Oil-immersed vertical capacitor type insulation structure current transformer wrapping pretreatment process

Abstract

This invention relates to a pre-treatment process for wrapping an oil-immersed, upright, capacitively insulated current transformer, comprising the following steps: Step 1, placing a cardboard positioning fixture onto the straight section of the primary conductor; Step 2, placing insulating cardboard into the cardboard positioning groove within the cardboard positioning fixture; Step 3, moving the cardboard positioning fixture to the set position on the straight section and locking it; Step 4, wrapping the straight section using fiberless tape starting from the top, and when wrapping to any position of the cardboard positioning fixture, unscrewing the adjusting bolt to remove the cardboard positioning fixture; Step 5, wrapping the loop section of the primary conductor with shrink-wrap tape; Step 6, wrapping the loop section and the straight section entirely with crepe paper; Step 7, wrapping the zero-shield starting from the outside of the primary conductor. This invention is designed for a special current transformer structure where each end screen is stacked sequentially from the inside out and extends towards the loop section of the primary conductor, ensuring a regular overall cross-sectional shape of the straight section of the primary conductor.

Description

Technical Field

[0001] This invention relates to the field of current transformer manufacturing, specifically to a pre-treatment process for wrapping an oil-immersed, upright, capacitive-type insulated current transformer. Background Technology

[0002] In existing oil-immersed vertical current transformers, taking a 35kV current transformer as an example, the primary winding (high-voltage electrode) and secondary winding (low-voltage electrode) are two mutually perpendicular links, and the shapes of the high- and low-voltage electrodes are very irregular. This results in a chaotic electric field distribution and low main insulation utilization in such transformers. To improve the electric field and increase the main insulation utilization of such oil-immersed vertical current transformers, new insulation structures have emerged in the prior art. For example, patent CN204991430U discloses an oil-immersed vertical capacitive insulation structure current transformer, which sets some intermediate capacitor screens in the insulation, so that a series capacitor is formed between the high potential and the ground potential, thereby achieving a uniform electric field and making full use of the insulating medium, thus improving the main insulation utilization. However, in actual production, it was found that when the straight section of the primary conductor of the current transformer is wrapped with a zero shield, insulation layer, end shield, etc., the diameter of the straight section is easily irregular if a traditional circular cross-section structure is used, because the various end shields are stacked sequentially from the inside to the outside and extend into the ring of the primary conductor. That is, the cross-sectional shape after wrapping is not circular. This places high demands on the wrapping personnel. Furthermore, if the cross-sectional shape of the entire straight section changes irregularly along the axial direction, the subsequent partial discharge test will fail. Summary of the Invention

[0003] The purpose of this invention is to provide a pre-treatment process for wrapping an oil-immersed, upright, capacitor-type insulated current transformer. This process is designed for a special current transformer structure where each end panel is stacked sequentially from the inside out and extends into the ring of the primary conductor. Before wrapping the zero-side panel, cardboard and cardboard positioning fixtures are used to pre-shape the straight section of the primary conductor. Then the zero-side panel is wrapped. This makes it easy to control the spacing between the side walls in the four directions (front, back, left, and right) of the straight section of the primary conductor, thereby ensuring that the overall cross-sectional shape of the straight section is relatively regular.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A pre-treatment process for wrapping an oil-immersed, upright, capacitor-type insulated current transformer includes a primary conductor, which comprises a straight section and a ring section. The straight section has a zero screen, a ground screen, and multiple end screens on its outer side. The multiple end screens are located between the zero screen and the ground screen and are stacked sequentially from the inside out, extending towards the ring section of the primary conductor. The process also includes a cardboard positioning fixture, which comprises a square fixture frame. Each side wall of the fixture frame has an adjusting bolt and a positioning plate with a cardboard positioning groove in its center. The front end of the adjusting bolt passes through the fixture frame and is fixedly connected to the corresponding positioning plate. The cardboard positioning grooves on each positioning plate have the same size.

[0006] The pretreatment process includes the following steps:

[0007] Step 1: Adjust the adjusting bolt of the cardboard positioning fixture backward to the set position, and then put the cardboard positioning fixture on the straight part of the primary conductor;

[0008] Step 2: Place the insulating cardboard into the cardboard positioning fixture and embed it into the cardboard positioning groove of the corresponding side positioning plate;

[0009] Step 3: Move the cardboard positioning fixture to the set position on the straight section, and then turn the adjusting bolt to drive the positioning plate forward so that the insulating cardboard abuts against the straight section of the primary conductor until the cardboard positioning fixture is locked in position;

[0010] Step 4: After the insulating cardboard is fixed on the straight section of the primary conductor by multiple cardboard positioning fixtures, the straight section is wrapped with fiberless tape starting from the top. When the tape reaches any cardboard positioning fixture, the adjusting bolt is turned backward to remove the cardboard positioning fixture.

