JP4410150B2 - Current detector - Google Patents

Description

  The present invention is, for example, for detecting a current with respect to a relatively large current such as a current flowing through a central conductor of a GIS (gas insulated switchgear) or a current flowing through a heating coil of a high-frequency induction heating device. The present invention relates to a current detector having a detection unit using the principle of Rogowski coil.

  As a conventional current detector, a Rogowski coil is composed of an electrically insulating and flexible tube and a conductive wire wound around the outer peripheral surface of the tube at a predetermined interval, and is detachable from the current path. There is a current detector to be wound and joined. (For example, refer to Patent Document 1).

JP 2002-181850 A (FIG. 1)

  Since the conventional current detector described above has a structure in which the distal end portion of the tube is detachably fitted and joined, a gap is easily generated between the start and end of winding of the conductive wire. That is, even if it is wound and joined to the current path, a slight gap is required at the joint in order to connect the coaxial cable to the conductive wire and draw it out, and the gap dimension tends to become unstable. Therefore, there is a problem that the measurement accuracy of the detection current is lowered. In addition, depending on the gap size and the like, there is a problem that the current cannot be detected stably because the tip of the tube is not securely joined and locked. In addition, there is a problem that it is easily affected by a magnetic field such as other adjacent current lines.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to obtain a current detector with high measurement accuracy and capable of stable current detection.

A current detector according to the present invention includes a detector based on the principle of a Rogowski coil formed so as to be detachably wound around a current wire to be measured, and an output signal connected to an output line of the detector. In the apparatus including a signal processing unit for processing, the detection unit passes a conductive wire through an insulating tube formed of a flexible insulating material, and spirally coils on the outer peripheral surface of the insulating tube. the wound by connecting one ends and the coil of the conductive wire and each output line and the other end of the conductive wire and the coil, the connecting portion of the coil and the conductive wire to one end surface of the detecting unit A fitting portion for fitting is provided, and a fitting portion for fitting the lead-out portion of the output line is provided on the other end surface of the detection portion, and the connection portion and the lead-out portion are fitted, respectively. Current wire to be measured Configured such that one end face and another end face of the can closely joined when wound, and closely joined state of the two end faces provided with a holding member that holds and retains a close bonding state reliably It is comprised as follows.

  According to this invention, the fitting portion for fitting the connecting portion of the conductive wire and the drawing portion of the output wire is provided on the end surface of the tube, that is, the end surface of the detecting portion, and the connecting portion and the drawing portion are provided in the fitting portion. By fitting, the connection portion of the coil and the conductive wire and the lead-out portion of the output wire do not protrude, so that the end face can be reliably brought into close contact when wound around the current wire to be measured. In addition, since the close state is held by the holding member, the close state does not change. Therefore, the measurement accuracy is stable, and a highly accurate current detector can be obtained. Furthermore, since the magnetic shielding member is disposed on the end face portion of the close detection unit, the influence of the magnetic field such as other current lines can be suppressed and the current of the current line to be measured can be measured with high accuracy. It has a great effect.

Embodiment 1 FIG.
1 is an external perspective view of a current detector according to Embodiment 1 of the present invention, FIG. 2 is an external perspective view showing a state before or after winding the holding member of FIG. 1 around a current wire to be measured, and FIG. 1 is a cross-sectional view taken along line AA in FIG. 1, FIG. 4 is a cross-sectional view taken along line BB in FIG. 1, FIG. 5 is a perspective view of one end of a tube wound with a coil, and FIG. It is a perspective view of an end.
In these drawings, the current detector 100 includes a detection unit 20 that is annularly wound around the current line 18 to be measured, a holding member 30 that holds both ends of the detection unit 20 in close contact with each other, and a detection unit. The signal processing unit 40 is connected to the output lines 5 and 6 of the unit 20 and processes output signals. The core of the detection unit 20 has insulation and flexibility, and is formed of, for example, an insulator having a rubber hardness of 30 to 60 degrees defined by JIS (Japanese Industrial Standard) in plastic elastomer or silicon rubber. A tube 1 is disposed, and a coil 2 having an insulating coating is wound around the outer peripheral surface of the tube 1 in a spiral shape. In this winding, the number of turns is increased as much as possible in order to increase the detection degree. For this reason, it is usually made tightly wound. One end face of the coil 2 is connected to the conductive wire 3 penetrating through the central portion of the tube 1 by a connecting portion 4 as shown in FIGS. 3 and 5, and the other end face of the coil 2 is used as the output line 5. The other end of the conductive wire 3 is also drawn out as an output line 6. This configuration forms a Rogowski coil.

