.

  However, in the voltage detection device developed by the applicant of the present application, as disclosed in Patent Documents 2 and 3, the detection electrode is connected to the voltage detection unit via the core wire of a shielded cable or a coaxial cable. The configuration directly connected to the input terminal of an operational amplifier (current-voltage conversion computer amplifier) arranged as an input stage is adopted. On the other hand, a conductive path may be formed on the surface of the insulation coating to be detected. The conductive path is formed when a fouling substance such as dust adheres to the surface of the insulating coating, and the fouling substance absorbs moisture in the atmosphere, and reduces the insulation resistance of the surface of the insulating coating. Therefore, the voltage detection device under development by the present applicant adopting the above configuration (configuration in which the detection electrode is directly connected to the input stage of the voltage detection unit through a core wire such as a shielded cable) includes an external magnetic field, an external When a voltage is generated in this conductive path under the influence of an electric field and external noise, a direct current (leakage current) resulting from a potential difference between the voltage of this conductive path and the reference potential of the voltage detection unit described above is generated. There is a problem to be improved that a detection error may occur due to a detection error caused by the DC current being detected as a DC offset in the voltage detection unit by flowing through a core wire such as a shielded cable. .

  The present invention has been made to solve the above-described problems, and mainly provides a voltage detection device that can avoid a decrease in detection accuracy while adopting a configuration in which a detection electrode is brought into contact with an insulation coating to be detected. Objective.

  In order to achieve the above object, a voltage detection apparatus according to claim 1 is provided with a probe main body portion in which a detection electrode is disposed so as to be in contact with a surface of a detection target in which an AC voltage to be detected is generated, and one end of the probe main body portion. And the other end of the connection cable in the voltage detection probe having a connection cable in which the end on the one end side of the core wire included and connected is directly connected to the detection electrode. A voltage detection circuit unit that inputs an AC signal generated in the core wire in accordance with a potential difference between an internal reference potential and the AC voltage to be detected in the connected state of the other end of the cable, converts the signal into a detection signal, and outputs the detection signal. In the voltage detection device, in the connected state of the other end of the connection cable, an end of the core wire on the other end side and a signal input unit of the voltage detection circuit unit And a capacitor connected in series between.

  In the voltage detection device according to claim 1, in the connected state of the voltage detection probe, a capacitor is provided between the other end of the core wire of the connection cable constituting the voltage detection probe and the signal input unit of the voltage detection circuit unit. Connected in series. Therefore, according to this voltage detection device, when a conductive path is formed on the surface of the detection target that is in contact with the detection electrode due to adhesion of a pollutant, a voltage (DC) is applied to the conductive path under the influence of an external magnetic field or the like. Even if a potential difference (DC voltage) occurs between the voltage of the conductive path and the internal reference potential of the voltage detection circuit unit due to this, a DC current (leakage current) due to this potential difference is generated. Occurrence of a situation that flows between the detection electrode and the signal input unit of the voltage detection circuit unit can be blocked by the capacitor. As a result, according to this voltage detection device, a voltage signal (internal reference potential) that accurately represents the AC voltage to be detected can be output without being affected by an external magnetic field or the like (while avoiding a decrease in detection accuracy). Can do.

1 is an external view of a voltage detection device 1 and a voltage detection probe 2. FIG. 1 is a configuration diagram of a voltage detection device 1 and a voltage detection probe 2. FIG. It is a circuit diagram which shows the structure of the current-voltage conversion circuit 22 in the voltage detection circuit unit VDE. It is a circuit diagram which shows the other structure of the current-voltage conversion circuit 22 in the voltage detection circuit unit VDE. It is an external view of the other voltage detection probe 2. FIG.

  Hereinafter, embodiments of a voltage detection device will be described with reference to the accompanying drawings.

  Initially, the structure of the voltage detection apparatus 1 is demonstrated with reference to drawings.

