distribution transformers

Abstract

The present invention relates to a distribution transformer, comprising a silicon steel core, a low-voltage coil, and a high-voltage coil. The low-voltage coil is wound around the core column of the core, and the high-voltage coil is wound around the outside of the low-voltage coil. The low-voltage coil is wound in a left-hand direction, and the high-voltage coil is wound in a right-hand direction. The tapping section of the high-voltage coil is located on the main airway side. The low-voltage coil is wound using copper foil, the width of the copper foil being greater than the reactance height of the high-voltage coil, and a nylon spacer is provided between the coil and the clamp. The present invention can effectively reduce the radial and axial electromotive forces borne by the coil, reduce the copper consumption of the coil, reduce copper loss, reduce transformer temperature rise, save energy, effectively ensure the fluidity of the transformer oil, improve the heat dissipation effect of the coil, improve the transformer's ability to withstand short circuits, and save wood.

Description

Technical Field

[0001] The invention relates to a distribution transformer and belongs to the field of transformers. Background Art

[0002] With the development of society, the requirements for the power supply quality and reliability of the distribution network are becoming increasingly stringent. Improving the performance of distribution transformers can effectively improve power supply reliability and ensure the safety of power supply equipment. Traditional distribution transformer technology has become stable, but the following defects still exist: 1. Both high- and low-voltage coils are wound with copper wire, which has high copper consumption and high material consumption. The coils are subjected to large axial forces and high coil temperature rise, requiring a large margin in the design. 2. The coils are insulated using a varnishing process. The varnish used is mostly a two-component varnish with volatile diluents, which is often harmful to the human body and pollutes the environment. 3. The coils use a varnishing process to reduce the radial force of the high-voltage coil, but the effect is not significant. 4. The set gap between the low-voltage coil and the core leg is large, and the low-voltage coil is prone to inward collapse due to radial electrodynamic forces. 5. The spacers between the coil and the clamp, as well as the high- and low-voltage lead wire clamps, are made of high-density laminated wood. The large amount of wood used affects the social environment and makes it difficult to form a good dielectric channel, affecting the heat dissipation effect. Summary of the Invention

[0003] In order to overcome the above-mentioned defects of the prior art, the present invention provides a distribution transformer, which can effectively reduce copper consumption, improve the heat dissipation capacity of the coil, reduce the radial force of the coil, save wood, and improve the transformer's ability to withstand short circuits.

[0004] The technical solution for achieving the above-mentioned purpose of the present invention is: a distribution transformer, comprising a silicon steel sheet core, a low-voltage coil and a high-voltage coil, the low-voltage coil being wound on the core column of the core, the high-voltage coil being wound on the outside of the low-voltage coil, the winding direction of the low-voltage coil being opposite to the winding direction of the high-voltage coil, for example, the winding direction of the low-voltage coil is left-handed, the winding direction of the high-voltage coil is right-handed, and the tapping section of the high-voltage coil is located on the main airway side.

[0005] Preferably, the low-voltage coil is wound with copper foil, and the width of the copper foil is greater than the reactance height of the high-voltage coil.

[0006] Preferably, each layer of the low-voltage coil is separated by diamond-shaped dotted paper, and each layer of the high-voltage coil is separated by diamond-shaped dotted paper.

[0007] Preferably, a gap is left between the low-voltage coil and the core of the iron core, and the gap is 1-1.5 mm.

[0008] Preferably, the phases of the distribution transformer are supported and tightened by epoxy resin plates.

[0009] Preferably, clamps are respectively provided on the front and rear sides of the top end of the iron core and the front and rear sides of the bottom end of the iron core, and a pad is provided between the clamp and the coil, and the pad includes a plurality of parallel pad strips, and the spacing between any two adjacent pad strips is the same, and any two adjacent pad strips are connected by a group of connecting rods, each group of connecting rods includes a plurality of parallel connecting rods perpendicular to the pad strips, and any two adjacent groups of connecting rods are staggered, and the length of the two outermost pad strips is smaller than the length of the remaining pad strips, and vertically protruding positioning columns are provided on the upper surface or lower surface of the two outermost pad strips, and the clamp is provided with a positioning hole suitable for the positioning column to be inserted and fixed.