[0011] Step 5: After the straight section is wrapped, the loop of the primary conductor is wrapped with shrink tape;

[0012] Step Six: The entire ring and straight section is wrapped with crepe paper;

[0013] Step 7: Begin wrapping a zero screen around the outside of the primary conductor.

[0014] The front end of the adjusting bolt is threadedly connected to the positioning plate.

[0015] In step four, after the insulating cardboard is fixed to the straight section of the primary conductor by multiple cardboard positioning fixtures, the straight section is wrapped with one layer of fiberless tape from the top.

[0016] In step four, crepe paper is added to the repositioned recess on the straight section.

[0017] In step five, the loop of the primary conductor is wrapped with one layer of shrink tape.

[0018] In step six, the entire ring section and straight section are wrapped with 10 layers of crepe paper in a semi-folded manner.

[0019] The advantages and positive effects of this invention are as follows:

[0020] 1. This invention designs a special current transformer structure in which each end screen is stacked sequentially from the inside out and extends into the ring of the primary conductor. Before wrapping the zero screen, the straight part of the primary conductor is pre-shaped using cardboard and cardboard positioning fixtures. Then the zero screen is wrapped. In this way, the spacing between the side walls in the four directions of front, back, left and right of the straight part of the primary conductor is easy to control, thereby ensuring that the overall cross-sectional shape of the straight part is relatively regular.

[0021] 2. The cardboard positioning fixture of the present invention is simple and convenient to operate, and at the same time can ensure that the cardboard specifications and positions on each side of the straight section of the primary conductor are consistent, thereby further ensuring that the cross-sectional shape of the straight section is regular after wrapping. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the oil-immersed vertical current transformer structure that this invention addresses.

[0023] Figure 2 for Figure 1 AA view of existing current transformer products in China

[0024] Figure 3 This is an AA view of the current transformer product according to the present invention.

[0025] Figure 4 This is a top view of the cardboard positioning fixture used in this invention.

[0026] Figure 5 for Figure 4 A schematic diagram showing the usage status of the cardboard positioning fixture.

[0027] Among them, 1 is the primary conductor, 101 is the straight section, 102 is the ring section, 103 is the triangular zone, 2 is the main insulation, 201 is the zero screen, 202 is the first end screen, 203 is the second end screen, 204 is the third end screen, 205 is the fourth end screen, 206 is the ground screen, 3 is the secondary coil, 4 is the cardboard positioning fixture, 401 is the fixture frame, 402 is the positioning plate, 403 is the adjusting bolt, and 5 is the insulating cardboard. Detailed Implementation

[0028] The invention will now be described in further detail with reference to the accompanying drawings.

[0029] like Figures 1-2As shown, the oil-immersed upright capacitor-type insulated current transformer of the present invention includes a primary conductor 1 and a main insulation 2. The primary conductor 1 includes a straight section 101 and a ring section 102, and a triangular zone 103 is formed at the junction between the straight section 101 and the ring section 102. The straight section 101 is provided with a zero screen 201, a first end screen 202, a second end screen 203, a third end screen 204, a fourth end screen 205 and a ground screen 206 in sequence on the outside. The end screens are stacked in sequence from the inside to the outside and extend to the ring section 102 of the primary conductor 1. The wrapping process in the prior art is to directly wrap the zero screen 201 on the outside of the straight section 101 of the primary conductor 1, and then wind the insulation layers and end screens in sequence. The above is a well known technology in the art. For example, see patent CN204991430U.

[0030] However, in actual production, it was found that the above-mentioned bandaging process was affected by factors such as different people applying different bandaging force, the relatively long length of the straight section 101, and the misalignment of the end panels during bandaging. If the straight section 101 adopts... Figure 2 As shown in the conventional circular cross-sectional shape, after wrapping, the diameter of each part of the straight section 101 is easily different. According to actual production statistics, 3 to 4 out of 10 products have this problem, resulting in a relatively high rework rate. In addition, if the cross-sectional shape of the entire straight section 101 changes irregularly along the axial direction, the subsequent partial discharge test will fail.