On one end face 1a of the tube 1, a fitting portion 1b (shown in FIG. 5) for fitting the connection portion 4 of the coil 2 and the conductive wire 3 is disposed in a groove shape. The other end face 1c of the tube 1 is provided with a fitting portion 1d (shown in FIG. 6) into which the lead portion 3a of the conductive wire 3 is fitted. The close contact portion 15 between the end surface 1a and the end surface 1c of the tube 1 is electrically insulated from the coil 2 and the conductive wire 3 on the one end surface 1a side, and the coil 2 and the conductive wire 3 on the other end surface 1c side. Insulating protective sheet 14 (shown in FIG. 3) is provided. The protective sheet 14 may be either one of the end surface 1a and the end surface 1c of the tube 1, but is preferably disposed on both. In the above description, the fitting portion 1b is provided on one end face 1a of the tube 1 and the fitting portion 1d is provided on the other end face 1c. However, the coil 1 is electrically connected to one end face 1a or the other end face 1c. A deep groove-like fitting portion capable of fitting the connecting portion 4 of the line 3 and the lead portion 3a of the output line 6 may be formed. However, in any case, it is desirable to make the fitting portion shallow as long as the connection portion between the coil and the conductive wire and the lead-out portion 3a of the output wire do not protrude from the end face.

  In the detection unit 20, the outer periphery of the coil 2 is formed with an outer diameter of 15 mm to 20 mm by an insulating layer or a shield layer as shown in FIG. That is, the first insulating layer 7 is covered with the coil 1 wound around the tube 1, and the upper layer is covered by the electric field shield 8, the second insulating layer 9, the magnetic field shield 10, and the covering layer 11. It is disguised. Note that the first insulating layer 7, the second insulating layer 9, and the covering layer 11 are each formed using a flexible insulating material. The electric field shield 8 is preferably made of a material that has electrical conductivity and does not impair the flexibility of the tube 1. For example, a cylindrical copper net or a foil-like copper tape can be wound. The magnetic field shield 10 is desirably made of a material that has a relatively large relative magnetic permeability and does not impair the flexibility of the tube 1. For example, a foil-like amorphous alloy may be wound. In the arrangement of the first insulating layer 7, the coil 2 is adhered to the tube 1 to such an extent that the flexibility is not impaired in order to prevent the coil 2 from being disturbed, uneven winding, non-adhesion, etc., particularly near the end face. It may be.

Next, the holding member 30 that wraps and holds the detection unit 20 around the current wire 18 to be measured will be described. That is, a socket-type holding member 13 made of, for example, a thermoplastic molding resin material is fixed to one end of the detection unit 20 by adhesion, and a plug-type holding member 12 is fixed to the other end. The socket-type holding member 13 is provided with an engaging portion 13a formed by a concave groove on the inner surface, and the plug-type holding member 12 is provided with a convex engaging portion 12a. The end surfaces of the detection part are configured to be held in close contact with each other by the engagement of both the engaging parts 12a and 13a of the holding member. Note that a plurality of engaging portions 12a and engaging portions 13a may be formed, and convex portions and concave portions may be formed in a spiral shape.

