Design and manufacturing method of inner shield of pot-type insulator

Abstract

The present invention relates to the technical field of medium and high voltage switchgear, and discloses a design of inner shielding of a pot-type insulator, including an insulating pot body, wherein a central insert is embedded in the middle of the inner side of the insulating pot body, and a shielding ring is embedded in the inner side of the insulating pot body, wherein the shielding ring is composed of a plurality of arc-shaped shielding segments, and also discloses a method for manufacturing inner shielding of a pot-type insulator, including the following steps: S1, casting in a vacuum state by automatic pressure gel method; S2, sandblasting and cleaning the casting; S3, spraying conductive material on the surface of the high temperature resistant insulating casting body. The solid insulating material of the present invention is cast and formed by automatic pressure gel method in a vacuum state, which can ensure that there is no internal stress in the production and manufacturing process of the product, and the shielding ring adopts a segmented design, and there is no problem of shrinkage thermal stress, so that the voltage distribution inside and along the surface of the pot-type insulator can be adjusted, and the field strength of the three intersections of the ground potential flange can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of medium and high voltage switchgear, and in particular to a design of an inner shield of a pot-type insulator and a manufacturing method thereof. Background Art

[0002] As a key component of GIS and GIL equipment, the basin insulator plays the role of isolating the gas chamber, supporting the conductor and insulating. At present, due to the design and manufacturing process of the basin insulator, there will be a certain gas gap between the epoxy resin body and the outer metal flange. The gas gap is an air gap. With the increase of voltage level, the gap is prone to partial discharge. Therefore, products with higher voltage levels will be equipped with shielding rings inside the basin insulator. With the development of high voltage and ultra-high voltage and the demand for miniaturization of products, the surface field strength of the basin insulator is getting higher and higher under the condition that the overall structure and creepage distance remain unchanged. In particular, the three-point problem of ground potential and high voltage area is very prominent. It is easy to have gap discharge and surface flashover during the experiment, affecting the performance and life of the product. At present, the industry generally adopts the design of ground potential shielding rings to reduce the field strength at the fillet position of the busbar flange and the surface field strength of the insulating parts.

[0003] A Chinese patent discloses a basin-type insulator (authorization announcement number CN102842394B). This patent improves the electric field distribution along the surface of the insulator to prevent flashover. However, the shielding ring used is formed by metal processing. Due to the large difference in thermal expansion coefficients between the metal and the insulating casting, internal stress is easily generated inside the product after casting. There will be a gap on the joint surface of the shielding ring and the insulating casting, which affects the local discharge of the product and the reliability of long-term use.

[0004] A Chinese patent discloses a metal flange basin insulator with embedded sensors (authorization announcement number CN203479962U). The patent embeds the sensor in the metal flange basin insulator to make the device integrated and easy to process. The local discharge signal can be obtained stably and reliably, and it can also be used as a sensor for a live display device, overcoming the problem of embedding by opening a hand hole in the prior art. However, the sensor has the hidden danger of easy leakage and high cost. In addition, since the signal sensor used is a metal spring, the spring is easily deformed during the production process, resulting in uneven surface field strength on both sides of the basin insulator, resulting in surface flashover. In addition, the end of the shielding spring is not an arc transition, so the internal area of ​​the end will also have casting internal stress, and the electric field will be more concentrated. Summary of the invention

[0005] The object of the present invention is to provide a design of an inner shield of a pot-type insulator and a manufacturing method thereof, so as to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A design of inner shielding of a basin-type insulator comprises an insulating basin body, a central insert is embedded in the middle of the inner side of the insulating basin body, and a shielding ring is embedded in the edge of the inner side of the insulating basin body, the shielding ring is composed of a plurality of arc-shaped shielding segments, and the plurality of arc-shaped shielding segments form a circular ring shape, both ends of the arc-shaped shielding segments are fixedly connected with ball heads, the arc-shaped shielding segments comprise a high-temperature resistant insulating casting body, the outer surface of the high-temperature resistant insulating casting body is sprayed with a conductive coating layer, and the outer arc side of the high-temperature resistant insulating casting body is embedded with a plurality of supporting feet, and the inner side of the supporting feet is embedded with mounting inserts.

