JPH08153640A - Insulator molding method and die of split current transformer - Google Patents

Abstract

PURPOSE: To coat the outermost layer of a split CT with insulator uniform in thickness without deforming a split core. CONSTITUTION: A coil 5 is wound on a split core 3 through the intermediary of an insulating tube 4 before an insulator 7 is molded. A molding core material 22 of the same shape with the split core 3 is prepared. The molding core material 22 is inserted into the insulating tube 4 in place of the split core 3 and then set inside a molding die 20, and then insulating material is cast into the molding die for molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding an insulator such as a split type current transformer and a molding die.

[0002]

2. Description of the Related Art Generally, in a measuring transformer used as various sensors in a transmission line facility, an annular core provided near a high-voltage conductor is divided in the circumferential direction in advance and assembled together for use. There is a so-called split type. As a typical example of a split transformer,
Current transformers for overhead power lines or overhead ground lines (hereinafter "CT")
Is called).

FIG. 5 is a view showing a standard split CT in the related art. This divided type CT1 is attached to the outer peripheral side of the high voltage conductor A such as an overhead power transmission line by integrally combining two divided bodies 2 and 2 which are previously divided into two in the circumferential direction.

FIG. 6 is a view showing a cross section of the split type CT1. A semicircular split core 3 that forms a closed magnetic circuit that surrounds the high-voltage conductor A in order from the center side, an insulating tube 4 that covers the split core 3, and a coil that is wound on the insulating tube 4 (secondary winding Line 5 to convert the current flowing through the conductor A into a small current that can be easily measured and then take out the current information. The coil 5 is covered (molded) with an insulator 7 made of epoxy resin, rubber or the like in order to maintain insulation against the high voltage conductor A.

Conventionally, when the insulator 7 is formed on the outermost layer of the split type CT1, molding by a mold is generally performed.

FIG. 7 is a view showing an example of a mold used for such molding. The molding die 10 is composed of a main die 11 divided into arcs and end dies 14 and 14 attached to the main die 11, and a coil is formed in an arc-shaped cavity 15 partitioned by these. The body 6 is installed. As shown in FIG. 8, the coil body 6 is obtained by drawing the split core 3 into the insulating tube 4 and then winding the coil 5 on the insulating tube 4.
Is formed by winding.

As shown in FIG. 7, after the coil body 6 is set in the cavity 15 in the molding die 10 along the center line, a raw material (epoxy resin, rubber or the like) is injected, and after the raw material is cured, the metal is The mold 10 is released and the molded product is taken out. As a result, the insulator 7 is formed on the outer circumference of the coil body 6, and the half-divided body 2 as shown in FIG. 5 is obtained.

[0008]

However, the above-mentioned conventional insulator molding method and molding die 10 have the following problems.

When the coil body 6 is set in the molding die 10, both ends of the coil body 6 must be fixed to the end dies 14, 14. Therefore, in the conventional method, as shown in an enlarged view in FIG. 7, the drop hole 14 is formed on the upper surface of the end mold 14.
A was formed, and the end of the split core 3 was inserted and set in this. However, both ends of the split core 3 are dropped into the hole 1
There is a problem in that the coil body 6 cannot be accurately positioned in the center of the cavity 15 only by inserting the coil body 4a and 14a, and uneven thickness occurs in the insulator 7.

In order to eliminate the uneven thickness of the insulator 7, the central portion of the coil body 6 may be held by the pressing portion 16 (FIG. 7). However, if the middle of the coil body 6 is gripped, the insulator 7 must be repaired after the mold 10 is released (after the pressing portion 16 is removed), which is extremely complicated.

If, for example, a permalloy core is used as the split core 3, the material itself is mechanically weak, so that the split core 3 is deformed without being able to withstand the pressure in the die 10, and the characteristics of the split CT. There is a problem of changing. In fact, when a rubber mold is applied around the coil body 6, the rubber pressure inside the mold during vulcanization is approximately 120 kg / cm ²
It was confirmed that the permalloy core 3 could not withstand this pressure and was deformed.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a split type structure in which an insulating material can be coated around a coil body with a uniform thickness and easily and without deforming the split core. An object of the present invention is to provide a method for molding an insulator such as a current transformer and a molding die.

[0013]

In order to achieve the above object, the present invention provides a coil wound around an outer circumference of a split core obtained by splitting an annular core in a circumferential direction through an insulating tube, and the split core and the insulating tube. And a method for forming an insulator such as a split type current transformer that forms an insulator on the outer circumference of a coil, a molding core having the same shape as the split core is made in advance, and the molding core is used as the split core. It is replaced and inserted into an insulating tube, which is then set in a mold and injected with an insulating material for molding.

Here, when the molding core is set in the mold, it is preferable that both ends of the molding core are tightly fixed.