  In the detection unit 20 having the above-described configuration, the winding start and end of the coil 2 are often difficult to tightly wind at portions close to the end surface 1a and the end surface 1c in the winding process. Therefore, when the detection unit 20 is wound around the current wire 18 to be measured and the engaging portion 12a and the engaging portion 13a are engaged, uneven winding may occur at the beginning and end of winding adjacent to each other. This winding unevenness causes a difference in the influence of the external magnetic field on the portion where there is no winding unevenness when detecting the magnetic field to be measured by the measured current line 18, and an error occurs in the induced electromotive voltage. There is a problem that a measurement error occurs due to this difference, that is, the influence of an external magnetic field other than the magnetic flux due to the current line 18 to be measured. In the present invention, as a means for solving this problem, the magnetic shielding plate 16 is wound around the end face of the joined detection unit 20 in a state where the detection unit 20 is wound around the current wire 18 to be measured. Although there are various means for this winding, in this embodiment, as shown in FIG. 3, a magnetic shielding plate 16 made of an iron plate is integrally inserted in the socket-type holding member 13. The magnetic shielding plate 16 can effectively suppress the occurrence of measurement errors due to the intrusion of an external magnetic field. The magnetic shielding plate 16 may be made of the same material as the magnetic field shield 10.

The current detector 100 according to the first embodiment of the present invention configured as described above is wound around the current wire 18 to be measured in a ring shape, and the magnetic flux changes due to the current change flowing through the current wire 18 to be measured. The coil 2 detects the induced electromotive voltage and inputs it to the signal processing unit 40 constituting the current measuring circuit via the output lines 5 and 6. Note that the detection unit 20 of the current detector 100 may be wound around the current wire to be measured 18 a plurality of times. Further, the current wire 18 to be measured may be wound around the detection unit 20 of the current detector 100 a plurality of times.

According to the first embodiment of the present invention configured as described above, the coil 2 is wound in close contact with the end surface of the tube 1, and from the end surfaces 1 a and 1 c of the tube 1 to the coil 2, the conductive wire 3, In the state where the connecting portion 4 does not protrude and the both end faces 1a and 1c of the tube 1 are in contact with each other,
The socket-type holding member 12 and the plug-type holding member 13 hold the joints of the end faces of the detection portion closely to each other, so that errors due to misalignment or the like can be suppressed. Further, since the magnetic shielding plate 16 is integrally inserted into the holding member 30, magnetic noise from the outside can be reduced with an inexpensive structure.

Furthermore, since the holding member 30 is easy to attach and detach, and the tube 1 is formed using an insulator having a rubber hardness of 30 to 60 degrees such as silicon rubber having an appropriate elastic force, the coil 2 is disturbed and unevenly wound. Since the coil 2 is stably fixed, productivity is improved, flexibility is maintained, and the detection unit 20 can be easily attached and detached.

Embodiment 2. FIG.
7 is an external perspective view of the current detector in the second embodiment, FIG. 8 is an enlarged view showing the main part of the current detector in FIG. 7, and FIG. 9 is the position of the auxiliary magnetic shielding member in the current detector in FIG. It is an external appearance perspective view when moving.
In the second embodiment, as shown in FIG. 7, in the state where the detection unit 20 is wound around the current wire 18 to be measured, the holding member 30 having the socket-type holding member 13 in which the magnetic shielding plate 16 is inserted is used. The auxiliary magnetic shielding member 31 is slidably disposed at an opposing position across the current line 18 to be measured. As shown in FIG. 8, the auxiliary magnetic shielding member 31 includes a base 31a formed of a molded insulating material having a rubber hardness of 30 to 60 degrees as defined by JIS (Japanese Industrial Standard) in plastic elastomer or silicon rubber. For example, it is configured in a cylindrical shape with a shielding plate 31b made of an iron plate. In this case, the shielding plate 31b is integrally inserted into the base 31a, and the base 31a can be stopped in a state of being fitted to the detection unit 20 and moved to a desired position.

  The current detector according to the second embodiment configured as described above is wrapped around the current wire 18 to be measured in the same manner as the current detector according to the first embodiment described above. The coil 2 detects an induced electromotive voltage due to a change in magnetic flux due to a change in the flowing current, and outputs the induced electromotive voltage to the signal processing unit 40 configuring the current measurement circuit via the output lines 5 and 6.

