A method for improving the production qualification rate of dry casing

Abstract

The invention discloses a method for improving the production qualification rate of dry-type bushings, which belongs to the technical field of preparation of high-voltage bushings for power transmission and transformation. The method is as follows: in a glue-impregnated fiber capacitor dry-type bushing, the traditional arrangement of completely long pole plates in the axial direction is changed to an alternating arrangement of long pole plates that are completely penetrated in the axial direction and short pole plates that are not completely penetrated in the axial direction; long and short pole plates are arranged alternately in the direction of the outer circumferential axis of the dry-type bushing, and epoxy resin glue flows longitudinally and transversely between synthetic fiber woven meshes; finally, a glue-impregnated fiber capacitor dry-type bushing is obtained, and the barrier effect of the multi-layer capacitor pole plates arranged concentrically in the bushing capacitor core on the fluidity of the epoxy resin glue is eliminated to the greatest extent, the permeability and mechanical strength of the dry-type bushing are further improved, the risk of defects and cracks formed in the thick-wall capacitor core during curing shrinkage or thermal expansion and contraction is reduced, the electrical performance index and operation reliability of the product are improved, and the production qualification rate of the dry-type bushing is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of high-voltage bushings for power transmission and transformation, and in particular relates to a method for improving the production qualification rate of dry-type bushings. Background Art

[0002] At present, the dry high-voltage bushings used in the power transmission and transformation industry mainly include glue-impregnated crepe paper type and glass fiber wound type.

[0003] The current problems of the glue-impregnated crepe paper type are as follows: ①, the production process requires a large amount of crepe paper, all of which must be made of wood, which does not conform to the current environmental protection trend and fashion; ②, the vacuum drying insulation treatment cycle of crepe paper fiber is particularly long and the production cost is high; ③, it is difficult to completely penetrate the epoxy resin in the capillary fiber tube of the crepe paper fiber. In the later production, processing, transportation and operation process, the exposed epoxy part must be sealed and protected by a special container, otherwise the paper fiber will reabsorb moisture in the air, causing the dielectric loss of the bushing and increased local discharge. Long-term operation will cause bushing failure and collapse, posing a major hidden danger to the whole equipment; ④, the capacitor plates need to be arranged alternately between the crepe paper, and the tightness of the crepe paper rolling is difficult to control, which has an important impact on the accuracy of the electrode arrangement and the final epoxy resin infiltration degree, and requires high process equipment and workers' proficiency; ⑤, there are many electrode layers. If any layer of electrode arrangement is wrong or there are other hidden defects during the rolling process, the entire product will be scrapped, which is not convenient for mass industrial production.

[0004] Glass fiber winding type: ①. The product is wound in an open environment. The production process cannot be dry and insulated under vacuum conditions. The moisture contained in the insulating material itself and the moisture and impurities in the air cannot be removed, resulting in relatively large dielectric loss of the product. Long-term operation can easily lead to thermal collapse of the product; ②. The edge processing, flatness, concentricity and bonding performance of the aluminum foil metal capacitor electrode are poor, resulting in a large partial discharge of the product, often in the hundreds to thousands of picoules, which cannot be used with equipment that requires higher electrical performance;

[0005] Traditional capacitor plates are made of aluminum foil, which has a dense structure and is a non-permeable material. In addition, multiple layers of capacitor plates are often required in a casing according to the voltage level. This will cause the flow direction of the epoxy resin and the curing internal stress of the capacitor core to be blocked and shielded by the metal plate during the vacuum impregnation of epoxy resin (such as Figure 1 Schematic diagram of the traditional structure with all long plates arranged), it is easy to form air gaps, or the solidified internal stress cannot be released, resulting in delamination and defects, which often lead to partial discharge failure of the product or breakdown by withstand voltage. Summary of the invention

[0006] The purpose of the present invention is to provide a method for improving the production qualification rate of dry-type bushings; the method is characterized in that long and short plates are arranged alternately in the axial direction of the outer periphery of the dry-type bushings; the specific steps are as follows:

[0007] Step 1, cleaning the conductive rod or the mold core rod;

[0008] Step 2, firstly arrange a zero potential electrode that completely penetrates the axial direction near the outer peripheral surface of the conductive rod;

[0009] Step 3, first wrap a layer of synthetic fiber woven mesh on the outer peripheral surface of the zero potential electrode, and then arrange the first layer of long electrode plates that are completely axially penetrated; take the two end points of the first layer of long electrode plates as vertices, respectively set an oblique line at a certain angle to the middle of the axis, and based on the two oblique lines, arrange 2 to 5 layers of short electrodes at the upper and lower ends; then arrange the second long electrode plate; and by analogy, arrange the long and short electrodes alternately; wherein each electrode plate is separated by a synthetic fiber woven mesh; finally, arrange the two long electrode plates in an offset manner, and wrap them with more than one layer of synthetic fiber woven mesh to form a complete dry casing;

[0010] Step 4, glue-impregnated synthetic fiber mesh cloth, pouring epoxy resin glue liquid into one end of the dry bushing and flowing out from the other end, and the epoxy resin glue liquid flows longitudinally and transversely between the synthetic fiber mesh cloths; finally, a glue-impregnated fiber capacitor dry bushing is obtained.