Further, the insulator molding die of the present invention comprises a main mold having a cavity for accommodating the split core, the insulating tube and the coil, and the main mold is closed at both end openings of the cavity. An end die to be mounted, a molding core having the same shape as the split core provided in the insulating tube in place of the split core, and both ends of the molding core are tightly fixed to the end die. And a fixing means.

Here, the fixing means comprises a screw hole formed on both end surfaces of the molding core material, and a bolt screwed into the screw hole through a through hole from the outside of the end die. Is preferred.

[0017]

According to the present invention, since the split core in the insulating tube is replaced with the molding core material and set in the mold, both ends of the molding core material can be closely supported by the mold. . That is, if a molding core material is used instead of the split core,
Fixing means can be provided between the molding core material and the mold, and the molding core material can be accurately positioned and set in the mold by simply fixing the two ends of the molding core material to the mold. .
Therefore, the insulator can be molded only by supporting both ends of the molding core material without gripping the central portion of the coil as in the conventional case.

Further, by using the molding core material instead of the split core, various materials can be selected as the molding core material. Therefore, if the molding core material is made of a material having high strength and hardness, even if the insulator is rubber, it is possible to prevent the molding core material from being deformed due to the pressure inside the mold during vulcanization. .

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 20 denotes a mold used in the method of the present invention. As in the conventional case, a main mold 11 composed of an upper mold 13 and a lower mold 12 divided into arcs, and a main mold. 1
It is composed of end molds 14, 14 attached to the lower surface of 1. Main mold 11 inside, ie upper mold 13 and lower mold 1
A cavity 15 having a substantially rectangular cross section and bent in a semi-circular arc shape is defined between the two, and both end openings of the cavity 15 are closed by the end molds 14, 14.

Reference numeral 21 is a coil body set in the cavity 15 in the mold 20, and the insulator 7 is molded on the outer peripheral side of the coil body 21. As shown in an enlarged view in FIG. 1, the coil body 21 of the present embodiment is configured by winding a coil 5 around an outer periphery of a molding core material 22 with an insulating tube 4 interposed therebetween. 3 (FIG. 6) is a molding core material 22
The structure has been replaced with. As shown in FIG. 2, the molding core material 22 is formed to have substantially the same cross-sectional shape (rectangle) and size as the split core 3, but is made of a mechanically strong material so as not to be easily deformed. (Here, general steel S1OC) is used.

Both ends of the coil body 21 and the end die 1
As shown in FIG. 1, the fixing means 23 and 2 are provided between the fixing means 23 and 2.
3 is provided. The fixing means 23 is a molding core material 22.
For tightly fixing the end of the to the end mold 14,
A blind hole 24 formed in the end surface of the molding core 22
And the through hole 1 from the outside of the end mold 14 into the screw hole 24.
It is composed of a bolt 25 screwed through 4c so that the end surface of the molding core member 22 and the upper surface of the end die 14 can be brought into contact with each other and fixed.

Next, the method of molding the insulator having the above structure will be described in detail.

In manufacturing the split CT, the coil 5 is now mounted on the split core 3 via the insulating tube 4 as shown in FIG.
When the coil is wound, the split core 3 is pulled out from the insulating tube 4, and then the molding core material 22 prepared in advance is inserted to form the coil body 21.

Next, as shown in FIG. 1, the coil body 21 is set in the cavity 15 in the mold 20, and thereafter, an insulating material (epoxy resin or rubber material) is injected into the mold 20 for molding. To do.

Here, in setting the coil body 21 in the mold 20, first, both ends of the molding core material 22 are connected to the end mold 1.
4, 14 are inserted into the drop holes 14a, 14a on the upper surface, and in this state, the upper and lower molds 12, 13 and the end molds 14, 1
The mold 4 is clamped, and the coil body 21 is installed in the cavity 15 in the mold 20. Then, the molding core material 22
The end die 14, into the screw holes 24, 24 formed on both end faces of the
From the outside of 14, bolts 25, 25 are screwed together and tightened.

As a result, both ends of the molding core material 22 are drawn into the drop holes 14a, 14a, and the molding core material 2 is formed.
2 Both end surfaces are pressed against the upper surfaces of the end molds 14 and 14, and are set in the mold 20 in this state.

After the insulator is molded, the mold 20 is released and the molded product is taken out. Then, the molding core material 22 is extracted from the insulating tube 4 and replaced with the formal split core 3 to form the above-mentioned split. Form CT1 is constructed.

As described above, in this embodiment, the mold 2 is used.
Split core 3 in insulation tube 4 when molding insulator in 0
Is replaced with the molding core material 22 and the molding core material 22
Both end portions of the end mold 14 and 1 are fixed by fixing means 23 and 23.
The coil body 21 can be accurately aligned and set in the cavity 15 in the mold 20, and the uneven thickness of the insulator 7 can be eliminated to ensure uniform insulation. The body 7 can be molded. Particularly, in this embodiment, the screw holes 24, 2 formed on both end surfaces of the molding core material 22 are formed.
Since the bolts 25, 25 are screwed into the screw 4 and fixed to the end molds 14, 14, it is possible to prevent the coil body 21 from collapsing in the mold 20 as shown by phantom lines in FIG. Can be accurately installed along the center line of the cavity 15. Usually, if the end portion of the molding core material 22 is simply inserted into the drop hole 14a, a slight inclination of the coil body 21 causes a large displacement in the central portion (upper end portion) of the coil body 21.
In this respect, in the present embodiment, since the end face of the molding core material 22 is brought into contact with the end die 14, the molding core material 22 does not tilt and the center line of the cavity 15 is accurately aligned. Can be installed along.

