JP2020170832A - Current transformer and zero-phase-sequence current transformer - Google Patents

Abstract

To provide a current transformer and zero-phase-sequence current transformer, capable of supporting winding and a core without being stressed when pressure-molding a coil inserted into an outer case, preventing degradation in electrical characteristics and improving assemblability of a lead wire and charging properties and adhesive properties of molding resin.SOLUTION: A current transformer includes a guiding shape 5 which can increase a contact area with molding resin 9 by fitting a rib 2 for coil support onto both or either of an inner cylinder 3 and an outer cylinder 4 of an outer case 1 to increase a width thereof so that a contact area with a coil increases and by easily guiding a lead wire 10 and the molding resin 9 into a lead wire insertion part 15 to a bottom part thereof.SELECTED DRAWING: Figure 2

Description

The present invention relates to a current transformer and a zero-phase current transformer for measuring an alternating current or an alternating current on which direct current is superimposed, for example, a half-wave sinusoidal alternating current or a leakage current thereof.

FIG. 1 is a schematic view showing a conventional general current transformer. In the conventional current transformer, the secondary winding W2 is wound around a closed magnetic path made of an annular magnetic core, and the primary winding W1 through which the current to be measured flows penetrates the central opening of the closed magnetic path. In that operation, when the current I1 flows through the primary winding W1, a preferably proportional current I2 corresponding to the magnitude of the current I1 is generated in the secondary winding W2 by electromagnetic induction. At this time, by connecting a bearing resistor to the secondary winding W2, a voltage signal is output to the secondary winding W2, and as a result, the current I1 flowing through the primary winding W1 can be measured as a voltage signal. Become.

In addition, as a conventional method for manufacturing a current transformer, a metal mold is prepared, a core having at least one winding, that is, a coil is inserted into the mold in a state of being incorporated in an outer case, and the mold is closed. There is a method of pressure molding and integrally sealing molding by filling a mold with a heat-fluidized molding resin under pressure. (See, for example, Patent Document 1)

JP-A-7-183145 Fig. 1, Fig. 3

In a conventional current transformer, when a coil is incorporated in an outer case and sealed by pressure molding, a portion where the coil approaches the side wall of the outer case occurs due to the pressure during molding. In that case, since the molding resin is difficult to fill in the portion where the coil and the outer case are close to each other, the molding resin is likely to be peeled off in the vicinity thereof, and the withstand voltage characteristic is also deteriorated. In addition, the position of the core shifts due to the movement of the coil due to the molding pressure, so that the equilibrium characteristics deteriorate when used as a zero-phase current transformer.

Further, the hole diameter of the cylindrical lead wire insertion portion of the outer case of the conventional current transformer is about the wire diameter of the lead wire because it also serves as the positioning of the lead wire, and the viscosity of the molding resin is adjusted during pressure molding. It cannot be filled unless it is lowered. Further, the contact area between the molding resin around the lead wire and the outer case is small, and a large pull-out strength cannot be obtained.

In addition, when the coil is positioned using the bobbin of a conventional current transformer and sealed by pressure molding, the ribs provided on the bobbin for positioning have a structure in which the contact area with the coil is small. In addition, when the coil is pressed against the rib by the pressure during molding, a large stress is locally applied to the winding, causing coating breakage and disconnection. In addition, the winding part of the coil is easily deformed, and it is deformed by being pressed against the positioning rib by the forming pressure, so that the core position shifts accordingly, and the equilibrium characteristic deteriorates when used as a zero-phase current transformer. To do.
Further, on the outer peripheral portion of the coil, the positioning rib is provided only in the vicinity of the hard copper wire for the lead wire, and the positioning of the coil is insufficient in other places.
Further, when pressed against the positioning rib by the forming pressure, a force is also applied to the core inside the coil, the characteristics of the core are changed, and the electrical characteristics are deteriorated.

In addition, since the hard copper wire for the lead wire of the conventional current transformer is integrally molded with the bobbin, the lead wire having lower strength and heat resistance temperature than the outer case is used as the lead wire like a lead wire having a coating. It cannot be used.