  In general, in a current detector that detects the current flowing through the current line 18 to be measured by winding the detection part 20 around the current line 18 to be measured, the coil 2 of the detection unit 20 is annularly formed around the tube 1. Since it is wound, the position of the holding member 30 having the socket-type holding member 13 into which the magnetic shielding plate 16 is inserted when the detection unit 20 receives an external magnetic field (shown in FIG. 7), and the auxiliary magnetic shielding member At the position 31, since the winding direction of the coil 2 is reversed, the electromotive force in the coil 2 due to the external magnetic field is canceled, but the current detection has a structure in which both ends of the tube 1 around which the coil 2 is wound abuts. In the case, the coil 2 is not uniformly wound in the vicinity of the close contact portion 15 (shown in FIG. 3), so that an imbalance occurs in the detection capability of the external magnetic field, and the external magnetic field cannot be canceled. From the above, the current detector according to the second embodiment is shielded by the auxiliary magnetic shielding member 31 in the vicinity of the close contact portion 15 where the coil 2 is not wound uniformly and the opposing portion (shown in FIG. 9). This suppresses the influence of an external magnetic field.

  The current detector according to the second embodiment configured as described above has a position that is 180 ° opposite to the position of the holding member 12 or an arbitrary position when it is wound around the current line 18 to be measured in an annular shape. By moving the auxiliary magnetic shielding member 31 to the first, the influence of the external magnetic field is suppressed, and stable current detection with high measurement accuracy can be performed.

1 is an external perspective view of a current detector according to Embodiment 1 of the present invention. External perspective view showing a state before or after the detector is wound around the current wire to be measured AA line cross-sectional view of the detection unit in FIG. BB sectional view of the detection unit in FIG. Perspective view of one end of a tube wound with a coil Perspective view of the other end of the tube around which the coil is wound External perspective view for explanation of a current detector according to Embodiment 2 of the present invention The principal part enlarged view of the magnetic shielding member 31 in FIG. 7 is an external perspective view when the position of the auxiliary magnetic shielding member in FIG. 7 is moved.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tube 1b, 1d Insertion part 2 Coil 3 Conductive wire 3a Lead-out part 4 Connection part 5,6 Output line 12 Plug type holding member 13 Socket type holding member 12a, 13a Engagement part 18 Current line to be measured 20 Detection part 30 Holding Member 40 Signal processor 100 Current detector

Claims (5)

A detector equipped with a Rogowski coil principle formed so as to be detachably wound around the current line to be measured, and a signal processor connected to the output line of this detector to process the output signal In the above, the detecting section allows the conductive wire to pass through an insulating tube formed of a flexible insulating material, and spirally winds a coil around the outer peripheral surface of the insulating tube to end one end of the conductive wire. And connecting one end of the coil to the conductive wire and the other end of the coil as output lines, respectively , and providing a fitting portion for fitting the connection portion of the coil and the conductive wire on one end surface of the detection unit , When the detecting portion is wound around the current wire to be measured by providing a fitting portion for fitting the drawing portion of the output line on the other end surface of the detecting portion and fitting the connecting portion and the drawing portion, respectively. one end surface and other Configured so that the end face of the can closely joined, and a current detector, characterized in that a holding member for a close bonding state of the end surfaces to hold. The holding member is provided with a socket-type holding member having an engaging portion on the inner surface at one end of the detecting portion, and provided with a plug-type holding member having an engaging portion on the outer surface at the other end of the detecting portion. The current detector according to claim 1, wherein the current detector is configured so as to be able to maintain the joined state of the end face of the detection portion by the engagement.   3. The current detector according to claim 1, wherein a magnetic shielding plate is wound around an end surface portion of the detection unit to be joined in a state where the detection unit is wound around the current wire to be measured.   4. The current detector according to claim 3, wherein the socket-type holding member is formed of a thermoplastic molding resin, and a magnetic shielding plate is integrally provided on the socket-type holding member.   In the state where the detection unit is wound around the current wire to be measured, an auxiliary magnetic shielding member adapted to be installed at a desired position with respect to the end surface portion of the detection unit to be joined is provided in the detection unit. The current detector according to claim 3 or 4.

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