JP6495103B2 - Voltage detection probe and measuring device - Google Patents

Description

  The present invention relates to a voltage detection probe configured to be able to detect the voltage of a conductor to be measured, and a measurement apparatus including the voltage detection probe.

  As this type of voltage detection probe, the applicant of the present application discloses various types of voltage detection probes (hereinafter also simply referred to as “detection probes”) in Patent Documents 1 to 3 below. For example, Patent Document 1 discloses a detection probe that includes a clamp portion in which a magnetic core that surrounds an electric wire to be measured and forms an annular closed magnetic path in a closed state is incorporated. In Patent Document 2, a sensor substrate housing portion that houses a voltage measurement sensor substrate, and a sensor substrate housing portion that is pivotally supported by a sensor substrate housing portion via a rotation shaft, and a measurement target conductor is connected to the sensor substrate housing portion. The detection probe of the structure provided with the measurement object electric wire pressing part clamped between is disclosed. Moreover, in patent document 3, it has a voltage detection part by which the detection electrode for a voltage detection and a magnet are arrange | positioned inside, and is measuring object, positioning the front-end | tip part of the measurement probe provided with the voltage detection part with the magnetic force of a magnet A detection probe configured to be pressed against an electric wire is disclosed. Each of these detection probes is a detection probe (so-called non-contact type) that can detect the voltage of the conductive portion by simply capacitively coupling the detection electrodes to each other without directly contacting the conductive portion of the electric wire to be measured. Voltage detection probe).

Japanese Unexamined Patent Publication No. 2012-137496 (5th page, FIG. 1) JP 2014-52329 A (page 5-8, FIG. 1-3) JP 2014-163670 A (page 5-8, Fig. 1-3)

  However, each of the detection probes described above has the following problems to be improved. In other words, these detection probes have a configuration in which a magnetic core, a mechanism for clamping and clamping, or a magnet is arranged in the vicinity of the voltage detection electrode. In particular, the shape of the part including the electrode for voltage detection is large.

  Therefore, these detection probes are in the vicinity (periphery) of the portion where the detection probe is mounted, such as an overhead wire, a lead-in wire from the overhead wire to the indoor, an electric wire used for indoor wiring (usually a covered electric wire). It is possible to use it for a conductor to be measured in which a certain amount of space exists. However, in these detection probes, for example, a wiring material having a small diameter (for example, a diameter of 2 mm or less) for supplying an operating voltage to a circuit board disposed in an electronic device, which is usually other same This lead of one of the wiring materials routed in a state of being bundled together with such a small-diameter wiring material, or an electronic component which is a discrete component mounted on a circuit board and has a certain length of lead wire exposed Other conductors (such as other wiring materials, other lead wires, and wiring patterns on which test points are mounted, such as one of the wires and one of the columnar test points mounted on the circuit board. It is difficult to attach to one conductor that is in close proximity to other wiring patterns), and there is a problem that this point should be improved.

  The present invention has been made to improve such a problem, and a voltage detection probe that can be attached to a conductor to be measured that exists in a state of being in close proximity to other conductors, and a measurement including this voltage detection probe The main purpose is to provide a device.

  In order to achieve the above object, the voltage detection probe according to claim 1 includes a rod-shaped detection electrode having a distal end portion formed on a hook portion that is hooked on a conductor to be measured and a proximal end portion connected to a connection cable, An insulator layer is formed on the surface of the detection electrode, and the surface of the insulator layer excluding a non-formation region defined in at least a part of a surface facing the measurement target conductor in the hooking portion, A conductive layer electrically insulated from the detection electrode is formed, and the detection electrode is configured to be capable of capacitive coupling via the measurement target conductor hooked on the hook portion and the non-formation region. Yes.

  The voltage detection probe according to claim 2 is the voltage detection probe according to claim 1, wherein the hooking portion is provided with a concave groove in the tip portion along a direction intersecting with an axis of the detection electrode. Is formed by.

  The voltage detection probe according to claim 3 is the voltage detection probe according to claim 2, wherein the voltage detection probe is on the tip end side of the detection electrode of the pair of inner wall surfaces parallel to the intersecting direction in the concave grooves and facing each other. The front end side inner wall surface located is inclined toward the base end portion with reference to a reference plane orthogonal to the axis.

  The voltage detection probe according to claim 4 is the voltage detection probe according to claim 3, wherein a base end side inner wall surface located on the base end portion side of the pair of inner wall surfaces is based on the reference plane. It is inclined toward the base end side with respect to the inner wall surface on the front end side.

  A voltage detection probe according to a fifth aspect is the voltage detection probe according to the third or fourth aspect, wherein the non-formation region is defined on the inner wall surface on the front end side.

  A voltage detection probe according to a sixth aspect is the voltage detection probe according to any one of the first to fifth aspects, wherein the conductor layer is covered with a covering layer having electrical insulation.

  The voltage detection probe according to claim 7 is the voltage detection probe according to claim 6, wherein the detection electrode is exposed from the insulator layer and the conductor layer at the base end portion, and the conductor layer is The base end portion is exposed from the coating layer.

  The voltage detection probe according to claim 8 is the voltage detection probe according to any one of claims 1 to 7, wherein the connection cable is connected, the base end side is inserted, and the hook portion is exposed. The grip portion is fixed to the grip portion in a state where the detection electrode is fixed, and the end portion where the hook portion is exposed in the grip portion is inserted from the rear end opening portion. And a sheath part slidable between a first position where the hooking part protrudes from the tip opening along the axis of the detection electrode and a second position where the hooking part immerses into the tip opening. And a biasing member that is disposed between the grip portion and the sheath portion and constantly biases the sheath portion in the second position direction.

The voltage detection probe according to claim 9 is the voltage detection probe according to claim 8, wherein the connection cable is formed of a coaxial cable, and the base end portion is directly connected to a core wire of the coaxial cable in the grip portion. And is covered with a shield member defined to have the same potential as that of the outer conductor of the coaxial cable.

The measuring device according to claim 10 is configured such that the voltage is detected via the connection cable including the voltage detection probe according to any one of claims 1 to 9 and a coaxial cable in which a core wire is directly connected to the base end portion. a main unit connected to the detection probes, disposed within the body unit, changes according to the voltage and detects the core wire and the measurement object conductor voltage through the detection electrode of the coaxial cable A voltage detection unit that outputs a voltage signal; and a voltage detection unit that is disposed in the main body unit, generates a voltage that follows the voltage of the conductor to be measured based on the voltage signal, and applies the voltage to the outer conductor of the coaxial cable A voltage generator; and a processing unit that is disposed in the main body unit and measures the voltage of the conductor to be measured based on the voltage generated by the voltage generator. Wherein the voltage detection unit operates at a floating voltage with respect to the potential of the voltage generated by the voltage generator.
The measurement device according to claim 11 is the measurement device according to claim 10, wherein the voltage detection unit includes a current-voltage conversion circuit configured to include an operational amplifier, and the operational amplifier has an inverting input terminal as the inverting input terminal. A non-inverting input terminal is defined by the potential of the voltage generated by the voltage generator, and the outer conductor of the coaxial cable is generated by the voltage generator. And is connected to the conductor layer on the voltage detection probe side.