[0008] As a further solution of the present invention: the cross-section of the high temperature resistant insulating cast body is elliptical, and the inner and outer sides of the elliptical cross-section adopt arc structures with different curvatures, and the curvature of the inner side of the elliptical cross-section of the high temperature resistant insulating cast body is greater than the curvature of the outer side.

[0009] As a further solution of the present invention: the conductive coating layer can be made of zinc spraying, spraying conductive paint or graphene material.

[0010] A method for manufacturing an inner shield of a pot-type insulator comprises the following steps:

[0011] S1. Fix the mounting insert to the casting mold, and then pour the casting material into the mold by automatic pressure gelation under vacuum;

[0012] S2. After the castable material is cooled and solidified, the cast part is taken out and locked on the spraying tooling by installing the insert. The cast part is sandblasted and polished by using a sandblasting device to roughen its surface. After cleaning, a high temperature resistant insulating cast body is obtained.

[0013] S3. Use spraying equipment to spray conductive material on the surface of the high-temperature resistant insulating cast body to form a conductive coating layer, remove the installation insert from the support foot to obtain the arc-shaped shielding segment, and then assemble several arc-shaped shielding segments into a shielding ring. The same casting process is used to cast the insulating basin body and the center insert.

[0014] As a further solution of the present invention: the casting material in step S1 can be made of a solid insulating material having a thermal expansion coefficient close to that of epoxy resin, and preferably a high temperature resistant epoxy resin having a thermal transition temperature ≥ 120°C. The casting material in step S1 can also be made of nylon material.

[0015] As a further solution of the present invention: the mold in the S1 step is preheated for 3 to 4 hours before pouring, so that the mold temperature is stabilized at 80 to 85°C, and then the casting material is poured. The vacuum degree of the casting material during pouring is controlled at 100 to 120 Pa, and the vacuum degree of the casting material during cooling and solidification molding is controlled at 300 to 400 Pa.

[0016] As a further solution of the present invention: the high temperature resistant epoxy resin is prepared by mixing A epoxy resin, alumina powder, dimethyl phthalate and phthalic anhydride curing agent in a ratio of 20:5:1:1.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention adopts a solid insulating material with a thermal expansion coefficient similar to that of epoxy resin or high-temperature resistant epoxy resin, and casts it in an automatic pressure gel method under a vacuum state, and then sprays a conductive material on its surface, so as to achieve a shielding effect, and can ensure that there is no internal stress in the product production process. At the same time, in order to improve the casting process of the basin insulator, the shielding ring adopts a segmented design, and there is no problem of shrinkage thermal stress, so that the voltage distribution inside and along the surface of the basin insulator can be adjusted, and the field strength of the three intersections of the ground potential flange can be reduced. Ball heads are provided at both ends of the arc-shaped shielding segment, which can change the internal and surface electric field distribution of the insulating basin body, reduce the problem of field strength concentration at the end, and improve the withstand voltage level of the product. At the same time, the support feet can be adjusted according to the design, the fixing method is flexible, and the installation space is large. The inner and outer sides of the cross section of the high-temperature resistant insulating casting body adopt arc structures with different curvatures, and the curvature of the inner side is greater than that of the outer side. The use of a larger arc on the inner side can reduce the field strength distribution at the high-voltage end, and can also reduce the surface field strength of the insulating basin body. The use of a smaller arc on the outer side can strengthen the support and improve its strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of a design of inner shielding of a pot-type insulator;

[0020] Figure 2 It is a schematic diagram of the structure of a shielding ring in a design of an inner shield of a pot-type insulator and a manufacturing method thereof;

[0021] Figure 3 This is a partial cross-sectional schematic diagram of the arc-shaped shielding section in the design of the inner shield of a basin-type insulator and its manufacturing method.