  As shown in FIGS. 1 and 3, the voltage detection device 1 includes a case 11, an input connector 12, and a connection cable 13 (hereinafter referred to as a first connection cable 13 to distinguish it from a connection cable 33 of the voltage detection probe 2 described later). And the voltage detection probe 2 is detachably connectable to the input connector 12, and the first connection cable 13 is detachably connectable to an input connector (not shown) of a waveform observation apparatus such as an oscilloscope. It is configured. The voltage detection device 1 functions as a metal non-contact type voltage detection device together with the voltage detection probe 2.

  The case 11 is formed in a box (for example, a rectangular parallelepiped) that can store an electronic circuit inside using an insulating resin material. In addition, inside the case 11, as shown in FIG. 2, a capacitor 21, a current-voltage conversion circuit 22, an integration circuit 23, an insulation type signal transmission circuit 24 (hereinafter also simply referred to as an insulation circuit 24), an amplification circuit 25, A phase compensation circuit 26, a voltage generation circuit 27, and a power supply circuit (not shown) are accommodated as the electronic circuit.

  In this case, the power supply circuit has a first operating voltage (amplifier circuit 25, phase compensation circuit) based on the first reference potential (the voltage of the first ground G1; hereinafter also referred to as the first reference potential G1) shown in FIG. 26 and a voltage generation circuit 27 for generating a main power supply circuit for generating a voltage for the voltage generator VGE, and a second reference potential (a second ground G2 as an internal reference potential) based on the voltage for operation. In the following, the second operation voltage (hereinafter also referred to as the second reference potential G2) is used for the operation for the voltage detection circuit unit VDE including the current-voltage conversion circuit 22, the integration circuit 23, and the insulation circuit 24. Equivalent to the configuration having an isolated DC / DC converter that generates voltages Vf + and Vf− (see FIG. 4) and having a main power supply circuit and a DC / DC converter disclosed in Patent Documents 2 and 3 above. It is configured. When the case 11 is configured to be able to store a battery, the main power supply circuit is operated by power supply from the battery, and a USB power supply connector or an AC adapter connector is attached to the case 11. In the case where it is provided, it is operated by power supplied from the outside via a USB cable or a power cable connected to an AC adapter.

  The input connector 12 is constituted by a receptacle of a coaxial connector such as a BNC connector, for example, and is fixed to the wall portion so as to penetrate one wall portion of the case 11 as shown in FIGS. As will be described later, the center conductor 12a of the input connector 12 is connected to one end of the capacitor 21, and the cylindrical outer conductor 12b of the input connector 12 covers the voltage detection circuit unit VDE and applies the second reference potential G2. Thus, the guard electrode 28 guards the voltage detection circuit unit VDE from external noise or the like (to reduce the influence of the external noise or the like) (hereinafter also referred to as a first guard electrode 28 in order to distinguish from the guard electrode 35 described later). Is electrically connected.

  The capacitor 21 has one end connected to the central conductor 12a of the input connector 12, and the other end connected to the signal input unit 22a of the voltage detection circuit unit VDE (specifically, an input part (input) for inputting a signal in the current-voltage conversion circuit 22) Terminal)). Further, the capacitor 21 is composed of a capacitor with a small leakage current (for example, a ceramic capacitor, a film capacitor, a mica capacitor, etc.).

  As shown in FIG. 3 as an example, the current-voltage conversion circuit 22 constituting the voltage detection circuit unit VDE has a non-inverting input terminal connected to the first guard electrode 28 defined by the second reference potential G2 via a resistor 22b. In addition, the inverting input terminal is connected to the signal input unit 22a (that is, to the other end of the capacitor 21 connected to the signal input unit 22a), and the feedback resistor 22c is interposed between the inverting input terminal and the output terminal. The connected operational amplifier 22d is provided and is configured in the same manner as the current-voltage conversion circuit disclosed in Patent Documents 2 and 3 above. In the current-voltage conversion circuit 22, when the operational amplifier operates with the positive voltage Vf + and the negative voltage Vf−, the conductor portion of the detection target 51 (when the detection target 51 is a covered electric wire as shown in FIGS. The detection target AC voltage V1 and the second reference potential G2 (which is also a voltage of a voltage signal V4 described later output from the voltage generation unit VGE) generated in the core wire 51a whose outer periphery is covered with the insulating coating 51b in the covered electric wire 51) Between the core wire 51a of the covered electric wire 51 and the current-voltage conversion circuit 22 through the voltage detection probe 2 at a current value corresponding to the first potential difference. The detection current (current signal as an alternating current signal) I flowing between is converted into a detection voltage signal V2 and output.