  In the voltage detection probe according to claim 1 and the measurement apparatus according to claim 10, the detection electrode is formed in a rod shape in which a distal end portion is formed in a hook portion and a connection cable is connected to a proximal end portion. On the surface, a conductor layer is formed in a state where a non-formation region is defined on the surface of the hook portion facing the measurement target conductor and is electrically insulated from the detection electrode.

  Therefore, according to the voltage detection probe and the measurement apparatus, the detection electrode can be formed of a thin rod-shaped body as long as the hook portion that can be hooked on one conductor as the measurement target conductor can be formed at the tip portion. In addition, while having a simple configuration in which the conductor layer having the above-described configuration is formed on the surface of the detection electrode, it is possible to shield the detection electrode while enabling capacitive coupling between the conductor to be measured and the detection electrode. Therefore, even for the conductor to be measured that is in close proximity to other conductors, the influence of the disturbance on the detection electrode is reduced by the conductor layer, and the detection electrode is attached by hooking the hook. As a result, it is possible to reliably and easily measure the voltage of the conductor to be measured.

  According to the voltage detection probe according to claim 2 and the measurement apparatus according to claim 10, the hook portion is formed by providing a concave groove at the tip of the rod-like detection electrode by a simple method such as cutting. For example, unlike the hook portion formed by bending the tip end portion of the rod-shaped detection electrode, the size of the hook portion can be approximately the same as the thickness of the detection electrode. Therefore, according to the detection probe and the measurement apparatus, the voltage can be measured by attaching to the measurement target conductor having a shorter distance from other adjacent conductors.

  According to the voltage detection probe according to claim 3 and the measurement device according to claim 10, when the detection probe is hooked on the measurement target conductor, the distal end side inner wall surface is inclined toward the base end side. It is possible to make it difficult to remove the conductor to be measured from the hook portion.

  According to the voltage detection probe according to claim 4 and the measurement device according to claim 10, the distal end inner wall surface is configured to have a configuration in which the proximal end inner wall surface is inclined to the proximal end side with respect to the distal end side inner wall surface. Realizing further ease of accommodation of the measurement target conductor in the concave groove while maintaining the effect when tilted to the base end side (effect that the measurement target conductor cannot be easily detached from the hook). be able to.

  According to the voltage detection probe according to claim 5 and the measurement device according to claim 10, when the detection probe is hooked on the measurement target conductor, the entire inner wall surface on the front end side that mainly comes into contact with the measurement target conductor is electrically conductive. By adopting a configuration in which the layer is not formed or a configuration in which only a part of the inner wall surface on the front end side is a non-formed region, a conductor layer is formed on other portions of the inner surface of the groove. Can do. Therefore, while the capacitive coupling between the detection electrode and the measurement target conductor through this non-formation region is possible, the shielding effect of the conductor layer on the detection electrode is further enhanced, and the measurement accuracy of the voltage of the measurement target conductor is further improved. be able to.

  According to the voltage detection probe according to claim 6 and the measurement device according to claim 10, even when another conductor is present adjacent to the conductor to be measured, the presence of the covering layer causes the object to be measured. It is possible to reliably prevent the occurrence of a situation where the conductor and the other conductor are short-circuited via the conductor layer formed on the surface of the detection electrode.

  According to the voltage detection probe according to claim 7 and the measurement device according to claim 10, the detection electrode is exposed from the insulator layer and the conductor layer at the base end portion, and the conductor layer is at the base end portion of the detection electrode. Since the structure is exposed from the coating layer, the connection cable on the base end side of the detection electrode inserted into the grip portion, and the detection electrode and the conductor layer can be easily connected.

  According to the voltage detection probe according to claim 8 and the measurement device according to claim 10, the measurement target conductor accommodated in the concave groove is moved to the tip side inner wall surface of the concave groove by the biasing force of the biasing member. Since it can be clamped between the lip of the distal end opening in the sheath part, the state in which the hook is hooked on the conductor to be measured is maintained even when the detection probe is released. The workability of the conductor voltage measurement work can be improved.

  According to the voltage detection probe according to claim 9 and the measurement device according to claim 10, the base end side of the detection electrode is a shield member that is regulated to the same potential as the potential of the outer conductor of the coaxial cable in the grip portion. Coaxial cable that is exposed for connection to the surface of all other detection electrodes except for the non-formation region of the conductor layer defined on the inner surface of the groove, and the connection to the detection electrode. As a result of being able to shield the core wire without any gap, it is possible to further improve the measurement accuracy of the voltage of the conductor to be measured.

1 is a configuration diagram of a detection probe 1. FIG. It is sectional drawing along the axis line L for demonstrating the structure of the detection electrode 11 and the plunger 2 of FIG. It is sectional drawing along the axis line L for demonstrating the shield structure in the base end side of the plunger 2 of FIG. It is sectional drawing along the axis line L for demonstrating the other shield structure in the base end side of the plunger 2 of FIG. It is explanatory drawing (diagram in the state in which the sheath part 4 is located in a 1st position) for demonstrating hooking operation with respect to the measuring object conductor 8 by the detection probe 1. FIG. It is explanatory drawing for demonstrating operation which accommodates the measuring object conductor 8 in the ditch | groove 22 of the plunger 2 of the state of FIG. FIG. 6 is an explanatory diagram for explaining a state in which a measurement target conductor 8 in a concave groove 22 is sandwiched between a sheath portion 4 and a detection electrode 11. It is a block diagram of measuring apparatus MD. 4 is an enlarged view of a main part for explaining the configuration of another concave groove 22 of the detection electrode 11. FIG. It is a perspective view of the detection electrode 11 of FIG. FIG. 11 is an explanatory diagram for explaining a state in which a measurement target conductor 8 in a concave groove 22 is sandwiched between a sheath portion 4 and a detection electrode 11 shown in FIGS.

  Hereinafter, embodiments of a voltage detection probe and a measurement apparatus will be described with reference to the accompanying drawings.

  First, the configuration of a voltage detection probe (hereinafter also simply referred to as “detection probe”) 1 as the voltage detection probe shown in FIG. 1 will be described with reference to the drawings.

  As shown in FIG. 1, the detection probe 1 includes a plunger 2, a grip part 3, a sheath part 4, and an urging member 5, and constitutes a measuring device MD together with a body unit 6 (see FIG. 8) described later. To do. The detection probe 1 is connected to the main unit 6 via a coaxial cable (hereinafter also referred to as the coaxial cable 7) as an example of the connection cable 7, and is connected to the measurement target conductor 8 (see FIGS. 6 and 7). 2 is used by hooking the tip (left end in the figure). In this case, the connection cable is not limited to the coaxial cable 7, and a twisted pair wire or the like can be used.

