JPH10106871A - Current transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save manhour by fastening coils with an insulating band, although troublesome adjusting work has been necessary in a manufacturing process, in order to maintain adequate insulation interval between a primary coil and a secondary coil. SOLUTION: After a primary coil 1 is wound, a coil bundle is fastened at a plurality of portions, by using a band 6 composed of insulating material having a specific thickness. While the interval between the primary coil 1 and the secondary coil 2 is ensured by the thickness of the band 6, the primary coil 1 is coaxially arranged outside the secondary coil 2, and unified in a body by molding using insulating resin 9. A core 4 is so arranged that it penetrates the center of both coils and covers the peripheral parts of both coils. Thereby it is made easy to maintain the form of the primary coil 1 after winding, and it is made unnecessary to adjust the interval between both coils at the time of assembling to the secondary coil 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a current transformer in which a coil portion is insulated by a resin material.

[0002]

Heretofore, there has been known a so-called molded type current transformer in which a primary coil and a secondary coil having different diameters are arranged coaxially, and the coils and their surroundings are insulated by a resin material. is there. FIG. 4 shows a cross-sectional structure of one example. The size (cross-sectional area) of the illustrated primary coil 1 is determined by the rated current value and the overcurrent. However, since a rectangular copper wire or a strip is used, the shape and cross-sectional area of the coil are usually used. In some cases, the finished shape cannot be maintained due to springback after winding around the coil. Therefore, wrapping insulation tapes,
The shape was retained by a method such as impregnation with resin and curing.

When the primary coil 1 and the secondary coil 2 are integrally molded with an insulating material, a cotton tape or the like is wrapped in a semi-wrapped shape over the entire peripheral surface to secure an insulating distance between the two coils. The shape and dimensions were maintained by impregnating and curing the resin. However, at this time, if an attempt is made to maintain an appropriate insulation distance between the two coils, it is necessary to adjust the amount of winding of the insulating paper 5 around the outer peripheral surface of the secondary coil 2, which requires a lot of man-hours. In addition, the above-described springback may be more difficult to maintain the shape and dimensions only by wrapping a cotton tape or the like, and the primary coil may expand in the axial and radial directions, and the overall size of the current transformer may be reduced. Sometimes became larger. Furthermore, work such as masking of the terminal connection portion of the electric wire was also very difficult.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has a primary coil disposed coaxially outside a secondary coil and holding the primary coil at a predetermined insulation distance therebetween. In the current transformer, the periphery is molded with an insulating resin and integrated, and the core is arranged to penetrate the center of both coils and cover the periphery of both coils. After the winding, the coil bundle is bound at a plurality of places with a band made of an insulating material having a predetermined thickness, and an interval between the primary coil and the secondary coil is secured by the thickness of the band. This facilitates the maintenance of the shape of the primary coil after winding, and eliminates the need for adjusting the distance between the two coils even when the secondary coil is incorporated into the secondary coil, thereby saving labor.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an appearance of a primary coil constituting a current transformer according to an embodiment of the present invention, and FIG. 2 is a right side view of FIG. In both figures, a primary coil 1 uses a copper flat wire and a core jig (not shown) and a wire end 1.
After a is pulled out and fixed, it is formed by winding it into a multilayer cylindrical shape while adjusting the shape appropriately, and fixing the terminal end 1b of the electric wire in the cylindrical tangential direction. Next, the formed coil bundle is bound by a band 6 made of resin or the like having a predetermined thickness and insulation and heat resistance at four locations in the circumferential direction of the primary coil 1 formed in a cylindrical shape.

[0006] Of the binding locations, two locations are at the beginning and end of winding of the coil, and the remaining two locations are at intermediate positions therebetween. In addition, the size of the joining portion of the band 6 is increased to about twice the thickness of the band. However, if the joining portion is located on the outer peripheral surface or the side surface of the primary coil 1, there is no particular problem in the coil configuration. Further, in this embodiment, a resin tying band with irreversible slip-off is adopted as the tying means, so that the tying can be performed easily and sufficient tightening strength can be obtained. The cylindrical primary coil 1
In contrast, if the band tie points are provided at three equally distributed positions, the purpose of tying can be achieved for the time being, but it is difficult to maintain the shape due to the large coil size or small wire diameter. May increase the number of binding portions of the band as appropriate.

Next, the tip 1a and the end 1b of the wire are
The primary terminals 7 and 8 are connected, an insulating paper 5 (see FIG. 3) is slightly wound around the outer peripheral surface of the secondary coil 2 (not shown), and the primary coil 1 is placed so that the inner peripheral surface of the band 6 contacts the outer peripheral surface. And the primary coil 1 and the secondary coil 2 are integrated.
Next, the primary coil 1 and the secondary coil 2 while maintaining the integration are inserted into a mold (not shown), and an insulating material 9 such as an epoxy resin is injected. 2
Fill around and cure and remove. Next, the iron core 4 and a frame (not shown) are assembled to complete the current transformer shown in FIG.

This embodiment can be easily formed by winding the primary coil 1 and then binding the coil bundle with the band 6. In addition, in the process of incorporating the primary coil 1 and the secondary coil 2, the man-hours for securing the distance between the two, fixing, positioning, and the like are reduced. Further, in the cylindrical gap formed between the primary coil 1 and the secondary coil 2, the band 6 itself also has a duct function, and as a result, a resin or the like is provided between the primary coil 1 and the secondary coil 2. Is reliably filled, and a current transformer with a small size and good insulation performance can be manufactured.

Although the above-described embodiment is applied to a coil having a perfect circular cross section, the present invention can be similarly applied to a coil having another shape such as an oval cross section. In addition, this embodiment has been carried out with respect to a molded current transformer using a resin material as an insulating material, but if the coil is appropriately fixed with a binding band using the primary terminal and the inner peripheral surface of the secondary coil together, The present invention is also applicable to the case where the coil is held in another insulating medium such as gas or pure rim oil.

[0010]

As described above, according to the present invention, after the primary coil is wound, the coil bundle is bound at a plurality of places with a band made of an insulating material having a predetermined thickness to form the primary coil and the secondary coil. The spacing is ensured by the thickness of the band. This makes it easy to maintain the shape of the primary coil after winding, and also eliminates the need for adjusting the distance between the two coils when assembling the secondary coil, thereby saving labor in the manufacturing process.

[Brief description of the drawings]

FIG. 1 is an external view of a primary coil constituting a current transformer according to an embodiment of the present invention.

FIG. 2 is a right side view of FIG.

FIG. 3 is a sectional view of a current transformer according to the embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Primary coil 1a Wire tip 1b Wire termination 2 Secondary coil 4 Iron core 5 Insulation paper 6 Band 7,8 Primary terminal 9 Insulation material

Claims (1)

[Claims] 1. A primary coil is coaxially arranged outside a secondary coil, and a periphery of the primary coil is molded integrally with an insulating resin in a state where the two coils are held at a predetermined insulation distance. In a current transformer formed by arranging an iron core so as to penetrate the center of the coil and cover the periphery of both coils, after winding the primary coil, the coil bundle is banded at a plurality of locations and made of an insulating material having a predetermined thickness. Wherein the gap between the primary coil and the secondary coil is secured by the thickness of the band.