  Note that the current-voltage conversion circuit 22 is not limited to the configuration shown in FIG. 3. For example, as shown in FIG. 4, a resistor 22 e is connected between the signal input unit 22 a and the first guard electrode 28. The detection current I is converted into a voltage, and the operational amplifier 22d functions as an amplifier (in FIG. 4, the operational amplifier 22d functions as a voltage follower as an example, but the operational amplifier 22d functions as an inverting amplifier or a non-inverting amplifier. The voltage generated at both ends of the resistor 22e may be converted into a detection voltage signal V2 and output. In addition, the same code | symbol is attached | subjected about the structure same as the structure shown in FIG. 3, and the overlapping description is abbreviate | omitted.

  For example, the integration circuit 23 is configured in the same manner as the integration circuit disclosed in Patent Documents 2 and 3 described above, and integrates the detection voltage signal V2 to thereby detect the detection target AC voltage V1 and the second reference potential G2. An integrated signal V3 whose voltage value changes in proportion to the first potential difference between is generated and output. The insulating circuit 24 includes, for example, a drive circuit disclosed in Patent Documents 2 and 3, an insulating circuit (follower coupler) driven by the driving circuit, and a circuit configured by a resistor connected to the insulating circuit. The integration signal V3 having the same configuration and the second reference potential G2 as a reference is converted into an integration signal V3a (a voltage detection signal whose voltage value changes in proportion to the first potential difference (voltage detection). Converted into a detection signal)) output from the circuit unit VDE.

  The voltage generation unit VGE forms a feedback loop together with the voltage detection circuit unit VDE to amplify the integration signal V3a so as to reduce the first potential difference between the detection target AC voltage V1 and the second reference potential G2 (feedback). By performing the control operation, the voltage signal V4 is generated and applied (output) to the first guard electrode 28 as the second reference potential G2 in the voltage detection circuit unit VDE.

  As an example, the amplification circuit 25, the phase compensation circuit 26, and the voltage generation circuit 27 constituting the voltage generation unit VGE are the amplification circuit, the phase compensation circuit, and the booster in the voltage generation unit disclosed in Patent Documents 2 and 3 above. Each circuit is configured equivalently. Thus, the amplifier circuit 25 generates the voltage signal V4a by inputting and amplifying the integration signal V3a. Further, the phase compensation circuit 26 receives the voltage signal V4a, adjusts its phase, and outputs it as the voltage signal V4b in order to stabilize the above feedback control operation (prevent oscillation). The voltage generation circuit 27 generates the voltage signal V4 by boosting the voltage signal V4b at a predetermined magnification, and applies the voltage signal V4 to the second reference potential G2.

  By this feedback control operation, the first potential difference between the detection target AC voltage V1 and the second reference potential G2 is controlled to be substantially zero volts, so that the second reference potential G2, that is, the voltage signal V4, is detected AC. It is controlled to the same voltage as the voltage V1.

  The voltage signal V4 is also output to the core wire 13a included in the first connection cable 13 (for example, a shielded cable such as a coaxial cable) integrally connected to the case 11. A connector 14 (for example, a plug of a coaxial connector such as a BNC connector) that can be connected to an input connector (receptacle) of the waveform observation apparatus is attached to the tip of the first connection cable 13.

  As shown in FIG. 1 as an example, the voltage detection probe 2 includes a probe main body 31 and a connection cable 33 (first connection cable 13) having one end coupled to the probe main body 31 and a connector 32 attached to the other end. The second connection cable 33 is also provided for distinction.