  As shown in FIG. 2, the plunger 2 includes a detection electrode 11, an insulator layer 12, a conductor layer 13, and a coating layer 14.

  Specifically, the detection electrode 11 is a member constituting the main body of the plunger 2, and as shown in FIGS. 1 and 2, the outer shape of the detection electrode 11 is a rod-like rigidity using a conductive material (conductive metal material). In addition to being formed into a body (in other words, a rigid rod-like body), the tip portion is formed at the hooking portion 21 that hooks the conductor 8 to be measured. In this example, as an example, the hooking portion 21 is along a direction intersecting with the axis L of the detection electrode 11 (in this example, a direction orthogonal to the example, that is, a direction from the near side to the far side of the drawing). Thus, the groove 22 is provided at the tip of the detection electrode 11 so that the detection electrode 11 is formed in a hook shape as a whole. In addition, as shown in FIGS. 1 and 2 as an example, the concave groove 22 of the present example is configured to be formed in a U shape in a side view in which the bottom surface is curved in an arc shape, but is not limited thereto. Although not shown in the drawings, a configuration in which the bottom surface side is formed in a U shape in a side view in which the bottom surface side is formed in a planar shape may be used. The concave groove 22 is formed by a technique such as cutting.

  In addition, as described above, the tip end of the detection electrode 11 is formed in the hook-shaped hook portion 21, as described above, by simply forming the groove 22 without bending the tip end of the detection electrode 11. Although not shown in the figure, the configuration is such that, for example, the tip of the detection electrode 11 formed of a thin rod-like body is bent into an L shape, a U shape, or a V shape. It can also be adopted. In the hooking portion having this configuration, the facing surfaces of the bent portion at the distal end portion of the detection electrode and the non-folded portion adjacent to the bent portion are the facing surfaces to the measurement target conductor 8. For this reason, the below-mentioned non-formation area | region in the conductor layer 13 is prescribed | regulated to at least one part of these opposing surfaces.

  The measurement target conductor 8 in which the detection probe 1 of the present example is used is a conductor that has been difficult to mount with the various detection probes described in the background art, for example, usually with other similar small-diameter wiring materials. For example, one small wiring material routed in a bundled state, one lead wire of an electronic component mounted on a circuit board, one test point mounted on a circuit board, etc. It is a single small-diameter conductor that exists in close proximity to a conductor (another wiring material, another lead wire, another wiring pattern close to the wiring pattern on which the test point is mounted, etc.).

  For this reason, the detection electrode 11 of the detection probe 1 has a thinner rod-like body as long as the concave groove 22 having such a width and depth that such a small-diameter conductor can be accommodated as the measurement target conductor 8 can be formed at the tip. Can be used. Further, in order to be able to be hooked on the measurement target conductor 8 even when the distance between the measurement target conductor 8 and another conductor adjacent to the measurement target conductor 8 is short, the detection electrode 11 is connected to the detection electrode 11. It is preferable that the rod-shaped body to be used is as thin as possible. In addition, the detection electrode 11 has a thin rod shape only at the distal end portion that forms the concave portion 22 and serves as the hooking portion 21, and the proximal end side inserted into the grip portion 3 as described later is closer to the distal end portion side. Although it is possible to adopt a configuration having a thick bar shape, as shown in FIGS. 1 and 2, it is preferable to use a bar shape having a substantially uniform thickness with less processing effort. For example, in order to accommodate a wiring material having a small diameter (diameter of about 2 mm) as described above, the concave groove 22 is, for example, a depth slightly deeper than 2 mm and a width slightly wider than 2 mm (opening width). Need to be formed. For this reason, for example, when the detection electrode 11 is constituted by a rod-shaped member having a circular cross section (that is, a columnar member), it is preferable to use a columnar member having a diameter of about 3 mm to 4 mm, for example. When only the conductor having a smaller diameter is used as the measurement target conductor 8, the depth and the opening width of the concave groove 22 can be reduced in accordance with the thickness of the measurement target conductor 8. Of course, the detection electrode 11 can be formed of a rod-like body having a thickness of about 2 mm.

  As an example in this example, the concave groove 22 is, as shown in FIG. 2, the detection electrode 11 of the pair of inner wall surfaces 22 a and 22 b that are parallel to the intersecting direction in the concave groove 22 and face each other. An inner wall surface 22a as a distal end side inner wall surface located on the distal end side (left end side in the figure) is formed substantially parallel to a reference plane PL (plane orthogonal to the drawing surface) orthogonal to the axis L, and a pair of inner walls Of the wall surfaces 22a and 22b, an inner wall surface 22b as a proximal end inner wall surface located on the proximal end side (the right end side in the figure) of the detection electrode 11 is also formed substantially parallel to the reference plane PL.

  As an example, as shown in FIGS. 1 and 2, the insulator layer 12 includes a base end side portion on the surface of the detection electrode 11 (in this example, the base end side end surface and a certain distance from the end surface ( For example, it is formed in all other parts except the outer peripheral surface included within several mm). As an example, in this example, the insulator layer 12 is formed on the surface of the detection electrode 11 with a thickness of, for example, about several millimeters of comma (about 0.1 mm as an example) using a synthetic resin material having electrical insulation. ing.

  As an example, as shown in FIG. 2, the conductor layer 13 is in a state where a non-formation region (a region where the conductor layer 13 is not formed) is defined on the surface SU facing the measurement target conductor 8 in the hook portion 21. In addition, the insulator layer 12 is interposed between the surface of the detection electrode 11 and the surface of the detection electrode 11 (that is, the surface of the insulator layer 12) while being electrically insulated from the detection electrode 11. Is formed. In this example, the hook portion 21 is formed by forming the concave groove 22 in the detection electrode 11, and the measurement target conductor 8 is accommodated in the concave groove 22, so that the detection probe 1 is attached to the measurement target conductor 8. Hook. For this reason, in this detection probe 1, the entire inner surface (the inner wall surfaces 22 a and 22 b and the bottom wall surface 22 c of the groove 22) of the concave groove 22 is the opposing surface SU.

  In the detection probe 1 of this example, as an example, the entire opposing surface SU (that is, the entire inner surface of the concave groove 22) is defined as the non-formation region for the conductor layer 13, and the entire inner surface of the concave groove 22 is defined. A configuration is adopted in which the conductor layer 13 is formed in almost all other parts of the surface of the detection electrode 11 except for the inner surface while the conductor layer 13 is not formed. With this configuration, in this detection probe 1, while the detection electrode 11 is well shielded by the conductor layer 13 (the influence of the disturbance on the detection electrode 11 is greatly reduced by the conductor layer 13), It is possible to capacitively couple the conductor 8 to be measured and the detection electrode 11 accommodated in each other through a non-formation region of the conductor layer 13 defined in the opposing surface SU (inner surface of the concave groove 22). .