[0031] like Figure 3 As shown, after comprehensive consideration, the present invention decides that the straight section 101 adopts... Figure 3 The approximate rectangular shape shown allows for easy control of the spacing between its side walls in the four directions (front, back, left, and right), thus ensuring... Figure 1 The overall cross-sectional shape of the straight section 101 shown is relatively regular.

[0032] like Figure 4 As shown, in the process of this invention, before wrapping the zero screen 201, the straight section 101 of the primary conductor 1 is pre-shaped using insulating paperboard 5 so that the cross-section of the entire straight section 101 is a regular, approximately rectangular shape. Then, the straight section 101 is wrapped with one layer of fiberless tape, and then the zero screen 201 is wrapped. At this time, the four side walls of the straight section 101 of the primary conductor 1 are strictly limited by the corresponding insulating paperboard 5, thereby ensuring that the cross-section of the wrapped straight section 101 is an approximately rectangular shape with a relatively regular change.

[0033] like Figure 4As shown, when pre-processing the straight section 101 of the primary conductor 1, the present invention uses a cardboard positioning fixture 4 to assist in positioning the insulating cardboard 5 on each side, thereby ensuring that the insulating cardboard 5 on each side of the straight section 101 is in the same position and will not move. The cardboard positioning fixture 4 includes a square fixture frame 401, and each side wall of the fixture frame 401 is provided with an adjusting bolt 403 and a positioning plate 402 with a cardboard positioning groove. The front end of the adjusting bolt 403 passes through the fixture frame 401 and is fixedly connected to the corresponding positioning plate 402. Tightening the adjusting bolt 403 can drive the positioning plate 403 to move. The cardboard positioning grooves on each positioning plate 402 are the same size, so only insulating cardboard 5 of the same specification can be placed in the cardboard positioning groove. Then, each positioning plate 402 moves forward by tightening the corresponding adjusting bolt 403 so that the insulating cardboard 5 abuts against the straight part 101 of the primary conductor 1. During adjustment, it is necessary to ensure that the pressure of the insulating cardboard 5 will not damage the primary conductor 1, and that the two ends of the cardboard positioning groove do not contact the primary conductor 1. It is only necessary to ensure that the fixture can be locked and fixed.

[0034] like Figure 5 As shown, the present invention can, as needed, provide multiple cardboard positioning fixtures 4 along the axial direction on the straight portion 101 of the primary conductor 1 to ensure the accurate positioning of the insulating cardboard 5 on the outer side of the entire straight portion 101, while simultaneously... Figure 4 As shown, the corner bend diameter R of the straight section 101 is equal. When wrapping, when the operator wraps the cardboard positioning fixture 4, he only needs to turn each adjusting bolt 403 backward to remove the fixture. At the same time, the remaining cardboard positioning fixtures 4 remain in the positioning state, thus ensuring that each insulating cardboard 5 will not move during the wrapping process.

[0035] like Figure 4 As shown, in this embodiment, the front end of the adjusting bolt 403 is threadedly connected to the positioning plate 402, so the positioning plate 403 can be replaced according to actual needs. When using this invention, the dimensions, quantity, and arrangement of the cardboard corresponding to products with various primary current specifications are clearly defined.

[0036] The process of this invention includes the following steps:

[0037] Step 1: Adjust the adjusting bolt 403 of the cardboard positioning fixture 4 backward to the set position, and then put the cardboard positioning fixture 4 on the straight part 101 of the primary conductor 1. At this time, the cardboard positioning fixture 4 does not clamp the primary conductor 1, and sufficient space needs to be left for the insulating cardboard 5 to be inserted.

[0038] Step 2: Place the insulating cardboard 5 into the cardboard positioning fixture 4 and embed it into the cardboard positioning groove of the corresponding side positioning plate 402. It is necessary to ensure that the insulating cardboard 5 does not sway left and right in the cardboard positioning groove, and can move freely in and out of the cardboard positioning groove.

[0039] Step 3: Move the cardboard positioning fixture 4 to the set position on the straight section 101, and then turn the adjusting bolt 403 to drive the positioning plate 402 forward so that the insulating cardboard 5 abuts against the straight section 101 of the primary conductor 1. At this time, it is necessary to control the force by turning the adjusting bolt 403 to ensure that the cardboard positioning fixture 4 is locked without damaging the insulating cardboard 5 and the primary conductor 1.