[0011] The number of layers of the alternating arrangement of the long and short plates is determined according to the withstand voltage grade of the dry-type bushing.

[0012] The length of each long electrode plate from inside to outside is determined by the distance between the points on the two oblique lines at the location; the length of each short electrode plate remains unchanged; thus, a symmetrical jujube-shaped dry sleeve is formed.

[0013] The long and short pole plates are in the shape of synthetic fiber metal-plated conductive cloth sheets.

[0014] The synthetic fiber woven mesh cloth is a synthetic fiber metal-plated conductive cloth.

[0015] The angle of the oblique line arranged at a certain angle to the axis toward the middle is 8°-15°.

[0016] The long and short plates are alternately arranged and form a symmetrical jujube-shaped shape, which eliminates the barrier effect formed by the concentrically arranged multi-layer capacitor plates in the sleeve capacitor core on the fluidity of the epoxy resin glue to the greatest extent, further improves the permeability and mechanical strength of the dry sleeve, reduces the risk of defects and cracks in the thick-walled capacitor core during curing shrinkage or thermal expansion and contraction, and improves the product's electrical performance indicators and operational reliability.

[0017] The long and short plates of the glue-impregnated synthetic fiber capacitor dry sleeve design make the overall structure of the capacitor core completely permeable; firstly, the capacitor plate core of the design structure, the method of arranging the long and short capacitor plates alternately makes the capacitor core not form a completely closed space, but a semi-open structure, which can avoid to the greatest extent that during the glue injection process, the rate of rise of the glue surface between the capacitor plates remains consistent, and avoids the risk of defects caused by backflow and turbulence caused by inconsistent glue flow rates between layers; secondly, during the curing process of epoxy resin, due to the temperature difference between the inside and outside of the capacitor core, the curing speed of epoxy resin is inconsistent, resulting in curing shrinkage stress, especially the thicker symmetrical jujube-shaped in the middle of the capacitor core, which can make the epoxy resin glue between the layers of the capacitor core flow mutually, have a uniform osmotic pressure, eliminate the curing internal stress, make the capacitor core form an isotropic uniform material, avoid residual internal stress, form stratification and cracking defects, and greatly improve the product qualification rate and electrical performance.

[0018] The beneficial effect of the present invention is that the structure of the dry bushing designed by the present invention overcomes the defects in the manufacturing process of the above-mentioned existing dry bushing in terms of structure and process, greatly reduces the production process cycle of the product, improves the electrical performance of the product, can achieve the effect of zero partial discharge of the dry bushing, and can greatly improve the manufacturing qualification rate of the dry bushing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of a traditional structure composed entirely of long pole plates.

[0020] Figure 2 This is a schematic diagram of a new structure with zero-layer plates + alternating long and short plates.

[0021] Figure 3 for Figure 2 A partial enlarged view of . DETAILED DESCRIPTION

[0022] The present invention provides a method for improving the production qualification rate of dry-type casing; the present invention is described below in conjunction with the accompanying drawings and embodiments. Example

[0023] like Figure 2 , Figure 3 The new structure schematic diagram is shown as zero layer plate + long and short plates are arranged alternately. Long and short plates are arranged alternately in the axial direction of the outer periphery of the dry bushing, and the epoxy resin glue flows longitudinally and transversely between the synthetic fiber woven mesh cloth; finally, the glue-impregnated fiber capacitor dry bushing is obtained to improve the dry bushing production qualification rate; the specific steps are as follows:

[0024] Step 1, cleaning the conductive rod or the mold core rod;

[0025] Step 2, firstly arrange a zero potential electrode 3 which completely penetrates axially on the outer peripheral surface of the conductive rod 1;

[0026] Step 3, first wrap a layer of synthetic fiber woven mesh 2 on the outer peripheral surface of the zero potential electrode 3, and then arrange the first layer of long electrode plate 5 that completely penetrates axially; with the two end points of the first layer of long electrode plate 5 as vertices, set an oblique line at an angle of 35° to the axis to the middle, and then arrange the second long electrode plate 5 based on the two oblique lines; then arrange two layers of short electrodes 4 at the upper and lower ends, and finally, arrange two long electrode plates 5 in an offset manner; and wrap more than one layer of synthetic fiber woven mesh 2, wherein each electrode plate is separated by a synthetic fiber woven mesh 2; wherein the length of each long electrode plate from the inside to the outside is determined by the distance between the upper points of the two oblique lines at the location; the length of each short electrode plate remains unchanged; thereby forming a symmetrical jujube-shaped dry casing.

[0027] Step 4: Glue-impregnate the synthetic fiber mesh. Pour the epoxy resin glue into one end of the dry sleeve and let it flow out from the other end. The epoxy resin glue is longitudinally (such as Figure 1 , Figure 2 The vertical arrows in the middle) and horizontal arrows in the middle Figure 1 , Figure 2 The final result is the glue-impregnated fiber capacitor dry casing (as shown in the dashed line and horizontal arrow). Figure 2 as shown).