  As an example, the probe main body 31 is substantially equivalent to any one of the voltage detection probes disclosed in Patent Documents 2 and 3 described above (the surface of a detection electrode 34 described later is covered with an insulator layer (insulation coating)). A concave portion (concave groove) 31a for being hooked on a covered electric wire (hereinafter also referred to as a covered electric wire 51) as the detection target 51 is formed at the tip. The probe main body 31 is provided with a detection electrode 34 whose surface is not covered with an insulator layer (insulation coating). With this configuration, in the probe main body 31, the detection electrode 34 is covered with the covered electric wire 51 in a state where it is hooked on the covered electric wire 51 (a state where the covered electric wire 51 is located inside the recess 31 a and detects the detection target AC voltage V <b> 1). It is possible to directly contact the surface (surface of the insulation coating). Further, as shown in FIG. 2, the detection electrode 34 is capacitively coupled to the core wire 51 a of the covered electric wire 51 while being in direct contact with the surface of the covered electric wire 51. In the probe main body 31, a guard electrode 35 (also referred to as a second guard electrode 35 for distinguishing from the first guard electrode 28) for reducing the influence of external noise on the detection electrode 34 is provided on the detection electrode 34. On the other hand, it is disposed in an electrically insulated state.

  Note that the probe main body 31 is not limited to the configuration in which the concave portion 31a hooked on the covered electric wire 51 as shown in FIG. 1 is formed. For example, the probe main body 31 is disclosed in Patent Document 1 as shown in FIG. A casing (a probe in this example) having a configuration substantially equivalent to a voltage measurement sensor (corresponding to the voltage detection probe in this example) (including a sensor substrate housing portion 41 and a measurement target conductor pressing portion 42). (Corresponding to the main body portion), and a configuration in which the covered electric wire 51 is sandwiched between the sensor substrate housing portion 41 and the measurement target conductor pressing portion 42) may be employed. However, the configuration related to the detection electrode 34 is different from the configuration of the voltage measurement sensor of Patent Document 1 in that the detection electrode 34 is exposed from the outer wall portion of the sensor substrate housing portion 41. Thereby, the surface of the covered electric wire 51 sandwiched between the sensor substrate housing portion 41 and the measurement target conductor pressing portion 42 can come into contact with the detection electrode 34.

  The second connection cable 33 is composed of a shielded cable such as a coaxial cable, and as shown in FIG. 2, the end of the second connection cable 33 in the included core wire 33 a (internal conductor) is the detection electrode 34. In addition, the end of one end side of the second connection cable 33 in the shield layer 33 b (external conductor) covering the core wire 33 a is directly connected to the second guard electrode 35.

  The connector 32 is configured to be connectable to the input connector 12 disposed in the case 11. In this example, since the input connector 12 is constituted by the receptacle of the coaxial connector as described above, the connector 32 is constituted by a plug of the same type of coaxial connector that can be connected to the receptacle. The central conductor 32a of the connector 32 is directly connected to the end of the second connection cable 33 on the core wire 33a, and the external conductor 32b of the connector 32 is connected to the second connection cable 33 on the shield layer 33b. It is directly connected to the end on the other end side.

  Next, a detection procedure for the operation of the voltage detection device 1 and the voltage detection probe 2 when detecting the detection target AC voltage V1 generated in the core wire 51a of the covered electric wire 51 using the voltage detection device 1 and the voltage detection probe 2 is performed. It explains together. Note that the power supply circuit in the case 11 operates by supplying power from the above-described battery or the like, and generates operating voltages for the voltage generating unit VGE and operating voltages Vf + and Vf− for the voltage detecting circuit unit VDE. Thus, it is assumed that the voltage generation unit VGE and the voltage detection circuit unit VDE are in an operating state.

  First, the connector 32 of the voltage detection probe 2 is connected to the input connector 12 of the voltage detection device 1. As a result, the center conductor 32a of the connector 32 is connected to the center conductor 12a of the input connector 12, and the outer conductor 32b of the connector 32 is connected to the outer conductor 12b of the input connector 12, as shown in FIG. The detection electrode 34 on the voltage detection probe 2 side is directly connected to one end of the capacitor 21 on the voltage detection device 1 side via the core wire 33a of the second connection cable 33, and the second guard electrode on the voltage detection probe 2 side. 35 is directly connected to the first guard electrode 28 on the voltage detection device 1 side via the shield layer 33 b of the second connection cable 33. Further, the connector 14 attached to the tip of the first connection cable 13 of the voltage detection device 1 is connected to the input connector of the waveform observation device. Thereby, the voltage signal V4 output from the first connection cable 13 can be observed (measured) by the waveform observation device.

