JP3520181B2 - Mold type current transformer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold type current transformer in which an iron core, a low voltage winding and a high voltage winding are molded with an insulating material such as resin and a metal base is attached to the low voltage winding side. Regarding vessels.

[0002]

In recent years, mold type current transformers have been miniaturized due to the high insulation of mold resin as an insulating material, good workability, and advances in manufacturing equipment and manufacturing technology. FIG. 7 shows a conventional structure of this type of molded current transformer. The mold type current transformer 1 has an iron core 2
The low-voltage winding 3 wound around the low-voltage winding 3, the high-voltage winding 4 wound around the low-voltage winding 3 and the cap nut 5 are molded by the molding resin 6. In this case, the high voltage terminal 4 a of the high voltage winding 4 is exposed to the outside from the upper surface of the molding resin 6, and the low voltage terminal 3 of the low voltage winding 3 is exposed.
The a is exposed to the outside from a recess 6a formed in the lower portion of the mold resin 6.

The mold type current transformer 1 is attached to a metal base 8 by screwing a screw 7 into a cap nut 5, and the base 8 is filled with sulfur hexafluoride gas by a bolt 9. The mold type current transformer 1 is attached to the closed switchboard, for example, on the floor surface 10 while being grounded.
Installed in a closed switchboard.

By the way, in a closed switchboard using sulfur hexafluoride gas as the insulating gas, since the creeping insulation distance can be secured by the high insulation performance of the sulfur hexafluoride gas, the air insulation type closed The creepage insulation distance from the high-voltage terminal 4a of the molded current transformer 1 to the base 8 can be reduced as compared with the case of being arranged in the switchboard.

Therefore, in the molded current transformer 1, it is not necessary to provide an uneven portion for obtaining a creeping insulation distance on the outer peripheral portion of the mold resin 6, and the shape can be simplified and further improved. Can be miniaturized. Due to the high insulation performance of the sulfur hexafluoride gas, it is possible to reduce the distance between the electric devices arranged in the closed switchboard and the distance between the molded current transformer 1 and other electric devices. As a result, the closed switchboard can be downsized and the installation area can be reduced.

However, with the above-mentioned structure, the high voltage terminal 4a of the mold type current transformer 1 and the external ground metal such as the metal case or the fitting of the other electric equipment adjacent to the mold type current transformer 1 are connected. Because the distance to the class becomes short,
Depending on the positional relationship between the high voltage winding 4 and the external ground metal,
It is considered that the electric field strength between them becomes high. Then, in such a state, when a high voltage is applied to the high-voltage winding 4 during a withstand voltage test or the like, an electric field is locally concentrated on the sharp portion of the external ground metal to cause partial discharge. This may cause a decrease in the discharge characteristic measurement value or a decrease in the external flashover voltage. In order to prevent such a situation from occurring, it is necessary to consider the layout size of the external ground metal.

The present invention has been made in view of the above circumstances, and an object thereof is to mold an iron core, a low-voltage winding and a high-voltage winding with an insulating material such as resin, and to form a metal on the low-voltage winding side. It is an object of the present invention to provide a mold type current transformer in which a partial discharge characteristic and an external flashover voltage can be improved without considering the arrangement dimension of external grounding metals in a base mounted type.

[0008]

According to the mold type current transformer of the present invention, an iron core and a low-voltage winding and a high-voltage winding wound around the iron core separately from each other are molded with an insulating material such as resin. In the case where a metal base is attached to the low-voltage winding side, there is a distance between the high-voltage winding and the base to maintain a predetermined insulation strength in the insulating material between the high-voltage winding and the base. And a conductive embedded member having a width dimension larger than that of the high-voltage winding and having a circular cross section,
It is characterized in that the embedded member is grounded (Claim 1).

According to the mold type current transformer having the above-mentioned structure, the insulating material between the high voltage winding and the base has a distance for maintaining a predetermined insulation strength from the high voltage winding, and the high voltage winding is present. A conductive embedded member having a circular cross section with a width dimension larger than that of the above is provided, and the embedded member is grounded, so that when a high voltage is applied to the high voltage winding during a withstand voltage test, etc. Even so, the electric field from the high voltage winding will be evenly distributed towards the buried member inside the insulation.

