Assembly method of C-type three-phase voltage transformer

Abstract

The invention discloses a C-type head three-phase voltage transformer assembly method, which comprises: fixing the coil body after vacuum drying in a casting mold, then installing three corresponding low-voltage shielding nets A, B, and C, connecting the primary winding to the fuse shielding net through a primary lead terminal insert; connecting the secondary terminal and the secondary winding and fixing them through a secondary cover plate of the mold, adjusting the insulation distance between the low-voltage shielding net and the fuse shielding net, and using epoxy resin vacuum casting and curing to form an insulator, wherein three primary insulating columns at equal vertical distances on the upper part of the insulator are truncated cone terminals of the same shape; and spraying a layer of metal conductive paint on the lower and middle surfaces of the insulator after uniform sandblasting, wherein the metal conductive paint is connected to the ground terminal. The method does not need to specially install other numerous electrical accessories, saves time and labor, and avoids the occurrence of ferromagnetic resonance failure of the voltage transformer from the assembly method.

Description

Technical Field

[0001] The invention relates to the technical field of high-voltage measurement or relay protection equipment for electric power systems, and in particular to an assembly method for a C-type three-phase voltage transformer. Background Art

[0002] Voltage transformers mainly play measurement and protection functions in power systems or electrical control systems. In order to achieve the detuning function of the power system and miniaturize the switch cabinet and facilitate overhaul and maintenance, voltage transformers equipped with detuning devices are usually used. They are mainly composed of single-phase voltage transformers, detuning devices, insulating pillars, external fuses, contacts, etc., but there are many components, complex installation, cumbersome maintenance, many quality control points, high cost, unreliable insulation, and time-consuming and labor-intensive assembly. Summary of the invention

[0003] The purpose of the present invention is to provide a C-type head three-phase voltage transformer assembly method, which does not require the special installation of other numerous electrical accessories, saves time and labor, and avoids the occurrence of voltage transformer ferromagnetic resonance failure from the assembly method.

[0004] To achieve the above purpose, the present application proposes a C-type head three-phase voltage transformer assembly method, comprising:

[0005] The secondary winding and the primary winding are concentrically wound on two resin insulation frames using winding equipment, and then sleeved on the core column. After insulation and buffer wrapping, they form the A and C phase coil bodies respectively. Two of the A and C phase coils are connected together to form the B phase.

[0006] The vacuum-dried coil body is fixed in the casting mold, and then the three corresponding low-voltage shielding nets A, B, and C are installed, and the primary winding is connected to the fuse shielding net through the primary lead terminal insert, and the fuse shielding net is fixed to the mold core mold bolt;

[0007] The secondary terminal and the secondary winding are connected and fixed through the secondary cover of the mold, and the insulation distance between the low-voltage shielding net and the fuse shielding net is adjusted. The insulator is formed by vacuum casting and curing of epoxy resin. The three primary insulating columns at the upper part of the insulator with equal vertical distance are frustum-type terminals of the same shape, commonly known as C-type heads;

[0008] After uniformly sandblasting the lower surface of the insulator, a layer of metal conductive paint is sprayed, and the metal conductive paint is connected to the grounding terminal.

[0009] Furthermore, the low-voltage shielding net is assembled as follows: the upper edge of the cylindrical metal wire mesh a is folded outward, and the two sides of the lower edge are soldered to the embedded nuts through metal wires to form a left-right symmetrical structure, and the exposed end faces of the embedded nuts are connected to the metal conductive paint.

[0010] Furthermore, the fuse shielding net is assembled by sleeve one end of the cylindrical metal wire mesh b onto the outer periphery of the screw sleeve and connecting them by argon arc welding.

[0011] Furthermore, during the pouring process, a square flange is formed at the root of the three primary insulating columns, and ribs are installed at the bottom of both sides of the square flange. The ribs are also fixedly connected to the insulator, and holes are opened around the square flange.

[0012] Furthermore, the gap between the fuse sealed in the primary insulating column and the primary high-voltage cavity is potted with polyurethane resin.

[0013] Furthermore, one end of the fuse with a thread passes through the primary high-voltage cavity and is fixed in the screw sleeve, and the other end is exposed outside.

[0014] Furthermore, the back of the insulator is cast as a semicircular arc transition, and the front is cast as an inclined transition.

[0015] Furthermore, a secondary wiring platform is arranged at the bottom of the front of the insulator, and the secondary wiring platform protrudes in a straight triangular prism shape in the horizontal direction, on which a secondary terminal is arranged, and a grounding terminal is arranged on the upper side of the secondary wiring platform.