The current transformer or zero-phase current transformer in the present invention is a coil in which an annular magnetic core having a high relative permeability characteristic is wound, and a lead wire having a coating as a lead wire is attached to the end of the winding. It has a structure in which a molding resin that is housed in an outer case and heated and fluidized is poured and integrally pressure-molded and sealed. The outer case has an outer cylindrical shape and an inner cylindrical shape, and both or one of them has an outer case. It has ribs that support the coil, and the ribs have a continuous length with a central angle of 60 ° or more from the center of the coil, and are provided at at least one place.

As described above, in the present invention, the ribs that support the coil have a continuous length of 60 ° or more from the center of the coil, and are provided at least in one or more places. Since the coil can be supported while minimizing the stress on the coil winding and the core in the coil caused by contact, electricity generated by disconnection, coating breakage and deformation of the winding part, coil misalignment, and force applied to the core. It is possible to prevent deterioration of the target characteristics.

It is a schematic diagram which shows a general current transformer. It is a figure which shows the outer case structure used for the current transformer or the zero-phase current transformer in Embodiment 1 of this invention. It is a figure which shows the outer case structure used for the current transformer or the zero-phase current transformer in Embodiment 2 of this invention. It is a figure which shows the outer case structure used for the current transformer or the zero-phase current transformer in Embodiment 3 of this invention. It is a figure which shows the current transformer or the zero-phase current transformer in Embodiments 1-3 of this invention.

の関係を持ち、リブ２の高さはコイル１４の高さＬ７の０．５〜０．８倍程度である。外側円筒４側には、コイル中心からの中心角は６０°以上（例えば９０°）の長さのリブ２が２カ所あり、内側円筒３には、コイル中心からの中心角は６０°以上（例えば９０°）の長さのリブ２が２カ所ある。
図２（ｃ）（ｄ）において１５はリード線挿入部、８はコイル１４の巻線を引き出すための隙間を有する巻線引出し部、５は巻線に接続したリード線１０を収納する誘い込み形状、７はケース１から外部にリード線１０を引き出すリード線引き出し部である。
このように構成された変流器もしくは零相変流器１００においては、リブ２の高さをコイル１４の高さＬ７の０．５〜０．８倍にすることで、リブ２上部に成形樹脂が充填される余地を設けつつ、コイル１４を支持することができる。
また、リブ２長さをコイル１４中心からの中心角は６０°以上となるようにすることでコイル１４との接触面積が大きくなり、加圧成形時の圧力により押し付けられた場合においても巻線に断線や被覆破れを生じさせるようなストレスを与えず、さらにコアに対しても電気的特性が変化するような力が加わらないようにすることができる。
また、図２（ｅ）にあるようにリード線挿入部１５はリード線１０先端を、外ケース１底部まで導き、さらにリード線１０を反らせて成形樹脂９との接着性を高めることが可能なテーパ形状５ａを有する誘い込み形状５により、リード線１０の組付け性を向上させるとともに成形樹脂９の充填性および外ケース１との接着性も向上させることができる。
なお、リブ２は図２（ｆ）のように内側円筒３のみに設けたり、図２（ｇ）のように外側円筒４のみに設けても、コイルを支持することは可能であるため、内側円筒３及び外側円筒４の両方に設けた場合と同等の効果が得られる。Embodiment 1.
5A and 5B are a current transformer or a zero-phase current transformer 100 according to the first embodiment of the present invention, FIG. 5A is a plan view, FIG. 5B is a sectional view taken along line AA, and FIG. Is a front view. FIG. 5D is an isometric view of the coil 14.
In FIG. 5D, 13 is a winding wound around the core portion 11, 10 is a lead wire for a lead wire having a coating, and 14 is a coil in which they are combined. The outer diameter of the coil 14 is L5, the inner diameter is L6, and the height is L7.
In FIG. 5A, the coil 14 is incorporated in the outer case 1, the molding resin 9 which has been heated and fluidized is poured, and the molding resin 9 is integrally pressure-molded and sealed.
2A and 2B are an outer case 1 used for the current transformer or the zero-phase current transformer 100 according to the first embodiment of the present invention, FIG. 2A is a plan view of the outer case 1, and FIG. 2B is AA. FIG. 2 (c) is an isometric view, FIG. 2 (d) is a sectional view taken along line BB, and FIG. 2 (e) is a diagram showing a lead wire 10 in the lead-in shape 5.
In FIGS. 2A and 2B, the outer case 1 has an inner cylinder 3 and an outer cylinder 4, and each cylinder is provided with a rib 2 for coil positioning. Assuming that the thickness dimension of the rib 2 is L1 on the outer cylinder 4 side and L2 on the inner cylinder 3 side, the inner diameter dimension of the outer cylinder 4 is L3, and the outer diameter of the inner cylinder 3 is L4.