Therefore, unlike the conventional case, the electric field is not locally concentrated on the sharp portion of the external ground metal, the partial discharge characteristic and the external flashover voltage can be improved, and the external ground metal is arranged. There is no need to consider dimensions.

In this case, the outer peripheral portion of the embedded member may be knurled (claim 2). Further, in this case, a semiconductive winding member having good adhesion to the insulating material may be wound around the outer peripheral portion of the embedded member (claim 3). Also in this case,
The embedded member may be formed by winding a conductive wire material having a circular cross section into a spring shape (claim 4).

Further, in this case, the embedding member may be formed by winding a conductive mesh sheet in a cylindrical shape (claim 5). At this time, it is preferable that the winding end portion of the mesh sheet is on the side opposite to the high voltage winding (claim 6).

In the molded current transformer of the present invention, the iron core, the low-voltage winding and the high-voltage winding wound around the iron core so as to be spaced apart from each other are molded with an insulating material such as resin, and the low-voltage winding is molded. In a case where a metal base is attached to the wire side, the surface of the insulating material corresponding to the base extends in the width direction of the high-voltage winding and has a length larger than the width dimension of the high-voltage winding. A feature is that a groove having a size and having a circular cross section is formed, a semiconductive coating film is provided on a surface portion of the groove portion, and the coating film is grounded (claim 7).

According to the molded type current transformer having the above-mentioned structure, a length dimension that extends in the width direction of the high-voltage winding and is larger than the width dimension of the high-voltage winding on the surface portion of the insulating material corresponding to the base. Has a circular cross section, and a semi-conductive coating film is provided on the surface of the groove portion, and the coating film is grounded. Even when applied, the electric field from the high voltage winding will be evenly distributed towards the coating within the insulation. Therefore, it is possible to obtain the same effect as that of the first aspect.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of the present invention will be described below with reference to FIGS. The low-voltage winding 12 of the mold type current transformer 11 is wound around the outer periphery of an annular iron core 13, and the high-voltage winding 14 is linked to the low-voltage winding 12, that is, the straight portion 14a is the iron core. It is wound so as to penetrate through the central portion of 13. Also, the high voltage winding 1
Embedded members 15 and 15 made of a conductive material are disposed below the ends 14b and 14b of the straight line portion 14a in FIG.

Each of the embedding members 15 is at a distance that maintains a predetermined insulation strength with the high voltage winding 14, and as shown in FIG. 2, the upper ends of the inclined leg portions 15a, 15a are formed by a horizontal portion 15b. As connected, the front surface (the surface viewed from the arrow P direction in FIG. 1) is formed in a substantially “gate” shape, and its cross section is circular. At this time, the width W of the embedding member 15 is set to be larger than the width A of the high-voltage winding 14 and smaller than the width B of the base 16 described later. In addition, the outer peripheral portion of the embedded member 15 is knurled,
Both ends 15c, 15c are made of conductive cap nuts 17,
It is connected to 17 by silver brazing. The embedded members 15, 15 are symmetrically arranged as shown in FIG.

The low-voltage winding 12, the iron core 13,
High-voltage winding 14, buried members 15, 15 and cap nut 17
Is molded with a mold resin 18 as an insulating material to form the mold type current transformer 11. At this time, the mold resin 18 is molded into a shape having a recess 18a and an inclined surface 18b in the lower portion. In addition, the high voltage terminal 14c of the high voltage winding 14 is
8 is exposed to the outside from the upper surface portion of 8, and the low voltage terminal 12a of the low voltage winding 12 is exposed to the outside from the recess 18a.

Mold type current transformer 1 having the above-mentioned structure
1 is attached to the above-described base 16 made of a conductive material by screwing a screw 19 into a cap nut 17.
The base 16 is attached to and grounded, for example, on the floor surface 20 of a closed switchboard in which sulfur hexafluoride gas is filled as an insulating gas by bolts 16a as a mounting bracket made of a conductive material at four corners. Thus, when the molded current transformer 11 is attached to the closed switchboard via the base 16, the embedding member 15 is located between the high voltage winding 14 and the base 16, and the cap nut 17 and the base 16 are provided. Grounded through.