[0010] Preferably, a horizontal high-voltage lead wire clamp is provided on the upper clamp on the high-voltage side of the distribution transformer, and the high-voltage lead wire clamp is composed of a first clamp and a second clamp superimposed and fixed up and down, a first notch recessed to the left is provided on the right side of the first clamp, a second notch recessed to the right is provided on the left side of the second clamp, a third notch recessed backward is provided on the front side of the second clamp, and the third notch is located on the right side of the second notch, the first notch, the second notch and the third notch are superimposed up and down to form two high-voltage lead wire holes, a horizontal hook protruding backward is respectively provided on the rear side of the first clamp and the second frame plate, the two hooks are symmetrically arranged on the left and the hook ends are opposite, and a hanging groove suitable for the two hooks to be fixedly hung is provided on the clamp.

[0011] Preferably, a low-voltage lead wire clamp is provided on the upper clamping piece on the low-voltage side of the distribution transformer, and the low-voltage lead wire clamp includes two wire clamping blocks and a wire clamping plate. The wire clamping block is stepped, and the length of its first step is greater than the length of its second step. The first step is provided with a first through hole in the form of an elongated strip that passes through the block, and the second step is provided with a second through hole in the form of a circular strip that passes through the block. The parts of the wire clamping block other than the first through hole and the second through hole are hollowed out, and the two wire clamping blocks are fitted together front and back, and the first step and the second step of one wire clamping block are respectively aligned with the second step of the other wire clamping block. The first step and the second step are tightly attached to each other, and a vertical gap is formed between the first step and the second step of the two wire clamp blocks. The wire clamp plate is clamped in the gap, and the first through hole and the second through hole on one wire clamp block are respectively connected with the second through hole and the first through hole of the other wire clamp block to form two wire clamp mounting holes. The upper clamp on the low-voltage side is provided with a clamp mounting hole that matches the two wire clamp mounting holes. The low-voltage lead wire clamp is bolted to the upper clamp on the low-voltage side. The wire clamp mounting hole and the clamp mounting hole serve as connecting holes for bolt connection, and the wire clamp plate is provided with a low-voltage lead wire hole that passes through the plate surface.

[0012] Preferably, vertical top plates are respectively provided on the outer sides of the A and C phase coils of the distribution transformer, the left and right ends of the two upper clamps are respectively fixedly connected by an upper cross beam, the left and right ends of the two lower clamps are respectively fixedly connected by a lower cross beam, the top and bottom ends of the top plate are respectively fixedly connected to the upper cross beam and the lower cross beam, laminated cardboard is provided between the top plate and the coil, phenolic paper tubes are respectively provided on the left and right sides of the iron yoke at the upper and lower ends of the iron core, the front and rear ends of the phenolic paper tube are respectively fixedly connected to the clamps located on the front and rear sides of the iron core, and the tube body of the phenolic paper tube is pressed against the side of the iron yoke.

[0013] Preferably, a pressure plate is provided on the upper end surface of the iron yoke, and the front and rear ends of the pressure plate are respectively fixedly connected to the two upper clamps. The pressure plate includes a horizontal plate and a vertical plate. The side end of the horizontal plate is fixedly connected to the bottom end of the vertical plate, or the horizontal plate and the vertical plate adopt an integrated structure. The horizontal plate is pressed against the upper end surface of the iron yoke, and the vertical plate is wedge-shaped with a gradually changing height from front to back. The bottom ends of the two lower clamps are provided with pads.

[0014] The beneficial effects of the present invention are:

[0015] 1. The high-voltage coil of the present invention adopts a right-hand winding direction and the tapping section is located on the main air channel side, which changes the traditional method of reducing the radial force of the high-voltage coil by means of paint dipping and other means. By adjusting the structure of the high-voltage coil itself, its radial force distribution is changed, thereby effectively reducing the radial force borne by the high-voltage coil.

[0016] 2. The low-voltage coil of the present invention is wound with copper foil, and the width of the copper foil is greater than the reactance height of the high-voltage coil. This can not only reduce copper material consumption, reduce copper loss, reduce transformer temperature rise, and save energy, but also reduce the axial electric force exerted on the coil, change the force distribution of the overall axial electric force of the coil, so that the axial electric force of the low-voltage coil is stretched outward and the axial electric force of the high-voltage coil is compressed inward, thereby improving the coil's axial electric force bearing capacity and improving the overall performance of the coil.