The height of the rib 2 is about 0.5 to 0.8 times the height L7 of the coil 14. On the outer cylinder 4 side, there are two ribs 2 having a central angle of 60 ° or more (for example, 90 °) from the coil center, and on the inner cylinder 3, the central angle from the coil center is 60 ° or more (for example, 90 °). For example, there are two ribs 2 having a length of 90 °).
In FIGS. 2C and 2D, 15 is a lead wire insertion portion, 8 is a winding lead-out portion having a gap for pulling out the winding of the coil 14, and 5 is an invitation shape for accommodating the lead wire 10 connected to the winding. , 7 are lead wire lead-out portions for pulling out the lead wire 10 from the case 1.
In the current transformer or zero-phase current transformer 100 configured in this way, the height of the rib 2 is 0.5 to 0.8 times the height L7 of the coil 14 to form the upper part of the rib 2. The coil 14 can be supported while providing room for the resin to be filled.
Further, by setting the rib 2 length so that the central angle from the center of the coil 14 is 60 ° or more, the contact area with the coil 14 becomes large, and the winding is wound even when pressed by the pressure during pressure molding. It is possible to prevent the core from being subjected to stress that causes disconnection or coating breakage, and to prevent the core from being subjected to a force that changes its electrical characteristics.
Further, as shown in FIG. 2E, the lead wire insertion portion 15 can guide the tip of the lead wire 10 to the bottom of the outer case 1 and further warp the lead wire 10 to improve the adhesiveness with the molding resin 9. The invitation shape 5 having the tapered shape 5a can improve the assembling property of the lead wire 10 and also improve the filling property of the molding resin 9 and the adhesiveness to the outer case 1.
Since the coil can be supported even if the rib 2 is provided only on the inner cylinder 3 as shown in FIG. 2 (f) or only on the outer cylinder 4 as shown in FIG. 2 (g), it is inside. The same effect as when provided on both the cylinder 3 and the outer cylinder 4 can be obtained.

Embodiment 2.
In the present embodiment, a part different from the first embodiment will be described. FIG. 3 is an outer case 1 of the current transformer or zero-phase current transformer 100 according to the second embodiment of the present invention, FIG. 3A is a plan view, and FIG. 3B is a sectional view taken along line AA. 3 (c) is an isometric view, and FIG. 3 (d) is a sectional view taken along line BB. FIG. 3E is a diagram showing a lead wire 10 in the invitation shape 16.
In FIGS. 3C and 3D, 15 is a lead wire insertion portion, 8 is a winding lead-out portion having a gap for pulling out the winding of the coil 14, and 16 is an invitation shape for accommodating the lead wire 10 connected to the winding. , 6 is a cylindrical lead wire positioning portion, and 7 is a lead wire lead-out portion for pulling out the lead wire 10 from the case 1.
In the current transformer or zero-phase current transformer 100 configured in this way, as shown in FIG. 3 (e), the lead wire insertion portion 15 has a lead wire 10 at the tip of the lead wire 10 due to a lead wire 16 having a tapered shape 16a. It can be guided to the positioning portion 6 to improve the assembling property of the lead wire 10, and also improve the filling property of the molding resin 9 and the adhesiveness with the outer case 1.

