Three-phase combined transformer interphase connection structure and three-phase combined transformer

Abstract

The utility model relates to a three-phase combined type transformer interphase connection structure and a three-phase combined type transformer, and belongs to the field of transformer manufacturing. According to the phase-to-phase connection structure of the three-phase combined type transformer, a pipe joint is made of a low-magnetic steel material, a plurality of fixing plates which are symmetrically and oppositely arranged in pairs are welded to the inner wall of the pipe joint, and L-shaped wire clamps and plate-shaped wire clamps are installed on the fixing plates; a pipe joint end flange and a metal corrugated pipe end flange are arranged at the joint of the pipe joint and the metal corrugated pipe respectively, fixing lugs are arranged on the peripheral edges of the pipe joint end flange and the metal corrugated pipe end flange, and a full-thread stud penetrates into one set of fixing lugs located on the same horizontal line. According to the three-phase combined transformer, three single-phase transformers are combined and connected into a whole by adopting the interphase connecting structure. According to the utility model, the matching problem in the in-place installation process of the transformer is reduced, the lead can be doubly fixed, and the problems of mechanical strength, electrical insulation margin and the like of an interphase connection structure are effectively solved.

Description

Technical Field

[0001] The utility model relates to a large-capacity three-phase combined transformer inter-phase connection structure and a three-phase combined transformer, belonging to the technical field of transformer manufacturing. Background Art

[0002] The power transformer is the main electrical equipment in the power grid. It is a static induction device that uses the principle of electromagnetic induction to convert and transmit AC power between two or more windings at the same frequency.

[0003] Power transformers are categorized by the number of phases into single-phase and three-phase transformers. Three-phase transformers include three-phase core-type transformers and three-phase combination transformers. The core of a three-phase core-type transformer is constructed as a single unit (e.g., three-phase five-leg, three-phase four-frame), while a three-phase combination transformer is a circuit consisting of three single-phase transformers. The main magnetic flux of each single-phase transformer core leg forms a separate magnetic circuit, independent of the magnetic circuits of the other two single-phase transformers. Three-phase core-type transformers are commonly produced and used, are relatively inexpensive, and occupy a smaller installation area. Generally, three-phase core-type transformers are used. However, in situations where there are special requirements for the transformer's mechanical properties, large capacity requirements, or transportation restrictions, a three-phase combination transformer may be considered to facilitate long-distance transportation and on-site installation.

[0004] The current three-phase combined transformer, when combined with three single-phase transformers, has technical problems such as low mechanical strength of the phase connection structure, insufficient insulation margin, inability to guarantee electrical insulation performance, and easy overheating of the transformer during operation. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a three-phase combined transformer interphase connection structure and a three-phase combined transformer. The technical solutions adopted by the present invention are as follows:

[0006] The interphase connection structure of a three-phase combined transformer includes a metal bellows and a pipe joint fixedly connected to both ends of the metal bellows. The pipe joint is made of low-magnetic steel, and a plurality of symmetrically arranged fixing plates are welded on the inner wall of the pipe joint. One end of an L-shaped wire clamp is fixedly connected to the fixing plate, and the other end of the L-shaped wire clamp is fixedly connected to one end of a plate-shaped wire clamp. The other adjacent ends of the pair of plate-shaped wire clamps are provided with a buckle structure; the connection between the pipe joint and the metal bellows is respectively provided with a pipe joint end flange and a metal bellows end flange, and the outer peripheral edges of the pipe joint end flange and the metal bellows end flange are provided with a plurality of corresponding fixing ears, and a group of fixing ears on the same horizontal line are inserted into a group of fixing ears, and a flat washer, a spring washer and a pair of second nuts are installed on the full-threaded studs in sequence from the metal bellows end flange. A flat washer, a spring washer and a single second nut are installed on the full-threaded studs in sequence from the pipe joint end flange.

