JP2019102510A - Current transformer - Google Patents

Abstract

To provide a current transformer capable of generating a bias magnetic field by a simple configuration without using an external power source or the like.SOLUTION: A current transformer comprises: a core part (12) made of a soft magnetic material; secondary-side wiring (18) wound around the core part; a shunt resistor (22) bridge-connected between both ends of the secondary-side wiring; at least one magnet (14) which is fittable to the core part and generates a magnetic field inside the core part; and a cut piece (16) which is fittable to the core part and is made of the same material as that of the core part. The core part includes: a cutout portion (120) which is a portion without the soft magnetic material; and a remainder portion (126) which is a portion other than the cutout portion. The cut piece and the magnet are interchangeably fitted into the cutout portion.SELECTED DRAWING: Figure 1

Description

  The techniques disclosed herein relate, for example, to current measurements in characterizing power devices.

  When measuring the current for the electrical property evaluation of the power device, a current transformer (i.e., a current transformer) is mainly used (see, for example, Patent Document 1).

  In the current transformer, since the current corresponding to the current flowing in the primary side wire flows through the secondary side wire, the current flows through the primary side wire by measuring the voltage drop of the shunt resistor connected to both ends of the secondary side wire The current value can be calculated indirectly.

  However, in the measurement of the current value using a current transformer, there is a disadvantage that when the DC component of the current continues to flow for a fixed time or more, the core portion is magnetically saturated and the current value can not be measured. In particular, when the current to be measured is a large current, the defect becomes remarkable.

  Then, the method of suppressing said magnetic saturation is known by producing a bias magnetic field in a core part.

Japanese Patent Application Laid-Open No. 05-029167

  However, when a bias magnetic field is generated by the above method, it is necessary to prepare in advance a power supply for bias, a limiting resistor, a cable, and the like.

  The technology disclosed in the present specification was made to solve the problems as described above, and a current transformer capable of generating a bias magnetic field with a simple configuration that does not use an external power supply or the like. The purpose is to provide

  According to a first aspect of the technology disclosed in the present specification, a core portion made of a soft magnetic material and disposed so as to surround the primary side wire along at least a part of the circumferential direction of the primary side wire; A secondary side wire wound around at least a part of the core portion, a shunt resistor connected across both ends of the secondary side wire, attachable to the core portion, and inside the core portion At least one magnet for generating a magnetic field, and a section attachable to the core and made of the same material as the core, the core being provided with the material of the soft magnetic material It has a defect which is a non-portion and a remaining part which is not the defect, and the section and the magnet are fitted exchangeably in the defect.

  According to a first aspect of the technology disclosed in the present specification, a core portion made of a soft magnetic material and disposed so as to surround the primary side wire along at least a part of the circumferential direction of the primary side wire; A secondary side wire wound around at least a part of the core portion, a shunt resistor connected across both ends of the secondary side wire, attachable to the core portion, and inside the core portion At least one magnet for generating a magnetic field, and a section attachable to the core and made of the same material as the core, the core being provided with the material of the soft magnetic material The cut-off part which is a non-part and the remaining part which is a part which is not the cut-off part are provided, and the section and the magnet are fitted exchangeably in the cut-off part. According to such a configuration, a bias magnetic field can be generated as needed by the magnet exchangeably fitted to the defect portion without using an external power supply or the like.

  The objects, features, aspects and advantages of the technology disclosed in the present specification will become more apparent from the detailed description given below and the accompanying drawings.

It is the schematic which illustrates the structure for implement | achieving a current transformer regarding 1st Embodiment. It is the schematic which illustrates the structure of a current transformer in the state in which the primary side wiring was let through the wiring hole. It is a conceptual diagram which illustrates the appearance of the bias magnetic field formed inside the core when the magnet is fitted into the gap. It is the schematic which illustrates the structure of a current transformer in the state in which the primary side wiring was let through the wiring hole. It is the schematic which illustrates the structure for implement | achieving a current transformer regarding 2nd Embodiment. It is the schematic which illustrates the structure of a current transformer in the state in which the primary side wiring was let through the wiring hole. It is a conceptual diagram which illustrates the appearance of the bias magnetic field formed inside the core part when a magnet is inserted in a counterbore part. FIG. 8 is an enlarged view illustrating a bias magnetic field illustrated in FIG. 7; It is the schematic which illustrates the structure for implement | achieving a current transformer regarding 3rd Embodiment. It is the schematic which illustrates the structure for implement | achieving a current transformer regarding 4th Embodiment. It is the schematic which illustrates the structure for implement | achieving a current transformer regarding 5th Embodiment. It is a conceptual diagram which illustrates the mode of the bias magnetic field formed inside the core part at the time of the magnet being inserted in the counterbore part. FIG. 5 is a schematic view illustrating the configuration of a current transformer. It is a conceptual diagram which illustrates the characteristic of the core part of the current transformer which consists of a soft magnet. It is the schematic which illustrates the structure of the current transformer which produces a bias magnetic field. FIG. 10 is a schematic view illustrating the structure of another current transformer that generates a bias magnetic field.