Embodiment 3.
In the present embodiment, a part different from the first embodiment will be described. FIG. 4 is an outer case 1 of the current transformer or zero-phase current transformer 100 according to the third embodiment of the present invention, FIG. 4 (a) is a plan view, and FIG. 4 (b) is a sectional view taken along line AA. 4 (c) is an isometric view, and FIG. 4 (d) is a sectional view taken along line BB. FIG. 4 (e) is a diagram showing a lead wire 10 in the invitation shape 12.
In FIGS. 4C and 4D, 15 is a lead wire insertion portion, 8 is a winding lead-out portion having a gap for pulling out the winding of the coil 14, and 12 is an invitation shape for accommodating the lead wire 10 connected to the winding. , 12a is a step-shaped lead wire positioning portion, 6 is a cylindrical lead wire positioning portion, and 7 is a lead wire lead-out portion for drawing out the lead wire 10 from the case 1.
In the current transformer or zero-phase current transformer 100 configured in this way, as shown in FIG. 4 (e), the lead wire insertion portion 15 has a lead wire 10 tip due to a lead wire insertion shape 12 having a stepped shape 12a. Can be guided to the lead wire positioning unit 6 to improve the assembling property of the lead wire and the filling property of the molding resin 9. By making the invitation shape 12 a stepped shape 12a, the adhesiveness between the molding resin 9 and the outer case 1 can be further improved.

1 Outer case 2 Ribs to prevent misalignment 3 Outer case inner cylinder 4 Outer case outer cylinder 5 Invitation shape (lead wire inlet to outer case bottom)
5a Tapered shape 6 Lead wire positioning part 7 Lead wire lead-out part 8 Winding lead-out part 9 Molding resin 10 Lead wire 11 Core part 12 Invitation shape (stepped, lead wire insertion part inlet to lead wire positioning cylinder 6 inlet)
12a Step shape 13 Winding 14 Coil 15 Lead wire insertion part 16 Invitation shape (lead wire insertion part inlet to lead wire positioning cylinder 6 inlet)
16a Tapered shape 100 current transformer and zero-phase current transformer

Claims (6)

A coil in which a ring is wound around an annular magnetic core with high relative permeability characteristics. A lead wire with a coating as a lead wire is attached to the end of the winding, and a molded resin that has been heated and fluidized is poured into the outer case and integrated. It has a structure that is pressure-molded and sealed.
The outer case has an outer cylindrical shape and an inner cylindrical shape, and both or one of them has a rib that supports the coil, and the rib has a central angle of 60 ° or more from the center of the coil. A current transformer or zero-phase current transformer characterized by having a continuous length and being in at least one place. The current transformer or zero-phase current transformer according to claim 1, wherein the rib has a height of 0.5 to 0.8 times the height of the coil. In the rib, the rib on the outer cylinder side has a thickness of half the difference between the inner diameter of the outer cylinder and the outer diameter of the coil, and the rib on the inner cylinder side has the inner diameter of the coil and the outer diameter of the inner cylinder. The current transformer or zero-phase current transformer according to claim 1 or 2, wherein the current transformer has a thickness of half of the difference between the two. The outer case has a lead wire insertion portion for accommodating the lead wire, and the lead wire insertion portion includes a wall portion surrounding the lead wire with a predetermined space, a gap portion through which the winding is passed, and a gap portion through which the winding is passed. The current transformer or zero-phase current transformer according to any one of claims 1 to 3, wherein the current transformer has a tapered shape that narrows toward the bottom surface of the outer case. The outer case has a lead wire insertion portion for accommodating the lead wire, and the lead wire insertion portion includes a wall portion surrounding the lead wire with a predetermined space, a gap portion through which the winding is passed, and a gap portion through which the winding is passed. The current transformer or zero-phase current transformer according to any one of claims 1 to 3, further comprising a positioning portion for positioning the lead wire and a tapered shape narrowing toward the lead wire positioning portion. .. The outer case has a lead wire insertion portion for accommodating the lead wire, and the lead wire insertion portion includes a wall portion surrounding the lead wire with a predetermined space, a gap portion through which the winding is passed, and a gap portion through which the winding is passed. The current transformer or zero-phase current transformer according to any one of claims 1 to 3, wherein the positioning portion for positioning the lead wire and the top surface of the lead wire positioning portion have a stepped shape. ..

Images