[0022] In the figure: 1. insulating basin; 2. center insert; 3. shielding ring; 31. arc-shaped shielding segment; 311. high temperature resistant insulating casting body; 312. conductive coating layer; 313. mounting insert; 314. support foot; 32. ball head. DETAILED DESCRIPTION

[0023] See also Figures 1 to 3 In an embodiment of the present invention, a design of inner shielding of a basin-type insulator includes an insulating basin body 1, a central insert 2 is embedded in the middle of the inner side of the insulating basin body 1, and a shielding ring 3 is embedded in the edge of the inner side of the insulating basin body 1. The shielding ring 3 is composed of a plurality of arc-shaped shielding segments 31, and the plurality of arc-shaped shielding segments 31 form a circular ring shape. The shielding ring 3 adopts a segmented design, which can effectively adjust the distribution of voltage inside and along the surface of the basin-type insulator, and reduce the field strength of the three intersection points of the ground potential flange. Both ends of the arc-shaped shielding segment 31 are fixedly connected with a ball head 32, and the internal and surface electric fields of the insulating basin body 1 can be changed through the ball head 32. Distribution, reducing the problem of field strength concentration at the end, and improving the voltage resistance level of the product. The arc-shaped shielding segment 31 includes a high-temperature resistant insulating casting 311. The outer surface of the high-temperature resistant insulating casting 311 is sprayed with a conductive coating layer 312, and the outer arc side of the high-temperature resistant insulating casting 311 is embedded with a plurality of supporting feet 314. The supporting feet 314 can be adjusted according to the design, the fixing method is flexible, and the installation space is large. The inner side of the supporting feet 314 is embedded with an installation insert 313. The installation insert 313 can be used to fix the arc-shaped shielding segment 31 after the arc-shaped shielding segment 31 is cast, and then it is convenient to grind and spray it.

[0024] Preferably, the cross-section of the high-temperature resistant insulating cast body 311 is elliptical, and the inner and outer sides of the elliptical cross-section adopt arc structures with different curvatures. The curvature of the inner side of the elliptical cross-section of the high-temperature resistant insulating cast body 311 is greater than that of the outer side. A larger arc is used on the inner side to reduce the field strength distribution at the high-voltage end, and can also reduce the surface field strength of the insulating basin 1. A smaller arc is used on the outer side to strengthen support.

[0025] Preferably, the conductive coating layer 312 can be made of zinc spraying, conductive paint spraying or graphene material, so that it has higher stability and good conductivity.

[0026] A method for manufacturing an inner shield of a pot-type insulator comprises the following steps:

[0027] S1, fixing the mounting insert 313 to the casting mold, and then pouring the casting material into the mold by automatic pressure gelation under vacuum;

[0028] S2, after the castable material is cooled and solidified, the cast part is taken out and locked on the spraying tooling by installing the insert 313, and the cast part is sandblasted and polished by using a sandblasting device to roughen its surface, and after cleaning, a high temperature resistant insulating cast body 311 is obtained;

[0029] S3. Use a spraying device to spray conductive material on the surface of the high-temperature resistant insulating casting body 311 to form a conductive coating layer 312. Remove the installation insert 313 from the support foot 314 to obtain the arc-shaped shielding segment 31. Then assemble several arc-shaped shielding segments 31 into a shielding ring 3. Use the same casting process to cast the insulating basin body 1 and the center insert 2.

[0030] Preferably, the casting material in step S1 can be made of a solid insulating material having a thermal expansion coefficient close to that of epoxy resin, and preferably a high-temperature resistant epoxy resin having a thermal transition temperature ≥ 120°C is used, so that it has the characteristics of not being easily deformed at high temperatures and has good stability. The casting material in step S1 can also be made of nylon material, which can improve its production efficiency.

[0031] Preferably, the mold in step S1 is preheated for 3 to 4 hours before pouring, so that the mold temperature is stabilized at 80 to 85°C, and then the casting material is poured. The vacuum degree of the casting material during pouring is controlled at 100 to 120Pa, and the vacuum degree of the casting material during cooling and solidification is controlled at 300 to 400Pa, thereby preventing bubbles from appearing inside the casting and improving the strength of the casting.

[0032] Preferably, the high temperature resistant epoxy resin is prepared by mixing A epoxy resin, alumina powder, dimethyl phthalate, and phthalic anhydride curing agent in a ratio of 20:5:1:1, thereby improving the quality and production efficiency of the high temperature resistant insulating casting 311.