  Further, as described above, since the entire inner surface of the concave groove 22 is the facing surface SU with the conductor 8 to be measured, the portion defined as the non-formation region of the inner surface of the concave groove 22 is the inner surface of the concave groove 22. The inner wall surfaces 22a and 22b and the bottom wall surface 22c constituting the inner wall surface may be at least one wall surface portion. For this reason, it replaces with the structure which prescribes | regulates the whole inner surface of the ditch | groove 22 as a non-formation area | region about the conductor layer 13, and is a part (one any) of each inner wall surface 22a, 22b and the bottom wall surface 22c of the ditch | groove 22 It is also possible to adopt a configuration in which the whole or part of one wall surface, the whole or part of any two wall surfaces, or part of any three wall surfaces) is defined as a non-forming region.

  In this way, only a part of the inner surface of the groove 22 is defined as a non-formation region for the conductor layer 13, and the conductor layer 13 is defined for other portions on the inner surface of the groove 22 except for this part. By adopting the configuration for forming the groove, the measurement object conductor 8 and the detection electrode 11 accommodated in the groove 22 are capacitively coupled through the non-formation region defined on the inner surface of the groove 22, and more Since the surface of the detection electrode 11 can be covered with the conductor layer 13, the shielding effect by the conductor layer 13 can be further enhanced.

  In particular, in the detection probe 1 of this example, as will be described later, when the detection probe 1 is hooked on the measurement target conductor 8, the measurement target conductor 8 is attached to the inner wall surface 22 a of the concave groove 22 by the sheath portion 4. It is configured to be pressed. Therefore, in the detection probe 1 of this example, it is preferable that the entire inner wall surface 22a or a part of the inner wall surface 22a (a portion in the vicinity including the portion to which the measurement target conductor 8 is pressed) be a non-forming region.

  As an example, as shown in FIGS. 1 and 2, the conductor layer 13 has an outer peripheral surface on the base end side of the insulator layer 12 and a base end side of the detection electrode 11 on the base end side of the detection electrode 11. The outer peripheral surface is formed in an exposed state. As an example, in this example, the conductor layer 13 is formed on the surface of the insulator layer 12 with a thickness of, for example, less than 0.1 mm (as an example, about 0.01 mm) using a conductive metal material.

  For example, as shown in FIGS. 1 and 2, the covering layer 14 includes an outer peripheral surface on the base end side of the conductor layer 13, an outer peripheral surface on the base end side of the insulator layer 12, and an outer periphery on the base end side of the detection electrode 11. With the surface exposed, the surface of all other parts of the conductor layer 13 excluding the exposed part is made of, for example, less than 0.1 mm (for example, 0 mm) using a synthetic resin material having electrical insulation. (About 0.05 mm). The coating layer 14 may be formed only on the surface of the distal end portion (the hook portion 21) of the plunger 2 protruding from the distal end opening portion 32 of the sheath portion 4 as described later.

  With the above configuration, in the detection probe 1, as shown in FIGS. 1 and 2, the outer peripheral surface of the detection electrode 11 is exposed from the insulator layer 12 on the proximal end side of the detection electrode 11, and the insulator layer 12 is a conductor. The conductive layer 13 is exposed from the coating layer 14 and is exposed from the layer 13.

  The grip part 3 is formed in a cylindrical shape (in this example, a cylindrical shape as an example) as shown in FIG. 1 by using a synthetic resin material having electrical insulation as an example. The grip portion 3 has a plunger 2 (detection electrode 11 having an insulator layer 12, a conductor layer 13 and a coating layer 14 formed on the surface) on its base end side (base end side of the detection electrode 11). ) Is inserted into the grip portion 3 from one end side (left end side: tip end side in the figure) of the grip portion 3, and the hook portion 21 is fixed while being exposed from the grip portion 3.

  A coaxial cable 7 is connected to the other end side of the grip portion 3 (right end side: rear end side in the figure). Further, in the grip portion 3, the core wire (inner conductor) 7 a of the coaxial cable 7 is electrically connected to a portion exposed from the insulator layer 12 on the proximal end side of the detection electrode 11, and the outer conductor 7 b of the coaxial cable 7. (For example, a shield conductor formed of a braided wire) is electrically connected to a portion of the conductor layer 13 exposed from the coating layer 14. With this configuration, the detection electrode 11 connected to the core wire 7a is shielded almost entirely except for the non-formation region of the conductor layer 13 by the conductor layer 13 defined at the same potential as the external conductor 7b.

  When the outer conductor 7b of the coaxial cable 7 is connected to a portion of the conductor layer 13 exposed from the coating layer 14, the outer peripheral surface on the proximal end side of the core wire 7a and the detection electrode 11 and the outer conductor 7b are electrically connected. It is preferable that the core wire 7a and the outer peripheral surface on the base end side of the detection electrode 11 are covered (shielded) with a shield member defined at the same potential as that of the external conductor 7b while reliably insulating. As this configuration, for example, as shown in FIG. 3, the outer peripheral surface on the proximal end side of the core wire 7a and the detection electrode 11 is covered with an insulating tube 23. In this state, the cylindrical outer conductor 7b of the coaxial cable 7 is It is possible to adopt a configuration in which the insulating tube 23 is passed through the insulating tube 23 as a shield member, and the tip portion is connected to the conductor layer 13 exposed from the gap between the insulating tube 23 and the coating layer 14.

  In addition, as shown in FIG. 4, in the state where the outer peripheral surface on the base end side of the core wire 7 a and the detection electrode 11 is covered with the insulating tube 23, these are hung from the base end side of the plunger 2 to the tip end side of the coaxial cable 7. It is possible to employ a configuration in which the surface is covered with a conductor (such as a conductive film or a conductive thin plate) 24 as a shield member, and the conductor 24 is in electrical contact with the external conductor 7b. By adopting the configuration shown in FIGS. 3 and 4, the surfaces of all other detection electrodes 11 except the non-formation region of the conductor layer 13 defined on the inner surface of the groove 22 and the connection to the detection electrodes 11 are used. Therefore, the exposed core wire 7a of the coaxial cable 7 can be shielded by the conductor layer 13 and the shield member without any gap.

  The sheath part 4 is formed in a cylindrical shape as shown in FIG. 1 by using a synthetic resin material having electrical insulation as an example of the outer shape. Specifically, as an example, the sheath portion 4 has a conical shape in which one end side (the left end side in the figure: the distal end side) is formed with a through hole 31 into which the plunger 2 is slidably inserted. It is formed in a cylindrical shape, and the other end side (right end side: rear end side in the figure) is formed in a cylindrical shape having an inner diameter into which one end side of the grip portion 3 can be inserted. The sheath portion 4 is inserted into one end side of the grip portion 3 (the end portion side where the hook portion 21 of the plunger 2 is exposed) from the cylindrical opening portion on the other end side (opening portion on the other end side). The two hook portions 21 are attached to the grip portion 3 while being inserted into the through holes 31.