[0007] Preferably, the two low-voltage leads pass through the pipe joint and the metal bellows on the low-pressure side, and the neutral point lead passes through the pipe joint and the metal bellows on the high-pressure side. Both the low-voltage lead and the neutral point lead pass through the buckle structure provided by a pair of plate-shaped wire clamps located in the pipe joint for clamping and fixing.

[0008] Preferably, the low-voltage lead end is fixedly connected to a stacking terminal head end by crimping, and the other stacking terminal head end is fixedly connected to one end of the low-voltage copper busbar by crimping. The neutral point lead end is fixedly connected to a stacking terminal head end by crimping, and the other stacking terminal head end is fixedly connected to one end of the neutral point lead connector by crimping. The stacking end of the stacking terminal is provided with a fourth through hole, and the stacking ends of a pair of stacking terminals overlap together. After the fourth bolt passes through the fourth through hole, the pair of stacking terminals are fastened by the fourth nut.

[0009] Preferably, a first internal threaded hole is formed on the fixing plate, and a first through hole and a second through hole are respectively formed at both ends of the L-shaped wire clamp, and the first bolt passes through the first through hole at the upper end of the L-shaped wire clamp and is screwed into the first internal threaded hole; a third through hole is formed at one end of the plate-shaped wire clamp, and the third bolt passes through the second through hole at the lower end of the L-shaped wire clamp and the third through hole of the plate-shaped wire clamp, and the threaded end of the third bolt is screwed into the third nut.

[0010] Preferably, the metal bellows is made of stainless steel.

[0011] The three-phase combined transformer comprises an A-phase single-phase transformer, a B-phase single-phase transformer and a C-phase single-phase transformer, wherein the A-phase single-phase transformer, the B-phase single-phase transformer and the C-phase single-phase transformer are fixedly connected into one body using the aforementioned three-phase combined transformer inter-phase connection structure.

[0012] The utility model has the following advantages:

[0013] Adjustable metal bellows have the advantages of reliable fastening and flexible adjustment. The utility model realizes a flexible connection between three single-phase transformers by designing metal bellows in the interphase connection structure, effectively reducing the matching problems during the installation process of the transformers. After the three single-phase transformers are connected, they are fixed by fully threaded studs and a second nut with a flat washer and a spring washer, further enhancing the mechanical strength of the interphase connection structure. Welding a fixing plate and installing a buckle structure wire clamp in the pipe joint can double-fix the lead wire, ensuring electrical insulation and increasing mechanical strength. The pipe joint is made of low-magnetic material, which can effectively reduce leakage magnetic field and avoid heat generation, solving the problem of overheating during transformer operation. The utility model can meet the use conditions of special working conditions such as high mechanical characteristics requirements and large capacity demand of transformers. It is not only conducive to the long-distance transportation of large-capacity transformers in units, but also flexibly and quickly completes the on-site assembly of the mechanical structure and electrical connections of three single-phase transformers. It also effectively solves the problems of mechanical strength and electrical insulation margin of the interphase connection structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0015] Figure 1 This is a front view of the inter-phase connection structure of the three-phase combined transformer according to the first embodiment of the present utility model;

[0016] Figure 2 This is a left side view of the inter-phase connection structure of the three-phase combined transformer according to the first embodiment of the present utility model;

[0017] Figure 3 This is a schematic diagram of the interphase lead connection structure from a top view of the first embodiment of the present utility model;

[0018] Figure 4 Schematic diagram of a metal bellows according to a first embodiment of the present invention, 4a is a front view, 4b is a left view;

[0019] Figure 5 Schematic diagram of the structure of the stacking terminal block of the first embodiment of the present invention, 5a is the existing snap-on terminal block, 5b is the stacking terminal block;

[0020] Among them, 1- pipe joint, 2- metal bellows, 3- fixing plate, 4- plate-shaped wire clamp, 5- low-voltage lead, 6- neutral point lead, 7- stacked terminal, 8- fixing ear, 9- fully threaded stud, 10- second nut, 11- low-voltage copper busbar, 12- neutral point lead connector, 13- L-shaped wire clamp, 14- snap-on terminal. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Example 1