  Hereinafter, embodiments will be described with reference to the attached drawings.

  Note that the drawings are schematically illustrated, and omission of the configuration or simplification of the configuration may be made as appropriate for the convenience of description. In addition, the interrelationships among sizes and positions of configurations and the like shown in different drawings are not necessarily accurately described, and may be changed as appropriate.

  Moreover, in the description shown below, the same code | symbol is attached | subjected and shown to the same code | symbol, and suppose that it is the same also about those names and functions. Accordingly, detailed descriptions about them may be omitted to avoid duplication.

  Also, in the description described below, specific positions and directions such as “upper”, “lower”, “left”, “right”, “side”, “bottom”, “front” or “back” Although the terms used are sometimes used, these terms are used for the sake of convenience to facilitate understanding of the contents of the embodiment, and are not related to the direction in which they are actually implemented. It is not a thing.

First Embodiment
The current transformer according to the present embodiment will be described below. For convenience of explanation, first, the configuration of the current transformer and the magnetic saturation will be described.

  FIG. 13 is a schematic view illustrating the configuration of the current transformer. As illustrated in FIG. 13, the current transformer includes a core portion 12F, a secondary side wire 18 at least partially wound around the core portion 12F, and output terminals 20 at both ends of the secondary side wire 18; And a shunt resistor 22 connected across the output terminals 20. The core portion 12F is disposed in a donut shape along the circumferential direction of the primary side wiring 24.

  When a current (that is, a current to be measured) starts to flow in the primary side wiring 24, a magnetic flux fluctuation tends to occur inside the core portion 12F, but a current flows in the secondary wiring 18 so as to cancel the magnetic flux fluctuation. . Specifically, with respect to the current flowing through the primary side wiring 24, a current that is a fraction of the number of turns flows through the secondary side wiring 18. Here, the number of turns is the number of turns of the secondary side wiring 18 around the core portion 12F.

  Then, a voltage is generated in the shunt resistor 22 in accordance with the current flowing through the secondary side wiring 18. By detecting the generated voltage using, for example, an oscilloscope or the like, the value of the current flowing through the primary side wiring 24 can be measured indirectly.

  The above current transformer does not require a driving power supply, and can measure the current flowing through the primary side wiring 24 easily without contact.

  However, in the measurement of the current value using a current transformer, there is a disadvantage that when the DC component of the current continues to flow for a fixed time or more, the core portion is magnetically saturated and the current value can not be measured. In particular, when the current to be measured is a large current, the defect becomes remarkable.

Immediately after the current starts to flow in the primary side wiring 24, a current of 1 / N _{2 of the} primary side wiring 24 flows in the secondary side wiring 18, and the magnetomotive force of the current in the primary side wiring 24 and the secondary side wiring 18 And the magnetomotive force of the current at. Therefore, no magnetic flux is generated inside the core portion 12F. Here, N ₂ represents the number of times the secondary side wire 18 is wound around the core portion 12F. The current in the primary side wiring 24 is also referred to as a current to be measured.

  However, as time passes, the current flowing through the secondary wiring 18 attenuates with respect to the current to be measured. The decay rate per unit time is called droop.

  Therefore, the magnetomotive force due to the current to be measured and the magnetomotive force due to the current in the secondary side wiring 18 become unbalanced. As a result, magnetic flux is generated inside the core portion 12F.

  Since the current in the secondary wiring 18 is attenuated with the passage of time, the difference between the magnetomotive force due to the current to be measured and the magnetomotive force due to the current in the secondary wiring 18 is further increased. The internal magnetic flux also increases with the passage of time.

  For example, a unit step-like current represented by the following formula (1) is applied to the primary side wiring 24.

Here, U (t) represents a unit step function. Further, I ₀ is the peak _value of the unit-step-like current to be measured.

  Then, a current represented by the following formula (2) flows to the secondary side wiring 18 in response to the above current.

Here, L ₂ represents the inductance of the secondary wire 18 when you open the primary side wiring 24. Further, N ₁ represents the number of turns of the primary side wiring 24, and N ₂ represents the number of turns of the secondary side wiring 18. Also, R is the resistance value of the shunt resistor 22.

  Here, the primary side wire 24 and the secondary side wire 18 of the current transformer are tightly coupled. Therefore, the magnetic flux generated inside the core portion 12F can be expressed by the following equation (3).

Here, R _m represents the magnetic resistance inside the core portion 12F.

Then, when N ₁ = 1, the following equation (4) can be derived from the above equation (2) and the above equation (3).

  As shown in the above equation (4), no magnetic flux is generated inside the core 12F immediately after the current to be measured starts to flow (ie, t = 0). However, as time passes, magnetic flux is generated inside the core portion 12F.