  In addition, the sheath portion 4 is in the attached state, and the entire hook portion 21 extends along the axis L of the detection electrode 11 at the tip opening portion (the opening portion 32 on one end side of the through hole 31 in the sheath portion 4. A first position (position shown in FIG. 5) protruding from the tip opening portion 32) and a second position (position shown in FIG. 1; the hook portion 21 as a whole) where the hook portion 21 is immersed in the tip opening portion 32. The position is accommodated in the through-hole 31).

  As an example, the biasing member 5 is configured by a spring coil, is externally fitted to the plunger 2 protruding from the distal end side of the grip portion 3, and is pressed and contracted between the grip portion 3 and the sheath portion 4. The sheath portion 4 is disposed inside the other end side formed in a cylindrical shape. With this configuration, the urging member 5 constantly urges the sheath portion 4 in the second position direction (left direction in FIG. 1) with respect to the grip portion 3.

  As shown in FIG. 8, the main unit 6 includes, as an example, a main power circuit 51, a DC / DC converter (hereinafter also simply referred to as “converter”) 52, a voltage detection unit 53, a resistor 54 for current / voltage conversion, a voltage A generation unit 55, a voltmeter 56, a processing unit 57, and a display unit 58 are provided.

  The main power supply circuit 51 has a positive voltage Vdd and a negative voltage Vss (actual values generated on the basis of the potential of the ground G1 as the first reference potential) for operating each of the components 53 to 58 of the main unit 6. The same DC voltages with different polarities are output. For example, the converter 52 includes an insulated transformer having a primary winding and a secondary winding that are electrically insulated from each other, a drive circuit that drives the primary winding of the transformer, and a secondary winding of the transformer. And a DC converter (not shown) that rectifies and smoothes the AC voltage that is applied, and is configured as an insulated power source in which the secondary side is electrically insulated from the primary side.

  In this converter 52, the drive circuit operates based on the input positive voltage Vdd and negative voltage Vss, and drives the primary winding of the transformer in a state where the positive voltage Vdd is applied, and the AC voltage is applied to the secondary winding. Induces. The direct current converter rectifies and smoothes the alternating voltage. Thereby, from the secondary side of converter 52, positive voltage Vf + and negative voltage Vf− with reference to internal reference potential (second reference potential) G2 on the secondary side are in a floating state (ground G1, positive voltage Vdd and negative voltage Vf−). In a state electrically separated from the voltage Vss). The positive voltage Vf + and the negative voltage Vf− as floating voltages generated in this way are supplied to the voltage detection unit 53 together with the second reference potential G2. The positive voltage Vf + and the negative voltage Vf− are generated as direct current voltages having substantially the same absolute value and different polarities.

  The voltage detection unit 53 includes a current-voltage conversion circuit 53a, an integration circuit 53b, a drive circuit 53c, and an insulation circuit 53d (a photocoupler driven by the drive circuit 53c is illustrated as an example. In the state where the reference potential in the voltage detection unit 53 is defined by the second reference potential G2, the converter can be used. It operates by receiving a positive voltage Vf + and a negative voltage Vf− from 52.

  In the current-voltage conversion circuit 53a, as an example, the non-inverting input terminal is connected to a portion defined by the second reference potential G2 in the voltage detection unit 53 via a resistor (hereinafter also referred to as “connected to the second reference potential G2”). ) And the inverting input terminal is connected to the core wire 7a of the coaxial cable 7 (that is, the detection electrode 11 of the detection probe 1 via the core wire 7a), and the feedback resistor is connected between the inverting input terminal and the output terminal. The first operational amplifier is connected. In the current-voltage conversion circuit 53a, the first operational amplifier operates with the positive voltage Vf + and the negative voltage Vf−, and the voltage V1 of the conductor to be measured 8 and the second reference potential G2 (the voltage signal output from the voltage generator 55). The detection current (current signal) I flowing between the measurement target conductor 8 and the detection electrode 11 at a current value corresponding to the potential difference Vdi due to the potential difference Vdi (refer to FIG. 8). It converts into detection voltage signal V2 and outputs it. In this case, the amplitude of the detection voltage signal V2 changes in proportion to the amplitude of the current signal I.

  For example, the integrating circuit 53b has a non-inverting input terminal connected to the second reference potential G2 via a resistor, an inverting input terminal connected to the output terminal of the first operational amplifier via an input resistor, and feedback. The capacitor includes a second operational amplifier connected between the inverting input terminal and the output terminal. In the integrating circuit 53b, the second operational amplifier operates with the positive voltage Vf + and the negative voltage Vf− and integrates the detection voltage signal V2, whereby the integration signal V3 whose voltage value changes in proportion to the potential difference Vdi. Is generated and output.

  The drive circuit 53c drives the insulation circuit 53d in the linear region according to the level of the integration signal V3, and the driven insulation circuit 53d electrically separates the integration signal V3 to generate a new integration signal (first signal). ) Output as V3a. That is, the voltage detection unit 53 outputs an integration signal V3a indicating the voltage V1 of the measurement target conductor 8 in combination with the detection probe 1.

The current / voltage converting resistor 54 has one end connected to the negative voltage Vss and the other end connected to a corresponding insulating circuit 53d in the voltage detection unit 53 (in this example, the collector terminal of the phototransistor in the photocoupler). ing.

  The voltage generation unit 55 receives and amplifies the integration signal V3a to generate a voltage signal V4 and applies the voltage signal V4 to a portion defined by the second reference potential G2 in the voltage detection unit 53. This voltage signal V4 changes according to the voltage V1 of the conductor 8 to be measured, as will be described later. As a result, the positive voltage Vf + and the negative voltage Vf−, which are floating voltages based on the second reference potential G2, become floating voltages that change according to the voltage of the voltage signal V4.

  As an example, the voltage generation unit 55 includes the second reference potential G2 of the voltage detection unit 53 (the outer conductor 7b of the coaxial cable 7 having the same potential as the second reference potential G2), the detection electrode 11, and the voltage detection unit 53 (current voltage). By forming a feedback loop together with the conversion circuit 53a, the integration circuit 53b, the drive circuit 53c and the insulation circuit 53d (photocoupler in this example), an amplification operation is performed to amplify the integration signal V3a so as to reduce the potential difference Vdi. The voltage signal V4 is generated.