In addition to the mold type current transformer 11, a large number of electric devices are arranged in the closed switchboard, and the closed switchboard in which sulfur hexafluoride gas having high insulation performance is sealed. In the above, the distances between the electric devices and between the molded current transformer 11 and the other electric devices are set so as to be smaller than those in the case of an air-insulated closed switchboard, for example. As a result, the closed switchboard is downsized and the installation area is reduced.

In the first embodiment, an embedding member 15 made of a conductive material and having a width dimension W larger than the width dimension A of the high voltage winding 14 is molded in the molding resin 18 of the molding type current transformer 11 to form a molding type. When the current transformer 11 is attached to the closed switchboard, the embedding member 15 of the current transformer 11 has a high voltage winding 14 and a base 16
It was located between and and grounded. Therefore, even when a high voltage is applied to the high voltage winding 14 during a withstand voltage test or the like, the electric field from the high voltage winding 14 is
The resin is evenly distributed in the molding resin 18 toward the embedded member 15.

As a result, even if another electric device is arranged close to the molded type current transformer 11, unlike the conventional one, the electric field from the high voltage winding 14 is adjacent to the metal case of the electric device. It is possible to improve the partial discharge characteristics and the external flashover voltage by not concentrating locally on the sharp parts of the external grounding metal such as metal fittings and mounting brackets. There is no need. Further, in this case, since the outer peripheral portion of the embedding member 15 is knurled, the adhesion between the embedding member 15 and the mold resin 18 can be improved.

Next, the second embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Hereinafter, different parts will be described. In the second embodiment, instead of the embedding member 15 described in the first embodiment, an embedding member 21 having the same shape as the embedding member 15 and a circular cross section is provided, and the outer peripheral portion thereof is knurled. Instead, the semiconductor tape 22 (winding member in the present invention) having good adhesion to the mold resin 18 is wound. In this case, the embedded member 2
Like the burying member 15, 1 is a distance that maintains a predetermined insulation strength with the high-voltage winding 14, and the width dimension thereof is 1
It is set to be larger than the width dimension of 4 and smaller than the width dimension of the base 16, and both end portions 21a, 21a thereof are connected to the cap nuts 17, 17 by silver brazing.

According to the second embodiment, it is possible to obtain the same effects as the first embodiment. Particularly, in the second embodiment, the difference in linear expansion between the embedding member 21 and the mold resin 18 can be absorbed by the semiconductor tape 22 in the step of filling the mold resin 18.

Next, the third embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Hereinafter, different parts will be described. In the third embodiment, an embedding member 31 is provided instead of the embedding member 15 described in the first embodiment. The embedded member 31 is configured by winding a conductive wire 32 having a circular cross section in a spring shape (coil spring shape). Also in this case, the embedded member 31
Has the same shape as the burying member 15, and is similar to the burying member 15 at a distance that maintains a predetermined insulation strength with the high-voltage winding 14, and its width dimension is larger than the width dimension of the high-voltage winding 14,
Moreover, the width is set smaller than the width of the base 16, and both ends 31a, 31a thereof are connected to the cap nuts 17, 17 by silver brazing.

According to the third embodiment, it is possible to obtain the same effect as that of the first embodiment. Particularly, in the third embodiment, in the step of filling the mold resin 18, the mold resin 18 is filled in the spring-shaped gap portion of the wire rod 32, and the wire rod 32 is flexibly deformed due to the linear expansion of the mold resin 18. As a result, the adhesion between the embedding member 31 and the mold resin 18 can be improved.

Next, a fourth embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Hereinafter, different parts will be described. In the fourth embodiment, an embedding member 41 is provided instead of the embedding member 15 described in the first embodiment. The embedding member 41 is configured by winding a conductive mesh sheet 42 in a cylindrical shape, and a winding end portion 42a is wrapped around a winding start end portion. Also in this case, the embedded member 41
Has the same shape as the embedding member 15, and is similar to the embedding member 15 at a distance that maintains a predetermined insulation strength with the high-voltage winding 14, and its width dimension is larger than the width dimension of the high-voltage winding 14,
Further, it is set smaller than the width dimension of the base 16, and both ends 41a, 41a thereof are connected to the cap nuts 17, 17 by silver brazing. At this time, the winding terminal end portion 42a exposed on the surface is not on the high voltage winding 14 side but on the high voltage winding 1
It is on the side of the base 16 opposite to the side of 4.