  At this time, the magnetic flux generated inside the core portion 12F increases as the measured current increases and as the application time of the DC component of the measured current increases.

  Here, when the magnetic flux generated inside the core portion 12F exceeds a threshold value, the core portion 12F causes magnetic saturation. When magnetic saturation occurs, the magnetic resistance of the core portion 12F rapidly increases. Therefore, the magnetic flux leaks to the outside of the core portion 12F. The point where this magnetic saturation occurs is quantitatively represented by the value of the current to be measured and the time for which the current to be measured is applied, and is referred to as an IT product.

  In the case of measuring the current value flowing to the primary side wiring 24 using a current transformer, it is premised that the magnetic flux does not leak from the inside of the core portion 12F to the outside (that is, close coupling). When magnetic saturation occurs, the coupling is not tightly coupled, and the output voltage of the shunt resistor 22 becomes 0V. Then, the measured current can not be detected.

FIG. 14 is a conceptual diagram illustrating the characteristics of the core portion of the current transformer made of a soft magnetic material. In FIG. 14, the vertical axis represents the magnetic flux φ [Wb] or the magnetic flux density B [Wb / m ² ], and the horizontal axis represents the magnetic field strength H [A / m].

  In the range between point B and point C in FIG. 14, the magnetic flux or magnetic flux density also increases as the strength of the magnetic field increases. However, when the magnetic flux φ exceeds a certain threshold value, the differential permeability (ie, ΔB / ΔH) decreases sharply.

  In FIG. 14, when the range between the point B and the point C is deviated, the differential permeability decreases sharply. Outside the range between the points B and C in FIG. 14, magnetic saturation occurs and the magnetic flux leaks to the outside of the core portion.

  That is, the current transformer needs to be used so that the magnetic flux φ of the core portion falls within a range between points B and C in FIG. 14 (hereinafter also referred to as a linear region).

  Therefore, a method of suppressing magnetic saturation by generating a bias magnetic field is known.

  FIG. 15 is a schematic view illustrating the structure of a current transformer that generates a bias magnetic field. As illustrated in FIG. 15, in addition to the configuration illustrated in FIG. 13, the current transformer is wound with a cable 30 for generating a bias magnetic field separately from the secondary side wiring 18 in the core portion 12F. Be An input terminal 32 is connected to both ends of the cable 30, and a power supply 34 and a limiting resistor 36 of the power supply 34 are connected in series across the two input terminals 32.

  In the above configuration, a magnetic field is generated in advance inside the core portion 12F by supplying a current to the cable 30. The direction of the magnetic field generated at this time is opposite to the magnetic field generated when the current to be measured flows.

  Specifically, assuming that the magnetic field generated inside core portion 12F when the current to be measured flows is on the right side of point A in FIG. 14 (that is, the side where the strength H of the magnetic field is large), a bias magnetic field is generated. By this, the strength H of the magnetic field inside the core portion 12F is located near the point C in the default state (that is, the state where the current to be measured does not flow).

  If the current to be measured flows in this state, the linear region from point C to point B can be efficiently used, and therefore the IT product can be increased.

  FIG. 16 is a schematic view illustrating the structure of another current transformer that generates a bias magnetic field. In the case illustrated in FIG. 16, the power supply 34 and the limiting resistor 36 are connected in series across the two output terminals 20. The shunt resistor 22 is connected in parallel to the power supply 34 and the limiting resistor 36. That is, the secondary side wiring 18 is also used as a cable for generating a bias magnetic field.

<About the configuration of the current transformer>
FIG. 1 is a schematic view illustrating a configuration for realizing a current transformer according to the present embodiment. As illustrated in FIG. 1, the current transformer includes a core portion 12 made of a soft magnetic material, a secondary side wire 18 at least partially wound around the core portion 12, and output terminals at both ends of the secondary side wire 18. 20, a shunt resistor 22 connected across two output terminals 20, a magnet 14, and a section 16 made of the same material as the core section 12.

  The core portion 12 is disposed to at least partially surround the primary side wiring along the circumferential direction of the primary side wiring. In addition, the said arrangement | positioning relationship is implement | achieved by passing primary side wiring through the wiring hole 122 of the core part 12. FIG.

  The core portion 12 includes a gap portion 120 which divides the core portion 12 in the circumferential direction of the primary side wiring, and a remaining portion 126 which is a portion other than the gap portion 120. That is, the remaining portion 126 of the soft magnetic body is not disposed in the portion which is the gap portion 120.

  The magnet 14 and the piece 16 both have the same dimensions as the gap 120 and are detachably fitted to the gap 120. When measuring the current flowing to the primary side wiring by the current transformer, the magnet 14 or the piece 16 is fitted in the gap 120.