[0016] Compared with the prior art, the above technical solution adopted by the present invention has the following advantages:

[0017] 1. The three-phase voltage transformer obtained by this method has a small size and a reasonable detuning function structure: the primary high-voltage insulation column and the fuse are encapsulated with polyurethane resin to form an integrated structure, making the product structure more compact and small in size; the fuse end of the product is exposed, and it is plug-and-play with the high-voltage busbar of the switch cabinet. The detuning function structure is reasonable, integrating the functions of fuse protection and conductive device, and is more suitable for the matching use of new voltage transformer switch cabinets;

[0018] 2. Easy installation and maintenance: When installing and using the product, you only need to insert the transformer into the switch cabinet according to the phase sequence and fix the bolts through the flange holes. There is no need to install other electrical accessories, which effectively saves the assembly time of the switch cabinet. The product is easier to repair and does not require special maintenance work.

[0019] 3. Stable insulation, small partial discharge, and safe operation: The fuse shielding net and the low-voltage shielding net are integrally cast with epoxy resin material, and the common shielding effect of the surface sprayed metal conductive layer makes the transformer insulation shielding reliable, the high and low voltage electric fields are evenly distributed, the partial discharge is small, and the safe operation of the product is ensured. The occurrence of ferromagnetic resonance failure of the voltage transformer is avoided from the assembly method, and the assembly efficiency is improved, saving time and effort. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1This is a schematic diagram of the internal structure of a C-type three-phase voltage transformer;

[0021] Figure 2 This is the main view of the external structure of the C-type three-phase voltage transformer;

[0022] Figure 3 This is the external structure side view of the C-type three-phase voltage transformer;

[0023] Figure 4 This is a top view of the external structure of a C-type three-phase voltage transformer;

[0024] Figure 5 This is the structural diagram of the fuse shielding network;

[0025] Figure 6 This is the structural diagram of the low-voltage shielding network.

[0026] Among them: 1. Iron core; 2. Secondary winding; 3. Primary winding; 4. Low-voltage shielding net; 5. Fuse shielding net; 6. Primary insulating column; 7. Fuse; 8. Primary high-voltage cavity; 9. Insulator; 10. Secondary terminal; 11. Grounding terminal; 12. Through hole; 13. Rib plate; 14. Embedded nut; 15. Metal mesh a; 16. Metal wire; 17. Metal mesh b; 18. Screw sleeve; 19. Square flange; 20. Secondary terminal block; 21. Insulation frame. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application, that is, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0028] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0029] Example 1

[0030] like Figure 1-6As shown, this embodiment provides a C-type three-phase voltage transformer obtained by the above method, specifically comprising: an insulator 9 with a three-phase coil body built in, three primary insulating columns 6 extending upward are provided on the top of the insulator 9, a primary high-voltage cavity 8 is opened in each primary insulating column 6, a fuse shielding net 5 is provided on the periphery of the primary high-voltage cavity 8, and a fuse 7 is installed in the primary high-voltage cavity 8; a low-voltage shielding net 4 concentric with the fuse shielding net 5 is embedded in the bottom of each primary insulating column 6, and the diameter of the low-voltage shielding net 4 is larger than the diameter of the fuse shielding net 5; the outer surface of the lower middle part of the insulator 9 is evenly sandblasted and then sprayed with a layer of metal conductive paint, and the metal conductive paint is connected to the grounding terminal 11 located on the insulator. The low-voltage shielding net 4 is used to shield the primary high voltage outside the low-voltage electric field and make the low-voltage electric field at the same low potential; the fuse shielding net 5 is used to shield the primary high voltage electric field within the primary high-voltage cavity 8 and make the high voltage electric field evenly distributed;

[0031] The insulator 9 is a bilaterally symmetrical structure, and the three primary insulating columns 6 on the top are A phase, B phase and C phase from left to right, which is convenient for the phase sequence arrangement of the switch cabinet. It not only serves as the installation of the fuse, but also ensures a uniform electric field around it and has sufficient mechanical strength. The middle of the insulator 9 is a horizontally arranged square flange 19 with through holes 12 at the four corners, which serves as a fixing for the insulation of the primary high-voltage terminal. The lower back of the insulator 9 is a semicircular arc transition, and the front is a bevel transition, which further increases the electrical insulation distance between phases and the insulation distance relative to the ground, and improves the insulation level of the product. There are ribs on both sides. 13. Ensure that the primary high-voltage terminal has sufficient mechanical strength during installation. The gap between the fuse 7 sealed in each primary insulating column 6 and the primary high-voltage cavity 8 is potted with polyurethane resin. The threaded end of the fuse 7 passes through the primary high-voltage cavity 8 and is fixed in the screw sleeve 18, and the other end is exposed to the outside. It is plug-and-play with the high-voltage busbar of the switch cabinet, integrating the functions of fuse protection and conductive devices. It is a primary conductive connection method that is different from the American elbow, realizing flexible electrical contact with the high-voltage busbar of the switch cabinet, ensuring effective electrical contact with the primary high-voltage fuse, and making the whole have sufficient mechanical strength. A low-voltage shielding net 4 concentric with the fuse shielding net 5 is embedded at the bottom of each primary insulating column 6. Except for the primary insulating column 6, the upper plane of the square flange 19 and the secondary terminal 10, the remaining surfaces of the insulator 9 are uniformly sandblasted and then sprayed with a layer of metal conductive paint. The metal conductive paint is connected to the grounding terminal 11 located on the insulator to achieve effective shielding of the low-voltage electric field.