Further, in the present embodiment, as described above, since the molding core 22 can be accurately set in the mold 20 by supporting the two ends of the core 22, it is necessary to grip the coil body 21 in the middle as in the conventional case. Disappears. Therefore, repair work after molding the insulator is not necessary, and the work can be simplified.

Further, according to this embodiment, the molding core material 22 is used.
Since it is formed of a material having high strength and high hardness, even when the insulator 7 is rubber, the molding core material 22 (and thus the coil 5) is not deformed by the pressure inside the mold during vulcanization. . Therefore, the characteristics of the split CT can be kept good.

In the above embodiment, as the fixing means 23 for holding the molding core material 22 on the end mold 14,
Although the screw hole 24 is formed in the end surface 22a of the molding core material 22 and the bolt 25 is screwed into the screw hole 24, it is natural that other structures may be used. Further, in the above embodiment, the molding core material 22 having the same shape as the split core 3 (that is, a semi-circular arc shape) is used, but as shown in FIG. You may.

[0033]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) It is possible to coat and form the insulator with a uniform thickness without uneven thickness.

(2) Repair work after molding is unnecessary, and the work can be simplified.

(3) The split core can be molded without being deformed by the pressure in the mold during rubber molding.

[Brief description of drawings]

FIG. 1 is a view for explaining a method of molding an insulator according to the present invention, showing a state in which a coil body covered with the insulator is set in a mold.

FIG. 2 is a perspective view showing a structural example of a molding core material used in the method of the present invention.

3 is a cross-sectional view taken along the line BB of FIG.

FIG. 4 is a perspective view showing another structural example of the molding core material used in the method of the present invention.

FIG. 5 is a diagram showing a conventional standard split CT.

6 is a partial cross-sectional view of the split CT shown in FIG. 7,
(a) shows a vertical section and (b) shows a horizontal section.

FIG. 7 is a diagram for explaining a conventional method of molding an insulator, showing a state in which a coil body covered with the insulator is set in a mold.

FIG. 8 is a perspective view showing a coil body covered with an insulator.

[Explanation of symbols]

 1 split type CT 2 split body 3 split core 4 insulating tube 5 coil 7 insulator 20 mold 21 coil body 22 molding core 23 fixing means

Front Page Continuation (72) Inventor Yoshihiro Kawanishi 2-56 Sudamachi, Mizuho-ku, Nagoya, Aichi Prefecture Insulator Nihon Higashi Co., Ltd. (72) Inventor Katsuo Moriya 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Hidaka Plant (72) Inventor Sumio Nomura 3-1-1 Sukegawa-cho, Hitachi-shi, Ibaraki Hitachi Rubber Processing Co., Ltd.

Claims (5)

[Claims] 1. A split current transformer in which a coil is wound around an outer circumference of a split core obtained by splitting an annular core in a circumferential direction through an insulating tube, and an insulator is formed on the split core, the insulating tube and the outer circumference of the coil. In the method of molding an insulator, etc., a molding core having the same shape as that of the split core is made in advance, the molding core is replaced with the split core, and the core is inserted into an insulating tube. A method for molding an insulator such as a split-type current transformer, which comprises setting it in a mold and injecting an insulating material for molding. 2. When the molding core is set in a mold, both ends of the molding core are tightly fixed.
A method for molding an insulator such as the split type current transformer described above. 3. The method for molding an insulator for a split current transformer or the like according to claim 1, wherein after molding the insulator, the molding core material is extracted from the insulating tube and replaced with a split core. 4. A split shape modification for winding a coil around an outer circumference of a split core obtained by splitting an annular core in a circumferential direction through an insulating tube, and molding an insulator around the split core, the insulating tube and the outer circumference of the coil. In an insulator molding die such as a flow vessel, a main mold having a cavity for accommodating the split core, the insulating tube and the coil, and an end portion attached to the main mold by closing both end openings of the cavity. A mold, a molding core having the same shape as the split core provided in the insulating tube in place of the split core, and a fixing means for tightly fixing both ends of the molding core to the end mold. A mold for forming an insulator such as a split-type current transformer, which is characterized by comprising: 5. The fixing means comprises a screw hole formed on both end surfaces of the molding core material, and a bolt screwed into the screw hole through a through hole from the outside of the end die. 4. A mold for molding an insulator such as the split type current transformer described in 4.