According to the fourth embodiment, it is possible to obtain the same effect as that of the first embodiment. In particular, in the fourth embodiment, in the step of filling the mold resin 18, the mold resin 18 is filled in the interstices of the mesh of the mesh sheet 42, and the mesh sheet 42 is filled with the mold resin 1.
Since it is deformed flexibly with respect to the linear expansion of No. 8, the adhesiveness between the embedding member 41 and the mold resin 18 can be improved. In addition, the winding end portion 4 of the mesh sheet 42
Since 2a is on the side of the base 16 opposite to the high-voltage winding 14, it is possible to prevent the electric field from the high-voltage winding 14 from locally concentrating on the winding terminal end 42a.

Next, a fifth embodiment of the present invention will be described with reference to FIG.
Will be described with reference to. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Hereinafter, different parts will be described. The mold type current transformer 5 shown in the fifth embodiment.
In No. 1, the surface portion of the mold resin 18 corresponds to the base 16 and the portion corresponding to the ends 14b and 14b of the linear portion 14a in the high voltage winding 14 has a circular cross section and a length dimension. Larger than the width dimension of the high-voltage winding 14, and
Grooves 52, 52 smaller than the width dimension of the base 16 are formed. Then, the surface of the groove 52, 52 is coated with semi-conductive paint 53, 53 (coating according to the present invention). In this case, the semiconductive paints 53, 53 are electrically connected to the cap nuts 17, 17 by the conductive wires 54, 54 molded in the molding resin 18 and grounded.

In the fifth embodiment, the high-voltage winding is formed on the surface of the mold resin 18 at a portion corresponding to the base 16 and at the portions corresponding to the ends 14b and 14b of the straight portion 14a of the high-voltage winding 14. When the groove portions 52, 52 having a width dimension larger than the width dimension of 14 are formed, the surface portions of the groove portions 52, 52 are coated with the semiconductive paint 53, 53, and the mold type current transformer 51 is attached to the closed switchboard. In addition, the semiconductive paint 53, 53 is located between the high voltage winding 14 and the base 16 and is grounded. Therefore, even when a high voltage is applied to the high voltage winding 14 during a withstand voltage test or the like, an electric field from the high voltage winding 14 is generated by the molding resin 1
8 is evenly distributed toward the semi-conductive paint 53. As a result, it is possible to obtain the same effect as that of the first embodiment.

The present invention is not limited to the above embodiment, but can be modified or expanded as follows. In the fifth embodiment, instead of applying the semi-conductive paint 53 to the surface of the groove 52, a semi-conductive sheet or tape may be wound and stuck. In that case, the winding end of the sheet is The base 16 side is preferable. In the fifth embodiment, instead of molding the conductive wire 54 inside the molding resin 18, the base 16 is formed outside the molding resin 18.
You may connect directly to.

[0031]

As is apparent from the above description, according to the mold type current transformer of the first aspect, the insulating material between the high voltage winding and the base has a high insulation strength and a predetermined insulation strength. Since a conductive embedded member having a width dimension larger than that of the high-voltage winding and having a circular cross section is provided and the embedded member is grounded, Even when a high voltage is applied, the electric field from the high voltage winding is evenly distributed toward the embedded member inside the insulating material. As a result, the partial discharge characteristics and the external flashover voltage can be improved, and it is not necessary to consider the arrangement size of the external ground metal.

According to the mold type current transformer of the second aspect, since the outer peripheral portion of the embedded member is knurled,
It is possible to improve the adhesion between the embedded member and the insulating material.

According to the mold type current transformer of the third aspect, since the semi-conductive winding member having good adhesion to the insulating material is wound around the outer peripheral portion of the embedded member, in the step of filling the insulating material. The winding member can absorb the difference in linear expansion between the embedded member and the insulating material. According to the molded type current transformer of claim 4, since the embedded member is formed by winding a conductive wire rod having a circular cross section in a spring shape,
In the step of filling the insulating material, the insulating material is filled in the spring-shaped gaps in the wire material, and the wire material is flexibly deformed due to the linear expansion of the insulating material. It is possible to improve the property.