[0022] like Figure 1-5 As shown, a three-phase combined transformer interphase connection structure includes a metal bellows 2 made of stainless steel and a pipe joint 1 made of low magnetic steel fixedly connected to both ends of the metal bellows 2. One end of the pipe joint 1 is fixedly connected to the metal bellows 2 by a flange and bolts, and the other end of the pipe joint 1 is welded to the oil tank outlet of the three single-phase transformers to be connected. In the first embodiment of the present invention, by arranging an adjustable metal bellows 2 between the oil tanks of the three single-phase transformers to be connected, a reliable and flexible fixed connection between the three single-phase transformers is achieved, which facilitates the on-site installation and adjustment of the three-phase combined transformer. One end of the pipe joint 1 connected to the oil tank passes through the oil tank wall and is inserted 10 mm into the oil tank before being welded. After welding, the 10 mm portion extending into the oil tank is cut off, and the welding part is polished to a rounded arc and remove sharp corners and burrs.

[0023] Figure 1 、 Figure 3 It is a partial perspective view of the interior of the pipe joint 1 and the metal bellows 2. Figure 1 、 Figure 3 The leads in the circuit are clamped by a pair of plate-shaped wire clamps 4. Figure 1 、 Figure 3 The L-shaped wire clamp 13 and the plate-shaped wire clamp 4 on the low-voltage side are arranged in a vertical direction. Figure 1 、 Figure 3The L-shaped wire clamp 13 and the plate-shaped wire clamp 4 on the high-voltage side are arranged in a horizontal direction. Taking the low-voltage side as an example, the rectangular fixing plate 3 is fixedly installed on the top of the inner wall of the pipe joint 1 by welding. The fixing plate 3 is provided with a first internal threaded hole, and the two ends of the L-shaped wire clamp 13 are respectively provided with a first through hole and a second through hole. The upper end of the L-shaped wire clamp 13 is screwed into the first internal threaded hole through a bolt through the first through hole to fix the upper end of the L-shaped wire clamp 13 to the fixing plate 3; one end of the plate-shaped wire clamp 4 is provided with a third through hole, and a bolt is passed through the second through hole and the lower end of the L-shaped wire clamp 13. Tighten the nut on the third through hole of the plate-shaped wire clamp 4 to securely mount the upper end of the plate-shaped wire clamp 4 to the lower end of the L-shaped wire clamp 13. Symmetrically with the top end of the upper inner wall of the pipe joint 1, the fixing plate 3, the L-shaped wire clamp 13, and the plate-shaped wire clamp 4 are sequentially secured upward from the bottom end of the lower inner wall of the pipe joint 1. The adjacent ends of a pair of plate-shaped wire clamps 4 are provided with a snap-fit ​​structure. The ends of the pair of plate-shaped wire clamps 4 with the snap-fit ​​structure securely clamp and secure the lead wire (the ends of the pair of plate-shaped wire clamps 4 act like forks to clamp and secure the lead wire).

[0024] Two low-voltage leads 5 pass through the pipe joint 1 and the metal bellows 2 on the low-voltage side, and a neutral-point lead 6 passes through the pipe joint 1 and the metal bellows 2 on the high-voltage side. Both the low-voltage leads 5 and the neutral-point lead 6 are clamped and fixed by a pair of plate-shaped wire clamps 4 located in the pipe joint 1. The end of the low-voltage lead 5 is fixedly connected to the head end of a stacked terminal 7 by crimping, and the head end of the other stacked terminal 7 is fixedly connected to one end of a low-voltage copper busbar 11 by crimping. The other end of the low-voltage copper busbar 11 is fixedly connected to the low-voltage winding in the single-phase transformer, and the stacked ends of the pair of stacked terminals 7 overlap together; the end of the neutral-point lead 6 is fixedly connected to the head end of one stacked terminal 7 by crimping, and the head end of the other stacked terminal 7 is fixedly connected to one end of a neutral-point lead joint 12 by crimping. The other end of the neutral-point lead joint 12 is fixedly connected to the high-voltage winding in the single-phase transformer. The stacking ends of the stacking terminals 7 are provided with fourth through holes. Bolts pass through the fourth through holes and then are fastened by nuts to securely connect the stacking terminals 7 .