  FIG. 2 is a schematic view illustrating the configuration of the current transformer in a state where the primary side wiring is passed through the wiring hole. As illustrated in FIG. 2, the core portion 12 is disposed along the circumferential direction of the primary side wiring 24 so as to surround the primary side wiring 24.

  Further, in FIG. 2, the magnet 14 is fitted into the gap 120. By fitting the magnet 14 into the gap 120, a bias magnetic field is generated inside the core 12.

  FIG. 3 is a conceptual view illustrating the state of the bias magnetic field formed inside the core when the magnet is fitted into the gap. In FIG. 3, a magnetic flux 26 indicating a bias magnetic field is illustrated. The magnetic flux 26 in FIG. 3 is formed in the counterclockwise direction inside the core 12 and goes around the core 12 and enters the opposite pole.

  When a current (that is, a current to be measured) flows through the primary side wiring 24 along the current direction 28 of FIG. 2 in the state where the bias magnetic field illustrated in FIG. 3 is generated, the direction to cancel the bias magnetic field by the current to be measured The magnetic field of

  According to the above configuration, by generating a bias magnetic field using magnet 14, the strength H of the magnetic field inside core portion 12 is in a default state (that is, a state in which no current to be measured flows), for example , And can be located near point C in FIG. Then, if the current to be measured flows in this state, for example, the linear region from point C to point B in FIG. 14 can be efficiently used, and therefore the IT product can be increased.

  FIG. 4 is a schematic view illustrating the configuration of the current transformer in a state where the primary side wiring is passed through the wiring hole. Further, in FIG. 4, the section 16 is fitted into the gap 120. By fitting the section 16 into the gap 120, a current transformer having the core 12 in which no bias magnetic field is generated is obtained.

  For example, when the current to be measured flows in only one direction, the magnet 14 is fitted into the gap 120 to measure the current to be measured as illustrated in FIG. 2, while the current to be measured is bidirectional. In the case where the current flows, as shown in FIG. 4, the section 16 is fitted in the gap 120 so that the magnetic flux does not leak from the gap 120, and the current to be measured is measured. That is, although the current direction 28 is shown in FIG. 4, even when the current to be measured flows in the reverse direction of the current direction 28, the configuration illustrated in FIG. 4 can be applied.

  Further, by preparing a plurality of magnets 14 having different magnetic forces and fitting any one of the magnets 14 into the gap portion 120, the strength of the bias magnetic field formed inside the core portion 12 is adjusted. Can.

Second Embodiment
The current transformer according to the present embodiment will be described. In the following description, constituent elements similar to the constituent elements described in the embodiments described above are illustrated with the same reference numerals, and the detailed description thereof is appropriately omitted.

<About the configuration of the current transformer>
FIG. 5 is a schematic view illustrating the configuration for realizing the current transformer according to the present embodiment. As illustrated in FIG. 5, the current transformer includes a core portion 12A, a secondary side wire 18 at least partially wound around the core portion 12A, and output terminals 20 at both ends of the secondary side wire 18; A shunt resistor 22 connected across the output terminals 20, a magnet 14A, and a section 16A made of the same material as that of the core portion 12A are provided.

  The core portion 12A includes a counterbore portion 124 and a remaining portion 126A which is a portion other than the counterbore portion 124.

  The magnet 14A and the section 16A both have the same dimensions as the counterbore portion 124 and are fitted into the counterbore portion 124. When measuring the current flowing through the primary side wiring 24 by the current transformer, either the magnet 14A or the section 16A is fitted in the counterbore portion 124.

  FIG. 6 is a schematic view illustrating the configuration of the current transformer in a state where the primary side wiring is passed through the wiring hole. In FIG. 6, the magnet 14A is fitted into the counterbore portion 124. By fitting the magnet 14A into the counterbore portion 124, a bias magnetic field is generated inside the core portion 12A.

  According to the above configuration, by generating a bias magnetic field using magnet 14A, for example, the magnetic field strength H inside core portion 12A can be positioned near point C in FIG. 14 in a default state. it can. Then, if the current to be measured flows in this state, for example, the linear region from point C to point B in FIG. 14 can be efficiently used, and therefore the IT product can be increased.

  Further, by preparing a plurality of magnets 14A having different magnetic forces, the strength of the bias magnetic field formed inside the core portion 12A can be adjusted.

  FIG. 7 is a conceptual view illustrating the state of the bias magnetic field formed inside the core when the magnet is fitted into the counterbore. In FIG. 7, the magnetic flux 26A and the magnetic flux 26B which show a bias magnetic field are illustrated. FIG. 8 is an enlarged view illustrating the bias magnetic field illustrated in FIG.

  The magnetic flux 26A in FIG. 7 and FIG. 8 is a part of the magnetic flux formed by the magnet 14A and is formed in the counterclockwise direction inside the core 12A, and the pole on the opposite side around the core 12A. to go into. On the other hand, the magnetic flux 26B in FIG. 7 and FIG. 8 is another part of the magnetic flux formed by the magnet 14A and enters the opposite pole without going around the core portion 12A.