According to the mold type current transformer of the fifth aspect, since the embedding member is formed by winding the conductive mesh sheet in a cylindrical shape, the insulating material is meshed in the step of filling the insulating material. Filled in the gaps of the mesh in the sheet
In addition, the mesh sheet can be flexibly deformed by the linear expansion of the insulating material, and the adhesion between the embedding member and the insulating material can be improved.

According to the molded type current transformer of the sixth aspect, since the winding end portion of the mesh sheet is on the side opposite to the high voltage winding, the electric field from the high voltage winding is applied to the winding end portion. It is possible to prevent concentration locally.

According to the molded type current transformer of the seventh aspect, the length extending in the width direction of the high voltage winding and larger than the width dimension of the high voltage winding is provided on the surface portion of the insulating material corresponding to the base. When a high voltage is applied to the high voltage winding because a groove having a size and a circular cross section is formed, a semiconductive coating is provided on the surface of the groove, and the coating is grounded. Even so, the electric field from the high voltage winding will be evenly distributed towards the semi-conductive coating inside the insulation. This allows
Partial discharge characteristics and external flashover voltage can be improved,
It is not necessary to consider the layout size of the external ground metal.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a first embodiment of the present invention.

FIG. 2 is a front view (a) and a side view (b) of a buried member.

FIG. 3 is a view corresponding to FIG. 2 showing a second embodiment of the present invention.

FIG. 4 is a view corresponding to FIG. 2 showing a third embodiment of the present invention.

FIG. 5 is a view corresponding to FIG. 2 showing a fourth embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 1 showing a fifth embodiment of the present invention.

FIG. 7 is a view corresponding to FIG. 1 showing a conventional example.

[Explanation of symbols]

In the drawing, 11 is a mold type current transformer, 12 is a low voltage winding, 1
3 is an iron core, 14 is a high-voltage winding, 15 is an embedding member, 16 is a base, 18 is a molding resin (insulating material), 21 is an embedding member, 22 is a semiconductor tape (winding member), 31 is an embedding member, and 32 is an embedding member. Wire material, 41 is an embedding member, 42 is a mesh sheet, 42a is a winding terminal end, 51 is a mold type current transformer, 5
Reference numeral 2 is a groove portion, and 53 is a semiconductive coating material (coating film).

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Terumi Kato 2121 No. 21, Osamu, Asahi-cho, Mie-gun, Mie Prefecture Inside the Mie factory of Toshiba Corporation (56) References Fields investigated (Int.Cl. ⁷ , DB name) H01F 38/28

Claims (7)

(57) [Claims] 1. An iron core, a low-voltage winding and a high-voltage winding wound around the iron core separately from each other are molded with an insulating material such as resin, and a metal base is attached to the low-voltage winding side. In the molded current transformer, the insulating material between the high voltage winding and the base has a distance for maintaining a predetermined insulation strength with the high voltage winding, and the width dimension of the high voltage winding. A mold type current transformer, characterized in that a conductive embedding member having a larger width dimension and a circular cross section is provided, and the embedding member is grounded. 2. The mold type current transformer according to claim 1, wherein the embedded member has a knurled outer peripheral portion. 3. The mold type current transformer according to claim 1, wherein the embedded member has a semi-conductive winding member wound around the outer peripheral portion thereof and having good adhesion to the insulating material. 4. The molded current transformer according to claim 1, wherein the embedded member is formed by winding a conductive wire having a circular cross section in a spring shape. 5. The mold type current transformer according to claim 1, wherein the embedding member is formed by winding a conductive mesh sheet in a cylindrical shape. 6. The mold-type current transformer according to claim 5, wherein the winding end portion of the mesh sheet is on the side opposite to the high voltage winding side. 7. An iron core and a low-voltage winding and a high-voltage winding wound around the iron core separately from each other are molded with an insulating material such as resin, and a metal base is attached to the low-voltage winding side. In the molded current transformer, the surface portion of the insulating material corresponding to the base extends in the width direction of the high-voltage winding and has a length dimension larger than the width dimension of the high-voltage winding, and has a cross section. Forming a circular groove, a semi-conductive coating film is provided on the surface of the groove, and the coating film is grounded.