  Next, the probe main body 31 of the voltage detection probe 2 is held by hand and the covered electric wire 51 is inserted into the recess 31 a, so that the probe main body 31 is hooked on the covered electric wire 51. Thereby, as shown in FIGS. 2 and 3, the detection electrode 34 provided on the probe main body 31 comes into contact with the insulating coating 51b of the covered electric wire 51 located inside the recess 31a. Further, as a result, the detection electrode 34 is capacitively coupled with the core wire 51 a of the covered electric wire 51 in a good state, so that the voltage detection device 1 and the voltage detection probe 2 are detected ACs generated on the core wire 51 a of the covered electric wire 51. The detection operation of the voltage V1 is started.

  Specifically, as shown in FIG. 3, since the detection electrode 34 is capacitively coupled to the core wire 51a of the covered electric wire 51 via the coupling capacitor C, the core wire 51a and the signal input unit 22a of the voltage detection circuit unit VDE are connected. In the meantime, this first potential difference is caused by the first potential difference between the detection target AC voltage V1 generated in the core wire 51a and the second reference potential G2 (voltage of the voltage signal V4 output from the voltage generation unit VGE). A detection current (alternating current) I having a current value corresponding to the current flows through the detection electrode 34, the core wire 33 a of the second connection cable 33, and the capacitor 21.

  In the voltage detection circuit unit VDE, the current-voltage conversion circuit 22 converts this detection current I into a detection voltage signal V2 and outputs it. In this case, a conductive path (conductive path described in the above-described problem to be solved by the invention) is formed on the surface of the insulating coating 51b of the covered electric wire 51, and an external magnetic field, an external electric field, and an external noise are formed. As a result, a potential difference (DC voltage) is generated between the voltage of the conductive path and the second reference potential G2 (voltage of the voltage signal V4) of the voltage detection circuit unit VDE. Even if this occurs, the capacitor 21 prevents the DC current (leakage current) caused by this potential difference from flowing between the detection electrode 34 and the signal input unit 22a of the voltage detection circuit unit VDE. Therefore, even if the current-voltage conversion circuit 22 is affected by the external magnetic field or the like and a voltage is generated in the conductive path, the current-to-voltage conversion circuit 22 is not affected by the voltage, and the detection target AC voltage V1 and the second reference potential G2 ( Only the detection current I generated due to the first potential difference with the voltage of the voltage signal V4) is converted into the detection voltage signal V2 and output.

  As a result, the voltage detection circuit unit VDE including the current-voltage conversion circuit 22, the integration circuit 23, and the insulation circuit 24 performs an integration signal V3a (detection target AC voltage) with the first reference potential G1 as a reference. An integrated signal whose voltage value changes in proportion to the first potential difference between V1 and the second reference potential G2.

  In addition, the voltage generation unit VGE that forms a feedback loop together with the voltage detection circuit unit VDE generates the voltage signal V4 by amplifying the integration signal V3a so as to reduce the first potential difference, and the voltage signal V4 is A feedback control operation of applying to the guard electrode 28 of the detection circuit unit VDE is executed. By this feedback control operation, the first potential difference between the detection target AC voltage V1 and the second reference potential G2 is controlled to be substantially zero. Therefore, the second reference potential G2, that is, the voltage signal V4 is equal to the detection target AC voltage V1. It is controlled (to match) the same voltage. Further, since this voltage signal V4 is output to the waveform observation device via the first connection cable 13, the voltage signal V4, that is, the detection target AC voltage V1 can be observed in this waveform observation device.