[0033] In order to better illustrate the technical effect of the present invention, the following experiments are used to illustrate:

[0034] The inner shield of the pot-type insulator made by the method of the present invention is taken as an example, and the inner shield of the pot-type insulator made by conventional design and metal processing or metal spring processing is taken as a comparative example; the creeping field strength (unit: kV / mm) of the inner surface of the shielding ring and the insulating pot body is respectively detected, and the results are shown in the following Table 1:

[0035] Table 1. Experimental field strength results of embodiments and comparative examples

[0036]

[0037] From the analysis of Table 1, it can be concluded that the field strength on the inner surface of the shielding ring and the field strength along the surface of the insulating basin in the embodiment are both smaller than the field strength on the inner surface of the shielding ring and the field strength along the surface of the insulating basin in the comparative example. Therefore, it can be concluded that the embodiment significantly changes the internal and surface electric field distribution of the insulating basin, reduces the problem of field strength concentration at the end, and thereby improves the voltage resistance level of the product.

[0038] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A pot-type insulator, comprising an insulating pot body (1), characterized in that: A central insert (2) is embedded in the middle of the inner side of the insulating basin (1), and a shielding ring (3) is embedded in the edge of the inner side of the insulating basin (1). The shielding ring (3) is composed of a plurality of arc-shaped shielding segments (31), and the plurality of arc-shaped shielding segments (31) form a circular ring shape. Both ends of the arc-shaped shielding segments (31) are fixedly connected with ball heads (32). The arc-shaped shielding segments (31) include a high-temperature resistant insulating casting (311). The outer surface of the high-temperature resistant insulating casting (311) is sprayed with a conductive coating layer (312), and the outer arc side of the high-temperature resistant insulating casting (311) is embedded with a plurality of supporting feet (314), and the inner side of the supporting feet (314) is embedded with a mounting insert (313).

2. A pot-type insulator according to claim 1, characterized in that: The cross section of the high temperature resistant insulating casting (311) is elliptical, and the inner and outer sides of the elliptical cross section adopt arc structures with different curvatures, and the curvature of the inner side of the elliptical cross section of the high temperature resistant insulating casting (311) is greater than the curvature of the outer side.

3. A pot-type insulator according to claim 1, characterized in that: The conductive coating layer (312) is made of zinc spraying, conductive paint spraying or graphene material.

4. A method for manufacturing a pot-type insulator according to claim 1, characterized in that: The following steps are involved: S1. Fix the installation insert (313) on the casting mold, and then use the automatic pressure gel method to cast the casting material into the mold under vacuum; S2. After the casting material is cooled and solidified, take out the casting part, and lock the casting part on the spraying tooling through the installation insert (313), use sandblasting equipment to sandblast and polish the casting part to roughen its surface, and obtain a high-temperature resistant insulating casting body (311) after cleaning; S3. Use a spraying device to spray a conductive material on the surface of the high-temperature resistant insulating casting body (311) to form a conductive coating layer (312), remove the installation insert (313) from the support foot (314), and obtain an arc-shaped shielding segment (31), and then assemble several arc-shaped shielding segments (31) into a shielding ring (3), and use the same casting process to cast the insulating basin (1) and the center insert (2).

5. A method for manufacturing a pot-type insulator according to claim 4, characterized in that: The casting material in step S1 is made of a solid insulating material having a thermal expansion coefficient close to that of epoxy resin.

6. A method for manufacturing a pot-type insulator according to claim 5, characterized in that: The casting material is a high temperature resistant epoxy resin with a thermal transition temperature of ≥120°C.

7. A method for manufacturing a pot-type insulator according to claim 5, characterized in that: The casting material is made of nylon.

8. The method for manufacturing a pot-type insulator according to claim 4, characterized in that: The mold in step S1 is preheated for 3 to 4 hours before pouring, so that the mold temperature is stabilized at 80 to 85°C, and then the casting material is poured. The vacuum degree of the casting material during pouring is controlled at 100 to 120 Pa, and the vacuum degree of the casting material during cooling and solidification is controlled at 300 to 400 Pa.

9. The method for manufacturing a pot-type insulator according to claim 6, characterized in that: The high temperature resistant epoxy resin is prepared by mixing A epoxy resin, aluminum oxide powder, dimethyl phthalate and phthalic anhydride curing agent in a ratio of 20:5:1:1.

Images