[0040] Step 4: After the insulating cardboard 5 is fixed to the straight section 101 of the primary conductor 1 using multiple cardboard positioning fixtures 4, the straight section 101 is wrapped with a single layer of fiberless tape, starting from the top. When wrapping to any position of a cardboard positioning fixture 4, the operator unscrews the adjusting bolt 403 to remove the cardboard positioning fixture 4, and then continues wrapping until the entire straight section 101 is wrapped. Additionally, during the wrapping process, crepe paper is added to the repositioning recesses on the straight section 101. The size and quantity of crepe paper are clearly specified, requiring the padding to be tight and the transition smooth. The single layer of fiberless tape and the crepe paper padding are both technologies known in the art.

[0041] Step 5: The loop portion 102 of the primary conductor 1 is wrapped with a shrinkable fabric tape, which is a technology known in the art.

[0042] Step 6: The ring portion 102 and the straight portion 101 are wrapped together with 10 layers of crepe paper.

[0043] Step 7: Then, start wrapping the zero screen 201 around the outside of the primary conductor 1. The subsequent process is the same as CN204991430U.

Claims

1. A pre-treatment process for wrapping an oil-immersed, upright, capacitor-type insulated current transformer, comprising a primary conductor, the primary conductor including a straight section and a loop section, and a neutral screen, a ground screen, and multiple end screens provided on the outer side of the straight section, wherein the multiple end screens are located between the neutral screen and the ground screen and are stacked sequentially from the inside to the outside extending towards the loop section of the primary conductor, characterized in that: The device includes a cardboard positioning fixture (4), which includes a square fixture frame (401). Each side wall of the fixture frame (401) is provided with an adjusting bolt (403) and a positioning plate (402) with a cardboard positioning groove. The front end of the adjusting bolt (403) passes through the fixture frame (401) and is fixedly connected to the corresponding positioning plate (402). The cardboard positioning grooves on each positioning plate (402) are the same size. The pretreatment process includes the following steps: Step 1: Adjust the adjusting bolt (403) of the cardboard positioning fixture (4) backward to the set position, and then put the cardboard positioning fixture (4) onto the straight part (101) of the primary conductor (1); Step 2: Place the insulating cardboard (5) into the cardboard positioning fixture (4) and embed it into the cardboard positioning groove of the corresponding side positioning plate (402); Step 3: Move the cardboard positioning fixture (4) to the set position on the straight section (101), and then turn the adjusting bolt (403) to drive the positioning plate (402) forward so that the insulating cardboard (5) abuts against the straight section (101) of the primary conductor (1) until the position of the cardboard positioning fixture (4) is locked. Step 4: After the insulating cardboard (5) is fixed on the straight section (101) of the primary conductor (1) by multiple cardboard positioning fixtures (4), the straight section (101) is wrapped with fiberless tape starting from the top. When the wrapping reaches any cardboard positioning fixture (4) position, the adjusting bolt (403) is turned backward to remove the cardboard positioning fixture (4). Step 5: After the straight section (101) is wrapped, the loop section (102) of the primary conductor (1) is wrapped with shrink tape; Step 6: The entire ring portion (102) and straight portion (101) are wrapped with crepe paper; Step 7: Start wrapping a zero screen (201) around the outside of the primary conductor (1).

2. The pretreatment process for wrapping oil-immersed upright capacitive type insulated current transformer according to claim 1, characterized in that: The front end of the adjusting bolt (403) is threadedly connected to the positioning plate (402).

3. The pretreatment process for wrapping oil-immersed upright capacitive type insulated current transformer according to claim 1, characterized in that: In step four, after the insulating cardboard (5) is fixed on the straight section (101) of the primary conductor (1) by multiple cardboard positioning fixtures (4), the straight section (101) is wrapped from the top using a layer of nonwoven tape.

4. The pretreatment process for wrapping oil-immersed upright capacitive type insulated current transformer according to claim 1, characterized in that: In step four, crepe paper is added to the repositioning recess on the straight section (101).

5. The pretreatment process for wrapping oil-immersed upright capacitive type insulated current transformer according to claim 1, characterized in that: In step five, the loop portion (102) of the primary conductor (1) is wrapped with a shrink tape layer.

6. The pretreatment process for wrapping oil-immersed upright capacitive type insulated current transformer according to claim 1, characterized in that: In step six, the ring portion (102) and the straight portion (101) are wrapped together with 10 layers of crepe paper.

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