[0025] After the three-phase combined transformer is installed in place and combined and connected into one, in order to improve the mechanical strength of the connection of the metal bellows 2, several corresponding fixing ears 8 are evenly welded on the outer peripheral edges of the pipe joint end flange of the pipe joint 1 and the metal bellows end flange of the metal bellows 2, and a full-threaded stud 9 is inserted into a group of fixing ears 8 corresponding to each other on the same horizontal line. On the side of the full-threaded stud 9 close to the metal bellows end flange, a flat washer, a spring washer and a pair of second nuts 10 are installed in sequence from the metal bellows end flange to the outside. On the side of the full-threaded stud 9 close to the pipe joint end flange, a flat washer, a spring washer and a single second nut 10 are installed in sequence from the pipe joint end flange to the outside to achieve the effect of reliable fastening and flexible adjustment. Two-point fixation is performed on the full-threaded stud 9, which not only ensures electrical insulation but also increases mechanical strength.

[0026] In the first embodiment of the present invention, a stacking terminal 7 is used instead of a snap-on terminal 14. Since the snap-on terminal 14 is made of copper rod, which is expensive and takes a long time to manufacture, the stacking terminal 7 is low-cost and has a short manufacturing cycle, greatly facilitating the connection of the internal leads of the pipe joint 1.

[0027] Copper busbars are usually used as leads for low-voltage leads in large-capacity single-phase transformers due to the large current and the need to adjust the DC resistance unbalance rate. However, the copper busbars have poor operability when passing through the pipe joint 1 and the metal bellows 2. Therefore, the present invention uses multiple lead cables instead of copper busbars and utilizes an innovatively designed stacked terminal block 7 to connect the copper busbars in the single-phase transformer. Example 2

[0028] A large-capacity three-phase combined transformer according to a second embodiment of the present invention includes an A-phase transformer, a B-phase transformer, and a C-phase transformer connected in sequence. The three-phase combined transformer inter-phase connection structure described in the first embodiment is applied between the A-phase transformer and the B-phase transformer, and between the B-phase transformer and the C-phase transformer, to form an integrated assembly.

[0029] On the low-voltage side of the transformer, the A-phase low-voltage copper busbar of the A-phase transformer is connected to one end of a low-voltage lead wire 5. The other end of the low-voltage lead wire 5 passes through a pipe joint 1 and a metal bellows 2 to connect to the a-phase low-voltage lead wire of the B-phase transformer. The C-phase low-voltage copper busbar of the C-phase transformer is connected to one end of a low-voltage lead wire 5. The other end of the low-voltage lead wire 5 passes through a pipe joint 1 and a metal bellows 2 to connect to the c-phase low-voltage lead wire of the B-phase transformer. The a-phase low-voltage lead wire of the B-phase transformer is then connected to the b-phase low-voltage lead wire and the c-phase low-voltage lead wire. The low-voltage lead wire 5 is held in place in the pipe joint 1 by an L-shaped wire clamp 13 and a plate-shaped wire clamp 4.

[0030] According to the bushing arrangement, the neutral point lead needs to be clamped in the high-voltage side corrugated pipeline. The high-voltage sides of the A-phase transformer, the B-phase transformer and the C-phase transformer are connected with the neutral point lead 6, which is clamped and fixed in the pipe joint 1 by the L-shaped wire clamp 13 and the plate-shaped wire clamp 4.

[0031] In the second embodiment of the present invention, the neutral point lead current is small, and only a single lead cable is used; the low voltage lead current is large, and the number of lead cables is large, and there are two leads.