  Since the bias magnetic fields as illustrated in FIGS. 7 and 8 are generated, the bias magnetic field of the current transformer according to the present embodiment is weaker than the bias magnetic field of the current transformer in the first embodiment. Therefore, this weak bias magnetic field can be used to fine-tune the strength of the magnetic field.

Third Embodiment
The current transformer according to the present embodiment will be described. In the following description, constituent elements similar to the constituent elements described in the embodiments described above are illustrated with the same reference numerals, and the detailed description thereof is appropriately omitted.

<About the configuration of the current transformer>
FIG. 9 is a schematic diagram illustrating a configuration for realizing a current transformer according to the present embodiment. As illustrated in FIG. 9, the current transformer includes a core portion 12C, a secondary side wire 18 at least partially wound around the core portion 12C, and output terminals 20 at both ends of the secondary side wire 18; A shunt resistor 22 connected across the output terminals 20, a magnet 14C, and a section 16C made of the same material as that of the core portion 12C are provided.

  The core portion 12C includes a gap portion 120C that divides the core portion 12C in the circumferential direction of the primary side wiring, and a remaining portion 126C that is a portion that is not the gap portion 120C.

  The magnet 14C and the section 16C both have the same dimensions as the gap 120C, and are fitted into the gap 120C. When measuring the current flowing to the primary side wiring by the current transformer, the magnet 14C or the segment 16C is fitted in the gap portion 120C.

  Here, a recess 121C is formed at the end of the remaining portion 126C that faces (that is, is adjacent to) the gap 120C. Further, the magnet 14C fitted into the gap portion 120C has a convex portion 140C fitted into the concave portion 121C of the end of the remaining portion 126C. Similarly, the section 16C fitted into the gap 120C has a projection 160C fitted into the recess 121C at the end of the remaining part 126C. The convex portion 140C and the convex portion 160C illustrated in FIG. 9 have a thick tip.

  The convex portion 140C is formed on the magnet 14C, and the convex portion 160C is formed on the segment 16C. Therefore, the magnet 14C and the segment 16C fitted in the gap portion 120C are compared to the case where the convex portion is not formed. It becomes difficult to remove from 120C. In particular, since the thickness of the tip of the convex portion is formed thick, the magnet 14C and the segment 16C fitted in the gap portion 120C are less likely to be detached from the gap portion 120C.

  When the current to be measured flows while the magnet 14C is fitted in the gap 120C, the direction of the magnetic flux formed by the magnet 14C and the direction of the magnetic flux formed by the core 12C by the measured current are opposite to each other. The core portion 12C and the magnet 14C repel each other, and the magnet 14C may come out of the gap portion 120C. By having the configuration exemplified in the present embodiment, the magnet 14C can be securely attached to the core portion 12C, so that the magnet 14C can be made difficult to be detached.

Fourth Embodiment
The current transformer according to the present embodiment will be described. In the following description, constituent elements similar to the constituent elements described in the embodiments described above are illustrated with the same reference numerals, and the detailed description thereof is appropriately omitted.

<About the configuration of the current transformer>
FIG. 10 is a schematic view illustrating a configuration for realizing a current transformer according to the present embodiment. As illustrated in FIG. 10, the current transformer includes a core portion 12D, a secondary side wire 18 at least partially wound around the core portion 12D, and output terminals 20 at both ends of the secondary side wire 18; A shunt resistor 22 connected across the output terminals 20, a magnet 14D, and a section 16D made of the same material as that of the core portion 12D are provided.

  The core portion 12D includes a counterbore portion 124D and a remaining portion 126D which is a portion other than the counterbore portion 124D.

  The magnet 14D and the segment 16D both have the same dimensions as the counterbore portion 124D, and are fitted into the counterbore portion 124D. When measuring the current flowing through the primary side wiring 24 by the current transformer, the magnet 14D or the segment 16D is fitted in the counterbore portion 124D.

  Here, in the counterbore portion 124D, a thread groove is formed on the inner peripheral surface. On the other hand, screw threads corresponding to the screw grooves are respectively formed on the outer peripheral surfaces of the magnet 14D and the section 16D.

  When the current to be measured flows while the magnet 14D is fitted in the counterbore 124D, the direction of the magnetic flux formed by the magnet 14D and the direction of the magnetic flux formed by the core 12D by the measured current are opposite to each other. There is a possibility that the magnet 14D may come off the counterbore portion 124D due to repulsion between the core portion 12D and the magnet 14D. By having the configuration exemplified in the present embodiment, the magnet 14D can be reliably fitted in the counterbore portion 124D, so the magnet 14D can be made difficult to be detached.

Fifth Embodiment
The current transformer according to the present embodiment will be described. In the following description, constituent elements similar to the constituent elements described in the embodiments described above are illustrated with the same reference numerals, and the detailed description thereof is appropriately omitted.