  In this example, as an example, the voltage generation unit 55 includes an amplifier circuit 55a, a phase compensation circuit 55b, and a booster circuit 55c as shown in FIG. Here, the amplification circuit 55a generates the voltage signal V4a by inputting and amplifying the integration signal V3a. In this case, the amplifier circuit 55a generates a voltage signal V4a in which the absolute value of the voltage value changes in accordance with the increase / decrease of the absolute value of the voltage value of the integration signal V3a by an amplification operation. The phase compensation circuit 55b receives the voltage signal V4a, adjusts its phase, and outputs it as the voltage signal V4b in order to stabilize the feedback control operation (prevent oscillation). The booster circuit 55c is configured using a booster transformer as an example, and generates a voltage signal V4 by boosting the voltage signal V4b at a predetermined magnification (by increasing the absolute without changing the polarity). 2 Applied to reference potential G2. The voltmeter 56 measures the voltage signal V4 with reference to the potential of the ground G1, converts the voltage value into digital data, and outputs it as voltage data Dv.

  The processing unit 57 includes a CPU and a memory (both not shown), and executes a voltage calculation process for calculating the voltage V1 of the measurement target conductor 8 based on the voltage data Dv output from the voltmeter 56. To do. Further, the processing unit 57 displays the voltage V1 calculated in the voltage calculation process on the display unit 58 in the form of a table or a graph. For example, the display unit 58 includes a monitor device such as a liquid crystal display.

  When measuring the voltage V <b> 1 of the measurement target conductor 8 using the measurement device MD including the detection probe 1 and the main body unit 6, the tip end portion (the hook portion 21) of the plunger 2 is hooked on the measurement target conductor 8.

  Specifically, first, by applying an external force in the direction of the arrow shown in FIG. 5 to the sheath portion 4 by hand, the urging member 5 moves the sheath portion 4 from the second position shown in FIG. 1 to the first position shown in FIG. By sliding against the urging force (slid in the direction of the arrow), the entire hooking portion 21 of the plunger 2 is projected from the opening 32 of the sheath portion 4 as shown in FIG. Next, as shown in FIG. 6, the measurement target conductor 8 is accommodated in the concave groove 22 of the hook portion 21 (the hook portion 21 is hooked on the measurement target conductor 8).

  In this case, in this detection probe 1, the entire surface of the distal end portion (the entire hook portion 21) of the plunger 2 protruding from the opening portion 32 of the sheath portion 4 is covered with the coating layer 14 having electrical insulation. Even when another conductor is present adjacent to the measurement target conductor 8, the measurement target conductor 8 and the other conductor are short-circuited via the plunger 2 (specifically, the conductor layer 13). The situation has been prevented.

  Subsequently, the hand that applied the external force to the sheath portion 4 is removed. Thereby, since the external force applied to the sheath portion 4 disappears, the inner wall surface 22a of the concave groove 22 and the sheath portion are moved in the arrow direction (second position direction) shown in FIG. 7 by the biasing force of the biasing member 5. 4 until the measurement object conductor 8 is sandwiched between the front edge opening 32 and the edge of the tip opening 32. As described above, the hooking operation of the detection probe 1 onto the measurement target conductor 8 is completed.

  In the detection probe 1, the state in which the hook 21 is hooked on the measurement target conductor 8 is maintained by holding the measurement target conductor 8 in this manner. Therefore, even when the detection probe 1 is released, the capacitance C0 (see FIG. 5) formed between the measurement target conductor 8 and the detection electrode 11 which is important when measuring the voltage V1 of the measurement target conductor 8. 8) is sufficiently avoided. Thus, the detection probe 1 accurately detects the voltage V1 of the measurement target conductor 8 only by capacitively coupling the detection electrodes 11 serving as detection electrodes to each other without directly contacting the measurement target conductor 8. It is configured to be able to function as a so-called non-contact type voltage detection probe.

  In this state, the voltage V1 of the conductor 8 to be measured and the voltage of the second reference potential G2 of the voltage detection unit 53 (the outer conductor 7b of the coaxial cable 7 having the same potential as the second reference potential G2 and the conductor layer of the plunger 2) 13 (that is, when the potential difference Vdi is increased due to the increase of the voltage V1) when the potential difference Vdi with respect to the voltage 13 is increased. In the voltage detection unit 53, the amount of current signal I flowing from the measurement target conductor 8 into the current-voltage conversion circuit 53a via the detection electrode 11 increases. In this case, the current-voltage conversion circuit 53a reduces the voltage value of the output detection voltage signal V2. In the integrating circuit 53b, the current flowing from the output terminal of the second operational amplifier toward the inverting input terminal via the capacitor increases due to the decrease in the detection voltage signal V2. Therefore, the integration circuit 53b increases the voltage of the integration signal V3. As the voltage of the integration signal V3 rises, the transistor of the drive circuit 53c shifts to a deep on state. Thereby, in the insulating circuit 53d (photocoupler), the current flowing through the light emitting diode increases, and the resistance of the phototransistor decreases. Therefore, the voltage value of the integrated signal V3a generated by dividing the potential difference (Vdd−Vss) between the resistance value of the resistor 54 and the resistance value of the phototransistor is decreased.

  In the main unit 6, the voltage generator 55 increases the voltage value of the generated voltage signal V4 based on the integrated signal V3a. In this measurement apparatus MD, the current-voltage conversion circuit 53a, the integration circuit 53b, the drive circuit 53c, the insulation circuit 53d, and the voltage generation unit 55 that form the feedback loop in this way detect an increase in the voltage V1 of the measurement target conductor 8. Then, by executing the feedback control operation for increasing the voltage value of the voltage signal V4, the voltage (voltage of the voltage signal V4) such as the second reference potential G2 of the voltage detection unit 53 is made to follow the voltage V1.

  Further, when the potential difference Vdi increases due to the decrease in the voltage V1, the amount of current of the current signal I that flows out (flows out) from the current-voltage conversion circuit 53a to the measurement target conductor 8 through the detection electrode 11 increases. At this time, voltage detection is performed by the current-voltage conversion circuit 53a and the like constituting the feedback loop performing a feedback control operation opposite to the above-described feedback control operation to reduce the voltage of the voltage signal V4. A voltage (voltage of the voltage signal V4) such as the second reference potential G2 of the unit 53 is made to follow the voltage V1.

  In this way, in the measuring apparatus MD, the feedback control operation for causing the voltage (voltage of the voltage signal V4) such as the second reference potential G2 of the voltage detector 53 to follow the voltage V1 is executed in a short time, and the voltage detector 53, such as the second reference potential G2 (which is also the voltage of the detection electrode 11 due to a virtual short circuit of the first operational amplifier of the current-voltage conversion circuit 53a) is matched (converged) with the voltage V1. The voltmeter 56 measures the voltage value of the voltage signal V4 in real time and outputs voltage data Dv indicating the voltage value. In addition, after the voltage signal V4 once converges to the voltage V1 of the conductor 8 to be measured, each component constituting the feedback loop operates as described above, thereby following the fluctuation of the voltage V1. Therefore, the voltage data Dv indicating the voltage V <b> 1 of the measurement target conductor 8 is continuously output from the voltmeter 56.