[0032] A secondary wiring platform 20 is provided in the middle of the front bottom of the insulator 9. The secondary wiring platform 20 protrudes laterally in the shape of a straight triangular prism, and a secondary terminal 10 is provided on it for the convenience of users' secondary wiring. A grounding terminal 11 is provided on the secondary wiring platform 20 for the convenience of grounding.

[0033] When the product is in use, you only need to insert the transformer into the switch cabinet according to the phase sequence, fix the bolts through the flange holes, and finally connect the secondary cables. There is no need to install other numerous electrical accessories to achieve the detuning protection function, which effectively saves the time for completing the voltage transformer assembly work, and then saves the assembly time of the switch cabinet. The product is easier to overhaul and does not require special maintenance work.

[0034] The present invention adds a fuse shielding net 5 and a low-voltage shielding net 4, which are integrally cast with an epoxy resin material, and has a common shielding effect of a metal conductive layer sprayed on the surface, so that the insulation shielding of the transformer is reliable, the high and low voltage electric fields are evenly distributed, the partial discharge is small, and the safe operation of the product is guaranteed. It is used for voltage measurement and protection, and the occurrence of ferromagnetic resonance failure of the voltage transformer is avoided from a structural point of view.

[0035] The product is made of epoxy resin vacuum casting and has the advantages of small size, reasonable structure of detuning function, easy installation, stable insulation, small partial discharge, safe operation and easy maintenance. It can be widely used in supporting new switch cabinets.

[0036] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A C-type three-phase voltage transformer assembly method, characterized in that: include: The secondary winding and the primary winding are concentrically wound on two resin insulation frames using winding equipment, and then sleeved on the core column. After insulation and buffer wrapping, they form the A and C phase coil bodies respectively. Two of the A and C phase coils are connected together to form the B phase. The vacuum-dried coil body is fixed in the casting mold, and then the three corresponding low-voltage shielding nets A, B, and C are installed, and the primary winding is connected to the fuse shielding net through the primary lead terminal insert, and the fuse shielding net is fixed to the mold core mold bolt; The secondary terminal and the secondary winding are connected and fixed through the secondary cover of the mold, the insulation distance between the low-voltage shielding net and the fuse shielding net is adjusted, and the insulator is formed by vacuum casting and curing of epoxy resin. The three primary insulating columns at the upper part of the insulator with equal vertical distance are frustum-type terminals of the same shape; After uniformly sandblasting the lower surface of the insulator, a layer of metal conductive paint is sprayed, and the metal conductive paint is connected to the grounding terminal; The low-voltage shielding net is assembled as follows: the upper edge of the cylindrical metal wire mesh a is folded outward, and the two sides of the lower edge are soldered to the embedded nuts through metal wires to form a left-right symmetrical structure, and the exposed end surface of the embedded nut is connected to the metal conductive paint; The assembly method of the fuse shielding net is: one end of the cylindrical metal wire mesh b is sleeved on the outer periphery of the screw sleeve and connected by argon arc welding; During the pouring process, a square flange is formed at the root of the three primary insulating columns. Ribs are installed at the bottom of both sides of the square flange. The ribs are also fixedly connected to the insulator. Holes are opened around the square flange.

2. The C-type three-phase voltage transformer assembly method according to claim 1, characterized in that: The gap between the fuse sealed in the primary insulating column and the primary high-voltage cavity is potted with polyurethane resin.

3. The C-type three-phase voltage transformer assembly method according to claim 1, characterized in that: Pass the threaded end of the fuse through the primary high-voltage cavity and fix it in the screw sleeve, leaving the other end exposed.

4. The C-type three-phase voltage transformer assembly method according to claim 1, characterized in that: The back of the insulator is cast as a semicircular arc transition, and the front is cast as an inclined surface transition.

5. The C-type three-phase voltage transformer assembly method according to claim 1, characterized in that: A secondary wiring platform is arranged at the bottom of the front of the insulator. The secondary wiring platform protrudes in a horizontal direction in the shape of a straight triangular prism, on which a secondary terminal is arranged. A grounding terminal is arranged on the upper side of the secondary wiring platform.

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