<About the configuration of the current transformer>
FIG. 11 is a schematic diagram illustrating a configuration for realizing a current transformer according to the present embodiment. As illustrated in FIG. 11, the current transformer includes a core portion 12E having a plurality of countersunk portions 124E, a secondary wiring 18 at least partially wound around the core 12E, and both ends of the secondary wiring 18. An output terminal 20, a shunt resistor 22 connected across two output terminals 20, a magnet 14, a plurality of magnets 14A, a section 16 made of the same material as the core 12E, and the same material as the core 12E And a plurality of sections 16A.

  The core portion 12E includes a gap portion 120E which divides the core portion 12E in the circumferential direction of the primary side wiring, and a remaining portion 126E which is a portion other than the gap portion 120E.

  The magnet 14 and the segment 16 both have the same dimensions as the gap 120E, and are fitted into the gap 120E. When measuring the current flowing to the primary side wiring 24 by the current transformer, the magnet 14 or the piece 16 is fitted in the gap portion 120E.

  On the other hand, the plurality of magnets 14A and the plurality of segments 16A both have the same dimensions as the corresponding counterbore portions 124E, and are fitted into the respective counterbore portions 124E. When measuring the current flowing through the primary side wiring 24 by the current transformer, the magnet 14A corresponding to each counterbore portion 124E or the corresponding segment 16A is fitted. Note that it is not necessary to fit either the magnet 14A or the segment 16A into all the counterbore portions 124E. For example, the magnet 14A is fitted into the two counterbore portions 124E, and the segment 16A is fitted into one counterbore portion 124E. It may be

  In the bias magnetic field generated by the magnet 14 fitted in the gap portion 120E, the magnetic flux is formed in the counterclockwise direction inside the core portion 12E as in the case illustrated in FIG. Get into the opposite pole.

  On the other hand, in the bias magnetic field generated by the magnet 14A fitted in the counterbore portion 124E, a part of the magnetic flux goes around the core portion 12E and enters the opposite pole as in the case illustrated in FIGS. 7 and 8. However, the other part enters the opposite pole without going around the core part 12E. Therefore, the bias magnetic field generated by the magnet 14A fitted in the counterbore portion 124E becomes a magnetic field weaker than the bias magnetic field generated by the magnet 14 fitted in the gap portion 120E.

  By utilizing the difference in the strength of the generated bias magnetic field as described above, for example, the magnet 14 fitted in the gap portion 120E is the main magnet, and the magnet 14A fitted in the counterbore portion 124E is the adjustment magnet Thus, it is possible to adjust the bias magnetic field with high accuracy.

  In addition, it is also possible to change the magnet 14 in this Embodiment into a shape like the magnet 14C in FIG. Moreover, it is also possible to change the magnet 14A in this Embodiment into a shape like the magnet 14D in FIG.

  Further, it is also possible to change the section 16 in the present embodiment to a shape like the section 16C in FIG. Moreover, it is also possible to change the section 16A in the present embodiment into a shape like the section 16D in FIG.

Sixth Embodiment
The current transformer according to the present embodiment will be described. In the following description, constituent elements similar to the constituent elements described in the embodiments described above are illustrated with the same reference numerals, and the detailed description thereof is appropriately omitted.

<About the configuration of the current transformer>
In the second embodiment, the magnet 14A fitted in the counterbore portion 124 is allowed to freely rotate in the counterbore portion 124. Similarly, in the fourth embodiment, the magnet 14D fitted in the counterbore portion 124D is allowed to freely rotate in the counterbore portion 124D. Similarly, in the fifth embodiment, the magnet 14A fitted in the counterbore portion 124E is allowed to freely rotate in the counterbore portion 124E. In this case, the rotation axis of the magnet 14A is not particularly limited. For example, in FIGS. 6 and 11, it is possible to assume a rotation axis in a direction intersecting with the extending direction of the core portion, such as a rotation axis perpendicular to the paper it can.

  FIG. 12 is a conceptual view illustrating the state of the bias magnetic field formed inside the core when the magnet 14A is fitted into the counterbore 124. As shown in FIG. In FIG. 12, the line connecting the north pole and the south pole of the magnet 14A is along the diameter direction of the core portion 12A.

  The magnetic flux 26C in FIG. 12 does not go around the core 12A and enters the opposite pole. Therefore, in such a case, no bias magnetic field is generated in the core portion 12A.

  On the other hand, when the line connecting the N pole and the S pole of the magnet 14A is orthogonal to the diameter direction of the core portion 12A, the magnetic flux 26A goes around the core portion 12A as illustrated in FIGS. 7 and 8. To produce the maximum bias magnetic field.

  Thus, it is possible to adjust the strength of the bias magnetic field by adjusting the direction of the magnetic pole of the magnet 14A.