[0028] The number of layers of the long and short plates arranged alternately is determined according to the withstand voltage level of the dry bushing. This embodiment is designed for a 110kV high voltage transmission line.

[0029] The long and short pole plates are in the shape of synthetic fiber metal-plated conductive cloth sheets.

[0030] The synthetic fiber woven mesh cloth is a synthetic fiber metal-plated conductive cloth.

[0031] The specific instructions are as follows:

[0032] 1. The dry-type rubber-impregnated fiber capacitor bushing of the present invention is composed of a traditional long electrode plate arrangement (such as Figure 1 ) is changed to an alternating arrangement of long plates that are completely axially penetrated and short plates that are not completely axially penetrated (as shown in Figure 2 , 3 The purpose is to eliminate the barrier effect of the multi-layer capacitor plates arranged concentrically in the sleeve capacitor core on the fluidity of the epoxy resin glue to the greatest extent, further improve the permeability and mechanical strength of the dry sleeve, reduce the risk of defects and cracks in the thick-walled capacitor core during curing shrinkage or thermal expansion and contraction, and improve the product's electrical performance indicators and operational reliability;

[0033] 2. The long and short plates used for the dry bushing in the present invention are arranged according to the product voltage level, and zero potential electrodes are arranged near the conductive rods respectively, and then two layers of long electrodes, 3 to 5 layers of short electrodes, and one layer of long electrode are arranged outwards in sequence, and short electrodes and long electrodes are arranged alternately in sequence, and two layers of long electrodes are arranged on the outermost layer;

[0034] 3. The design of the long and short plates of the glue-impregnated synthetic fiber capacitor dry sleeve adopted by the present invention makes the overall structure of the capacitor core completely permeable. First, the capacitor plate core of the design structure, the method of arranging the alternating long and short capacitor plates makes the capacitor core not form a completely closed space, but a semi-open structure, which can avoid the rate of the glue surface rising between the capacitor plates to the greatest extent during the glue injection process, and avoid the risk of backflow and turbulence caused by inconsistent glue flow rates between layers, resulting in defects such as air inclusion; second, during the curing process of epoxy resin, due to the temperature difference between the inside and outside of the capacitor core, the curing speed of epoxy resin is inconsistent, resulting in curing shrinkage stress, especially in the thicker part in the middle of the capacitor core. After the method of arranging the long and short plates is adopted, the epoxy resin glue between the layers of the capacitor core can flow mutually, with a uniform osmotic pressure, eliminating the curing internal stress, and forming an isotropic uniform material for the capacitor core, avoiding residual internal stress, forming stratification and cracking defects, and greatly improving the product qualification rate and electrical performance.

Claims

1. A method for improving the production qualification rate of dry casing; characterized in that: Long and short plates are arranged alternately in the axial direction of the outer periphery of the dry bushing; the specific steps are as follows: Step 1, cleaning the conductive rod or the mold core rod; Step 2, firstly arrange a zero potential electrode that completely penetrates the axial direction near the outer peripheral surface of the conductive rod; Step 3, first wrap a layer of synthetic fiber woven mesh on the outer peripheral surface of the zero potential electrode, and then arrange the first layer of long electrode plates that are completely axially penetrated; take the two end points of the first layer of long electrode plates as vertices, respectively set an oblique line at a certain angle to the middle of the axis, and based on the two oblique lines, arrange 2 to 5 layers of short electrodes at the upper and lower ends; then arrange the second long electrode plate; and by analogy, arrange the long and short electrodes alternately; wherein each electrode plate is separated by a synthetic fiber woven mesh; finally, arrange the two long electrode plates in an offset manner, and wrap them with more than one layer of synthetic fiber woven mesh to form a complete dry casing; Step 4, glue-impregnated synthetic fiber mesh cloth, pouring epoxy resin glue liquid into one end of the dry bushing and flowing out from the other end, and the epoxy resin glue liquid flows longitudinally and transversely between the synthetic fiber mesh cloths; finally, a glue-impregnated fiber capacitor dry bushing is obtained.

2. A method for improving the production qualification rate of dry casing according to claim 1; characterized in that: The number of layers of the alternating arrangement of the long and short plates is determined according to the withstand voltage grade of the dry-type bushing.

3. A method for improving the production qualification rate of dry casing according to claim 1; characterized in that: The length of each long electrode plate from inside to outside is determined by the distance between the points on the two oblique lines at the location; the length of each short electrode plate remains unchanged; thus, a symmetrical jujube-shaped dry sleeve is formed.

4. A method for improving the production qualification rate of dry-type casing according to claim 1; characterized in that: The long and short pole plates are in the shape of synthetic fiber metal-plated conductive cloth sheets.

5. A method for improving the production qualification rate of dry-type casing according to claim 1; characterized in that: The synthetic fiber mesh is a mesh made of nylon, polypropylene or polytetrafluoroethylene and is plated with a metal conductive layer.

6. A method for improving the production qualification rate of dry-type casing according to claim 1; characterized in that: The angle of the oblique line arranged at a certain angle to the axis toward the middle is 8°-15°.

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