  Thus, in the voltage detection device 1 in which the voltage detection probe 2 in which the detection electrode 34 is in contact with the surface of the insulating coating 51b in the covered electric wire 51 is connected, the voltage detection probe 2 is configured in the connected state of the voltage detection probe 2. The other end of the core wire 33a of the second connection cable 33 (the end on the side where the connector 32 is attached) and the voltage detection circuit unit VDE (in this example, the current voltage constituting the voltage detection circuit unit VDE) A capacitor 21 is connected in series (interposed) to the signal input unit 22a) of the conversion circuit 22.

  Therefore, according to the voltage detection device 1, when a conductive path is formed by adhesion of a pollutant on the surface of the insulating coating 51b with which the detection electrode 34 contacts, the conductive path is affected by an external magnetic field or the like. Even if a voltage (DC voltage) is generated, and due to this, a potential difference (DC voltage) occurs between the voltage of the conductive path and the second reference potential G2 (voltage of the voltage signal V4) of the voltage detection circuit unit VDE. The occurrence of a situation in which a direct current (leakage current) caused by this potential difference flows between the detection electrode 34 and the signal input unit 22a of the voltage detection circuit unit VDE can be prevented by the capacitor 21. Thus, according to the voltage detection device 1, the voltage signal V4 that accurately represents the voltage of the detection target AC voltage V1 is output without being affected by an external magnetic field or the like (while avoiding a decrease in detection accuracy). Can do.

  As indicated by a broken line in FIG. 3, in the connected state of the voltage detection probe 2, the current-voltage conversion circuit 22 of the voltage detection circuit unit VDE to which the core wire 33 a of the second connection cable 33 constituting the voltage detection probe 2 is connected. When the surge absorber 29 (diode, varistor, etc.) is disposed between the signal input portion 22a and the second reference potential G2, the capacitor 21 is connected to the surge absorber 29 as shown in FIG. It is preferable to employ a configuration that is disposed at a position closer to the signal input portion 22a than the point A. By adopting this configuration, even if a leakage current (DC current) occurs in the surge absorber 29, the current-voltage conversion circuit 22 detects the current I while blocking the influence of the leakage current with the capacitor 21. Can be converted into a detection voltage signal V2 and output, so that a voltage signal V4 that accurately represents the voltage of the detection target AC voltage V1 can be output.

  In addition, the voltage detection device 1 described above employs a configuration that includes the input connector 12 and can removably connect the voltage detection probe 2 having the connector 32 attached to the other end of the second connection cable 33. Although not shown, the input connector 12 and the connector 32 are omitted, and the end of the second connection cable 33 on the core wire 33a of the second connection cable 33 is directly connected to one end of the capacitor 21. Configuration in which the end of the second connection cable 33 in the shield layer 33b of the second connection cable 33 is directly connected (integratedly connected) to the first guard electrode 28 housed in the case 11 (voltage detection) It is also possible to adopt a configuration in which the probe 2 cannot be attached or detached. Although not shown, a configuration in which the voltage detection device 1 is built in the waveform observation device may be employed.

DESCRIPTION OF SYMBOLS 1 Voltage detection apparatus 2 Voltage detection probe 21 Capacitor 22 Current-voltage conversion circuit 22a Signal input part 31 Probe main body 33 2nd connection cable 34 Detection electrode 51 Covered electric wire (detection object)
51a Core wire G2 Second reference potential I Detection current V1 Detection target AC voltage

Claims (1)

A probe main body part in which a detection electrode is disposed so as to be able to contact the surface of the detection target in which an AC voltage to be detected is generated, and an end part on the one end side of the core wire having one end connected to the probe main body part and contained therein The other end of the connection cable in the voltage detection probe having a connection cable directly connected to the detection electrode is configured to be connectable, and the internal reference potential and the detection target in the connection state of the other end of the connection cable A voltage detection device including a voltage detection circuit unit that inputs an AC signal generated in the core wire in accordance with a potential difference with an AC voltage, converts the signal into a detection signal, and outputs the detection signal.
The voltage detection apparatus provided with the capacitor | condenser connected in series between the edge part of the said other end side in the said core wire, and the signal input part of the said voltage detection circuit part in the connection state of the said other end of the said connection cable.

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