<About the effect produced by the embodiment described above>
Next, the effects produced by the embodiments described above are illustrated. In the following description, although the effect is described based on the specific configuration exemplified in the embodiment described above, it is exemplified in the present specification as long as the same effect occurs. Other specific configurations may be substituted.

  Also, the replacement may be performed across multiple embodiments. That is, the respective configurations illustrated in different embodiments may be combined to produce the same effect.

  According to the embodiment described above, the current transformer includes the core portion 12, the secondary side wire 18, the shunt resistor 22, the at least one magnet 14, and the section 16. The core portion 12 is disposed to surround the primary side wiring 24 along at least a part of the circumferential direction of the primary side wiring 24. Also, the core 12 is made of a soft magnetic material. The secondary side wiring 18 is wound around at least a part of the core portion 12. The shunt resistor 22 is connected across both ends of the secondary wire 18. The magnet 14 is attachable to the core 12 and generates a magnetic field inside the core 12. The section 16 is attachable to the core 12 and is made of the same material as the core 12. The core portion 12 includes a defect portion which is a portion where the material of the soft magnetic material is not provided, and a remaining portion 126 which is a portion which is not a defect portion. Here, the defect portion corresponds to, for example, the gap portion 120. The segment 16 and the magnet 14 are fitted in the gap portion 120 in an exchangeable manner.

  According to such a configuration, it is possible to generate a bias magnetic field as needed by the magnet 14 exchangeably fitted in the defect portion without using an external power supply or the like. In addition, by fitting the segment 16 into the defect portion, it can be used as a normal current transformer which does not generate a bias magnetic field. Therefore, for example, when the current to be measured flows only in one direction, the measurement is performed in a state where the magnet 14 is fitted in the defect portion, and when the current to be measured flows bidirectionally, the defect portion The measurement can be performed in a state where the section 16 is fitted in the defect portion so that the magnetic flux does not leak from the Further, by preparing a plurality of sections 16 having different magnetic properties, the sections 16 to be fitted into the defect portion can be changed according to the magnetic properties of the core portion 12. Moreover, since the magnet 14 is removable from the defect | deletion part, according to the direction through which a to-be-measured electric current flows, it is also possible to change direction to insert the magnet 14 into.

  In addition, about another structure illustrated by this-application specification other than these structures, it can be abbreviate | omitted suitably. That is, if at least these configurations are provided, the effects described above can be produced.

  However, when at least one of the other configurations exemplified in the present specification is appropriately added to the configuration described above, that is, it is exemplified in the present specification which is not mentioned as the configuration described above. The same effect can be produced even if the other configurations are added as appropriate.

  Further, according to the embodiment described above, the current transformer includes the plurality of magnets 14 having different magnetic forces. Then, at least one of the section 16 and the plurality of magnets 14 is replaceably fitted in the gap portion 120. According to such a configuration, the strength of the bias magnetic field generated inside the core portion 12 can be adjusted by making the magnetic force of the magnet 14 fitted into the gap portion 120 different.

  Further, according to the embodiment described above, the defect portion is the gap portion 120 which divides the core portion 12 in the circumferential direction of the primary side wiring 24. Then, the section 16 and the magnet 14 are fitted in the gap portion 120 in an exchangeable manner. According to such a configuration, the bias magnetic field can be generated as needed by the magnet 14 which is fitted exchangeably in the gap portion 120 without using an external power supply or the like.

  Further, according to the embodiment described above, the recess 121C is formed at the end of the remaining part 126C facing the gap part 120C. The section 16C has a convex portion 160C corresponding to the concave portion 121C. Further, the magnet 14C has a convex portion 140C corresponding to the concave portion 121C. According to such a configuration, the section 16C or the magnet 14C is securely fixed in a state of being fitted into the gap portion 120C. Therefore, the repulsion between the magnetic flux formed by the magnet 14C and the magnetic flux formed by the core 12C due to the measured current occurs when the measured current flows while the magnet 14C is fitted in the gap 120C. The force can suppress the magnet 14C from coming out of the gap portion 120C.

  Moreover, according to the embodiment described above, the defect part is a concave-shaped counterbore part 124 formed in the core part 12A. Then, the section 16A and the magnet 14A are exchangeably fitted in the counterbore portion 124. According to such a configuration, the generated bias magnetic field is weaker than when the magnet 14 is fitted into the gap 120. Therefore, for example, in the core portion having both the gap portion 120E and the counterbore portion 124E as in the core portion 12E, the counterbore portion 124E is caused to generate a main bias magnetic field by the magnet 14 fitted into the gap portion 120E. By generating a weak bias magnetic field by the fitted magnet 14A, the strength of the generated bias magnetic field can be adjusted with high accuracy.