  The processing unit 57 receives the voltage data Dv output from the voltmeter 56 and stores it in a memory. Next, the processing unit 57 executes a voltage calculation process, calculates the voltage V1 of the measurement target conductor 8 based on the voltage data Dv, and stores it in the memory. Finally, the processing unit 57 causes the display unit 58 to display the measurement result (voltage V1) stored in the memory. Thereby, the measurement of the voltage V1 of the measuring object conductor 8 by the measuring device MD is completed.

  Subsequently, when measuring the voltage V1 of the other conductor 8 to be measured, first, an external force in the direction of the arrow shown in FIG. 5 is applied to the sheath part 4 by hand, so that the sheath part 4 is viewed from the position shown in FIG. 5 in the direction of the first position shown in FIG. 5 (in the direction of the arrow shown in FIG. 5), between the inner wall surface 22a of the concave groove 22 and the edge of the distal end opening 32 in the sheath portion 4. The clamping state of the conductor 8 to be measured is eliminated. Next, by removing the measurement target conductor 8 from the inside of the concave groove 22, the hooked state of the detection probe 1 on the measurement target conductor 8 is eliminated. As a result, the detection probe 1 can be hooked on the next conductor 8 to be measured.

  Thus, in the detection probe 1 and the measuring device MD provided with the detection probe 1, the tip end of the detection electrode 11 is formed on the hook portion 21, and the core wire 7a of the coaxial cable 7 is connected to the base end portion. The surface of the detection electrode 11 is electrically insulated from the detection electrode 11 in a state where a non-formation region is defined on the surface SU of the hook portion 21 facing the measurement target conductor 8. The conductor layer 13 is formed in this state, and the outer conductor 7 b of the coaxial cable 7 is connected to the conductor layer 13.

  Therefore, according to the detection probe 1 and the measuring device MD provided with the detection probe 1, as long as the hook portion 21 that can be hooked on one conductor as the measurement target conductor 8 can be formed at the distal end portion, a thin rod shape The detection electrode 11 can be formed by a body, and the conductor layer 13 having the above-described configuration is formed on the surface of the detection electrode 11. Since the detection electrode 11 can be shielded while being capable of capacitive coupling, the various detection probes described in the background art exist in close proximity to other conductors that were difficult to mount. Also on the conductor 8 to be measured, the detection electrode 11 can be mounted by hooking the hook portion 21 while reducing the influence of the disturbance on the detection electrode 11 by the conductor layer 13. Result, it is possible to the voltage V1 reliably and easily measured.

  In addition, according to the detection probe 1 and the measurement device MD, the hook portion 21 is formed by providing the concave groove 22 by a simple technique such as cutting at the tip of the thin rod-shaped detection electrode 11. For example, unlike the hooking portion 21 formed by bending the tip of the thin rod-shaped detection electrode 11, the size of the hooking portion 21 can be made approximately the same as the thickness of the detection electrode 11. Therefore, according to the detection probe 1 and the measurement apparatus MD, the voltage V1 can be measured by mounting the measurement probe 8 on the measurement target conductor 8 having a shorter distance from other adjacent conductors.

  In addition, according to the detection probe 1 and the measurement device MD, the measurement target conductor 8 accommodated in the concave groove 22 is moved by the urging force of the urging member 5 to the inner wall surface 22a of the concave groove 22 and the sheath portion. As a result, the state in which the hook 21 is hooked on the measurement target conductor 8 is maintained even when the detection probe 1 is released. The workability of the measurement work for the voltage V1 can be improved.

  Further, when the measurement target conductor 8 is sandwiched between the inner wall surface 22a (tip inner wall surface) of the concave groove 22 and the lip of the distal end opening 32 in the sheath portion 4, the detection probe 1 is used. According to this measuring apparatus MD, as described above, the entire inner wall surface 22a is configured as a non-formation region of the conductor layer 13, and only a part of the inner wall surface 22a (including a portion on which the measurement target conductor 8 is pressed). The conductor layer 13 can be formed in a portion other than this portion on the inner surface of the concave groove 22 by adopting a configuration in which only the portion in the vicinity thereof is a non-forming region. Therefore, according to the detection probe 1 and the measurement apparatus MD, the detection electrode 11 and the measurement target conductor 8 can be capacitively coupled through the non-formation region, and more detection electrodes 11 are formed by the conductor layer 13. Therefore, the shielding effect (disturbance reduction effect) of the conductor layer 13 with respect to the detection electrode 11 can be further enhanced, and the measurement accuracy of the voltage V1 can be further improved.

  Note that the sheath portion 4 and the urging member 5 are omitted when the operation of constantly measuring the voltage V1 by hooking the hook portion 21 on the measurement target conductor 8 while holding the grip portion 3 by hand is omitted. In this configuration, an external force in the direction of pulling down the grip portion 3 from the hand is normally applied to the grip portion 3 from the hand, so that the inner wall surface 22a constituting the inner surface of the hook portion 21 is provided. Mainly contacts the conductor 8 to be measured. Therefore, as described above, by adopting a configuration in which the entire inner wall surface 22a is a non-formation region of the conductor layer 13, or a configuration in which only a part of the inner wall surface 22a is a non-formation region, measurement with the detection electrode 11 is performed. While enabling capacitive coupling with the target conductor 8 through this non-formation region, the shielding effect of the conductor layer 13 on the detection electrode 11 can be further enhanced, and the measurement accuracy of the voltage V1 can be improved.

  In addition, since the detection probe 1 and the measurement apparatus MD are configured to cover the conductor layer 13 with the coating layer 14 having electrical insulation, the distal end portion (pull-out portion) of the plunger 2 protruding from the opening portion 32 of the sheath portion 4 is used. The entire surface of the entire hanging portion 21 is also covered with the coating layer 14. Therefore, according to the detection probe 1 and the measurement apparatus MD, even when another conductor is present adjacent to the measurement target conductor 8, the measurement target conductor 8 and the other conductor are connected to the plunger 2 ( Specifically, the occurrence of a short circuit through the conductor layer 13) can be reliably prevented.

  In the detection probe 1 and the measurement apparatus MD, the detection electrode 11 is exposed from the insulator layer 12 and the conductor layer 13 at the base end portion, and the conductor layer 13 is exposed at the base end portion of the detection electrode 11. It is exposed from the coating layer 14. Therefore, according to the detection probe 1 and the measurement apparatus MD, the connection between the core wire 7a of the coaxial cable 7 and the detection electrode 11 on the proximal end side of the plunger 2 inserted into the grip portion 3, and the coaxial cable 7 The external conductor 7b and the conductor layer 13 can be easily connected.