[0032] In the embodiments of the present invention, technical features that are not described in detail are all existing technologies or conventional technical means and will not be described in detail here.

[0033] Finally, it should be noted that the above embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any person skilled in the art can modify or easily conceive of changes to the technical solutions described in the above embodiments within the technical scope disclosed by the present invention, or replace some of the technical features therein with equivalents. Such modifications, changes or replacements do not deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A three-phase combined transformer interphase connection structure, comprising a metal bellows (2) and pipe joints (1) fixedly connected to both ends of the metal bellows (2), characterized in that: The pipe joint (1) is made of low-magnetic steel. A plurality of symmetrically arranged fixed plates (3) are welded on the inner wall of the pipe joint (1). One end of the L-shaped wire clamp (13) is fixedly connected to the fixed plate (3). The other end of the L-shaped wire clamp (13) is fixedly connected to one end of the plate-shaped wire clamp (4). The other ends of the adjacent plate-shaped wire clamps (4) are provided with a buckle structure. The pipe joint (1) and the metal bellows (2) are respectively provided with a pipe joint end flange and a metal bellows end flange. The outer edges of the pipe joint end flange and the metal bellows end flange are provided with a plurality of corresponding fixed ears (8). A full-thread stud (9) is inserted into a group of fixed ears (8) on the same horizontal line. Flat washers, spring washers and paired second nuts (10) are sequentially installed on the full-thread stud (9) starting from the metal bellows end flange. Flat washers, spring washers and a single second nut (10) are sequentially installed on the full-thread stud (9) starting from the pipe joint end flange.

2. The inter-phase connection structure of the three-phase combined transformer according to claim 1, characterized in that: Two low-voltage leads (5) pass through the pipe joint (1) and the metal bellows (2) on the low-voltage side, and a neutral point lead (6) passes through the pipe joint (1) and the metal bellows (2) on the high-voltage side. Both the low-voltage lead (5) and the neutral point lead (6) pass through a buckle structure provided by a pair of plate-shaped wire clamps (4) located in the pipe joint (1).

3. The inter-phase connection structure of the three-phase combined transformer according to claim 2, characterized in that: The end of the low-voltage lead (5) is fixedly connected to the head end of a stacked terminal (7) by crimping, and the head end of the other stacked terminal (7) is fixedly connected to one end of the low-voltage copper busbar (11) by crimping. The end of the neutral point lead (6) is fixedly connected to the head end of one stacked terminal (7) by crimping, and the head end of the other stacked terminal (7) is fixedly connected to one end of the neutral point lead connector (12) by crimping. The stacked end of the stacked terminal (7) is provided with a fourth through hole. The stacked ends of a pair of stacked terminal (7) are overlapped together. A fourth bolt passes through the fourth through hole and then fastens the pair of stacked terminal (7) through a fourth nut.

4. The inter-phase connection structure of the three-phase combined transformer according to claim 1, characterized in that: A first internal threaded hole is formed on the fixing plate (3), and a first through hole and a second through hole are formed at both ends of the L-shaped wire clamp (13), and a first bolt passes through the first through hole at the upper end of the L-shaped wire clamp (13) and is screwed into the first internal threaded hole; a third through hole is formed at one end of the plate-shaped wire clamp (4), and a third bolt passes through the second through hole at the lower end of the L-shaped wire clamp (13) and the third through hole of the plate-shaped wire clamp (4), and a threaded end of the third bolt is screwed into a third nut.

5. The inter-phase connection structure of the three-phase combined transformer according to claim 4, characterized in that: The metal bellows (2) is made of stainless steel.

6. A three-phase combined transformer, comprising a single-phase transformer of phase A, a single-phase transformer of phase B and a single-phase transformer of phase C, characterized in that: The A-phase single-phase transformer, the B-phase single-phase transformer and the C-phase single-phase transformer are fixedly connected into one body using the three-phase combined transformer inter-phase connection structure as described in claim 3.

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