  Moreover, according to the embodiment described above, a thread groove is formed on the inner peripheral surface of the counterbore portion 124D. Further, the section 16D and the magnet 14D each have a thread corresponding to a thread groove. According to such a configuration, the section 16D or the magnet 14D is reliably fixed in a state of being fitted into the counterbore portion 124D. Therefore, the repulsion between the magnetic flux formed by the magnet 14D and the magnetic flux formed by the core 12D due to the measured current occurs when the measured current flows with the magnet 14D fitted in the counterbore 124D. It can suppress that magnet 14D separates from counterbore part 124D by force.

  Further, according to the embodiment described above, the magnet 14A is rotatable in the counterbore portion 124 or in the counterbore portion 124E. In addition, the magnet 14D is rotatable in the counterbore portion 124D. According to such a configuration, the magnet is produced by orienting the pole direction of the magnet (that is, the line connecting the north pole and the south pole of the magnet) in a direction along or crossing the diameter direction of the core portion. The strength of the bias magnetic field can be adjusted.

  Further, according to the embodiment described above, the magnet 14A is rotatable in the counterbore portion 124 or in the counterbore portion 124E with a direction intersecting the extending direction of the core portion 12A as a rotation axis. In addition, the magnet 14D is rotatable with a direction intersecting with the extending direction of the core portion 12D in the counterbore portion 124D as a rotation axis. According to such a configuration, the strength of the bias magnetic field generated by the magnet can be adjusted by orienting the magnet poles in the direction along or across the diameter direction of the core portion.

Regarding Modifications of the Embodiments Described Above
In the embodiment described above, although the material, material, material, size, shape, relative arrangement relationship or condition of implementation of each component may also be described, these are exemplifications in all aspects. Thus, the present invention is not limited to the ones described in the present specification.

  Accordingly, numerous modifications and equivalents not illustrated are contemplated within the scope of the technology disclosed herein. For example, when modifying at least one component, adding or omitting it, and further extracting at least one component in at least one embodiment and combining it with a component of another embodiment Shall be included.

  Further, unless there is a contradiction, “one or more” may be included as a component described as “one” in the embodiments described above.

  Furthermore, each component in the embodiments described above is a conceptual unit, and within the scope of the technology disclosed in the present specification, one component is composed of a plurality of structures. , A case where one component corresponds to a part of a structure, and a case where a plurality of components are provided in one structure.

  Further, each component in the embodiment described above includes a structure having another structure or shape as long as the same function is exhibited.

  In addition, the description in the present specification is referred to for all purposes related to the present technology, and none is recognized as prior art.

  Further, in the embodiment described above, when a material name or the like is described without being specified, unless the contradiction arises, the material includes other additives, for example, an alloy or the like. Shall be included.

  12, 12A, 12C, 12D, 12E, 12F core portions 14, 14, 14A, 14C, 14D magnets, 16, 16A, 16C, 16D sections, 18 secondary side wiring, 20 output terminals, 22 shunt resistance, 24 primary side wiring 26, 26A, 26B, 26C Magnetic flux, 28 current directions, 30 cables, 32 input terminals, 34 power supplies, 36 limiting resistances, 120, 120C, 120E gaps, 121C recesses, 122 wiring holes, 124, 124D, 124E countersunk , 126, 126A, 126C, 126D, 126E remaining portions, 140C, 160C convex portions.

Claims (8)

A core portion made of a soft magnetic material and disposed so as to surround the primary side wire along at least a part of the circumferential direction of the primary side wire;
A secondary side wire wound around at least a part of the core portion;
A shunt resistor connected across both ends of the secondary side wiring;
At least one magnet attachable to the core and generating a magnetic field inside the core;
A section attachable to the core and made of the same material as the core;
The core portion is
A defective portion which is a portion where the material of the soft magnetic body is not provided;
And a remaining part that is not the defect part,
In the defect portion, the section and the magnet are fitted exchangeably.
Current transformer. The current transformer includes a plurality of the magnets having different magnetic forces,
At least one of the section and the plurality of magnets is replaceably fitted to the defect;
The current transformer according to claim 1. The defective portion is a gap portion which divides the core portion in the circumferential direction of the primary side wiring,
The section and the magnet are interchangeably fitted in the gap.
The current transformer according to claim 1 or claim 2. A recessed portion is formed at an end of the remaining portion facing the gap portion,
The section and the magnet each have a convex portion corresponding to the concave portion.
The current transformer according to claim 3. The deficient portion is a concave-shaped counterbore portion formed in the core portion,
The section and the magnet are interchangeably fitted in the counterbore portion,
The current transformer according to any one of claims 1 to 4. A screw groove is formed on the inner peripheral surface of the counterbore portion,
The section and the magnet each have a thread corresponding to the thread groove,
The current transformer according to claim 5. The magnet is rotatable in the counterbore portion.
A current transformer according to claim 5 or 6. The magnet is rotatable in a counterbore portion with a direction intersecting a direction in which the core portion extends as a rotation axis.
A current transformer according to claim 5 or 6.

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