  Further, according to the detection probe 1 and the measurement device MD, the base end side of the plunger 2 (that is, the detection electrode 11) is set to the same potential as the potential of the outer conductor 7b of the coaxial cable 7 in the grip portion 3. By being configured to be covered with the prescribed shield member (cylindrical outer conductor 7b or conductor 24), all other than the non-formation region of the conductor layer 13 defined on the inner surface of the groove 22 Since the surface of the detection electrode 11 and the core wire 7a of the coaxial cable 7 exposed for connection to the detection electrode 11 can be shielded without any gap, the measurement accuracy of the voltage V1 is further improved. be able to.

  In the above example, the inner wall surfaces 22a and 22b constituting the inner surface of the concave groove 22 are formed so as to be substantially parallel to the reference plane PL orthogonal to the axis L of the detection electrode 11. A configuration in which the inner wall surface 22a positioned on the distal end side of the detection electrode 11 is inclined toward the proximal end portion side of the detection electrode 11 with reference to a reference plane PL orthogonal to the axis L (like the detection electrode 11 shown in FIGS. That is, it is also possible to employ a configuration in which the angle θ1 between the axis L (virtual plane including the axis L) and the inner wall surface 22a is an acute angle. According to this configuration, when the detection probe 1 is hooked on the measurement target conductor 8, it is possible to make it difficult to remove the measurement target conductor 8 from the hook portion 21. Also, as shown in FIG. 11, for example, when the virtual plane PL1 including the entire lip of the tip opening 32 is parallel to the reference plane PL, the inner wall surface 22a of the groove 22 and the sheath portion 4 The distance between the inner wall surface 22a and the virtual plane PL1 including the entire lip of the tip opening 32 when the measurement target conductor 8 is sandwiched between the lip of the tip opening 32 at the bottom of the groove 22 The distance between the inner wall surface 22a and the edge of the tip opening 32 can be removed from the measurement object conductor 8 which can be defined to be shorter as the distance from the wall surface 22c increases. It can prevent more reliably.

  When the configuration in which the inner wall surface 22a is inclined toward the base end side of the detection electrode 11 as described above is adopted, the concave groove of the conductor 8 to be measured is the same as when the concave groove 22 having the configuration shown in FIG. In order to ensure ease of accommodation in the inner wall 22, although not shown, it is preferable that the other inner wall surface 22b facing the inner wall surface 22a is also inclined to the same extent as the inner wall surface 22a.

  Further, while maintaining the effect when the inner wall surface 22a is inclined as described above (the effect that it is difficult to remove the measurement target conductor 8 from the hook portion 21), the measurement target conductor 8 is accommodated in the concave groove 22. 9 and 10, as shown in FIGS. 9 and 10, the inner wall surface 22b located on the base end side of the pair of inner wall surfaces 22a and 22b is placed on the basis of the reference plane PL. A configuration (a configuration in which the angle θ2 between the axis L (virtual plane including the axis L) and the inner wall 22b is inclined more acutely than the angle θ1) can also be employed.

1 Detection probe
2 Plunger
3 Grip part
4 sheath part
5 Biasing member
7 Coaxial cable 7a Core wire 7b Outer conductor
8 Conductor to be Measured 11 Detection Electrode 12 Insulator Layer 13 Conductor Layer 14 Covering Layer 21 Hooking Section 22 Groove 22a, 22b Inner Wall Surface

Claims (11)

The tip portion is formed in a hook portion that is hooked on the conductor to be measured, and the base end portion includes a rod-shaped detection electrode connected to the connection cable,
An insulator layer is formed on the surface of the detection electrode,
A conductor layer electrically insulated from the detection electrode is provided on a surface of the insulator layer excluding a non-formation region defined in at least a part of a surface of the hook portion facing the conductor to be measured. Formed,
The detection electrode is a voltage detection probe configured to be capable of capacitive coupling through the non-formation region and the measurement target conductor hooked on the hook portion.   The voltage detection probe according to claim 1, wherein the hook portion is formed by providing a concave groove at the tip portion along a direction intersecting with the axis of the detection electrode.   Of the pair of inner wall surfaces that are parallel to the intersecting direction in the concave groove and that face each other, the front end side inner wall surface located on the front end side of the detection electrode is based on a reference plane that is orthogonal to the axis. The voltage detection probe according to claim 2, wherein the voltage detection probe is inclined toward the end side.   The base end side inner wall surface located on the base end portion side of the pair of inner wall surfaces is inclined more toward the base end portion side than the distal end side inner wall surface with respect to the reference plane. The voltage detection probe as described.   The voltage detection probe according to claim 3, wherein the non-forming region is defined on the inner wall surface on the tip side.   The voltage detection probe according to claim 1, wherein the conductor layer is covered with a coating layer having electrical insulation. The detection electrode is exposed from the insulator layer and the conductor layer at the base end,
The voltage detection probe according to claim 6, wherein the conductor layer is exposed from the coating layer at the base end portion. A grip part to which the connection electrode is connected and the detection electrode is fixed in a state where the base end side is inserted and the hook part is exposed;
It is formed in a cylindrical shape and is attached to the grip portion in a state where the exposed end portion of the hook portion in the grip portion is inserted from the rear end opening portion, and the hook is formed along the axis of the detection electrode A sheath part slidable between a first position where the part protrudes from the tip opening and a second position where the hooking part is immersed in the tip opening;
The voltage detection according to any one of claims 1 to 7, further comprising a biasing member that is disposed between the grip portion and the sheath portion and constantly biases the sheath portion in the second position direction. probe. The connection cable is composed of a coaxial cable,
The voltage according to claim 8, wherein the base end portion is directly connected to the core wire of the coaxial cable and covered with a shield member defined to have the same potential as the potential of the outer conductor of the coaxial cable in the grip portion. Detection probe. A voltage detection probe according to any one of claims 1 to 9,
A main body unit connected to the voltage detection probe via the connection cable, the core wire comprising a coaxial cable directly connected to the base end ; and
Disposed within said main body unit, a voltage detection unit that outputs a voltage signal that changes according to the voltage and detects the core wire and the voltage of the measurement target conductor through the detection electrode of the coaxial cable,
A voltage generator disposed in the main body unit and generating a voltage that follows the voltage of the conductor to be measured based on the voltage signal and applied to an outer conductor of the coaxial cable;
A processing unit disposed in the main unit and measuring the voltage of the measurement target conductor based on the voltage generated by the voltage generation unit;
The voltage detector is a measuring device that operates with a floating voltage based on the potential of the voltage generated by the voltage generator. The voltage detection unit has a current-voltage conversion circuit configured with an operational amplifier,
In the operational amplifier, an inverting input terminal is connected to the base end via the core wire, and a non-inverting input terminal is defined by the potential of the voltage generated by the voltage generation unit,
The measuring device according to claim 10, wherein an outer conductor of the coaxial cable is defined by the potential of the voltage generated by the voltage generation unit and is connected to the conductor layer on the voltage detection probe side.

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