[0017] 3. The coil of the present invention does not need to be treated with varnish for insulation and does not use volatile chemical paint that is harmful to the human body and the environment, which can effectively ensure the safety of workers and protect the environment.

[0018] 4. The low-voltage coil of the present invention is sheathed with a small gap between the core and the core, which can effectively reduce the amount of inward collapse and contraction of the low-voltage coil due to radial electromotive force.

[0019] 5. The present invention uses a nylon pad with a unique structure as a pressure plate between the coil and the clamp. Compared with the traditional use of laminated wood as a pressure plate, it can effectively ensure the fluidity of transformer oil, improve the heat dissipation effect of the coil, improve the transformer's ability to withstand short circuits, and save wood.

[0020] 6. The unique structural design and material of the high-voltage lead wire clamp and the low-voltage lead wire clamp of the present invention not only facilitate their own installation and fixation of the lead wires, but also save wood.

[0021] 7. The iron core, clamps, top plate, crossbeam, pressure plate and phenolic paper tube of the present invention together constitute a rigid frame of the coil, which can effectively limit the outward bending deformation of the high-voltage coil caused by the radial electromotive force and the upward or downward deformation of the high and low voltage coils caused by the axial electromotive force. The present invention greatly improves the ability of the transformer to withstand short circuits by increasing its overall strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0023] Figure 2 1 is a schematic diagram of the top view of the cushion block of the present invention;

[0024] Figure 3 is a schematic diagram of the three-dimensional structure of the first splint of the present invention;

[0025] Figure 4 is a schematic diagram of the three-dimensional structure of the second splint of the present invention;

[0026] Figure 5 It is a schematic diagram of the three-dimensional structure of the wire clamp block of the present invention;

[0027] Figure 6 It is a front view of the present invention;

[0028] Figure 7 is a side view of the present invention;

[0029] Figure 8 It is a top view of the present invention. DETAILED DESCRIPTION

[0030] The present invention discloses a distribution transformer, comprising a silicon steel sheet core, a low-voltage coil and a high-voltage coil. The low-voltage coil is wound on the core column of the core, and the high-voltage coil is wound on the outside of the low-voltage coil. The winding direction of the low-voltage coil is left-handed, and the winding direction of the high-voltage coil is right-handed. The tapping section of the high-voltage coil is located on the main airway side. By adjusting the structure of the high-voltage coil itself, the radial force distribution thereof is changed, thereby effectively reducing the radial force borne by the high-voltage coil.

[0031] The low-voltage coil is preferably wound with copper foil, which can reduce copper material consumption, reduce copper loss, reduce transformer temperature rise, and save energy.

[0032] The width of the copper foil is preferably greater than the reactance height of the high-voltage coil. Combined with the reverse winding method of the high and low voltage coils, the axial electric force exerted on the coil can be significantly reduced, and the force distribution of the axial electric force of the entire coil can be changed, so that the axial electric force of the low-voltage coil is stretched outward and the axial electric force of the high-voltage coil is compressed inward, thereby improving the axial electric force bearing capacity of the coil and improving the overall performance of the coil.

[0033] The layers of the low-voltage coil are preferably separated by diamond-shaped adhesive paper to achieve bonding and insulation. The layers of the high-voltage coil are preferably separated by diamond-shaped adhesive paper to achieve insulation. Compared with the traditional method of using varnish for insulation treatment, no volatile chemical paint that is harmful to the human body and the environment is used, which can effectively ensure the safety of the staff and protect the environment. Since the copper foil and the diamond-shaped adhesive paper fit well, evenly and without gaps, they can form high integrity and insulation performance after curing and bonding, and can significantly reduce vibration and noise.

[0034] Preferably, only a tiny assembly gap is left between the low-voltage coil and the core column of the iron core. The gap is preferably 1-1.5mm, such as 1mm, 1.2mm or 1.5mm. The low-voltage coil is effectively supported by a silicon steel sheet core, and a continuous support beam structure is formed inside the low-voltage coil. A small gap is used between the low-voltage coil and the core column of the iron core, which can effectively reduce the amount of inward collapse and shrinkage of the low-voltage coil due to radial electromotive force.

[0035] A diamond-shaped dotted paper pad can be set between the low-voltage coil and the core column of the iron core to fill the gap between the low-voltage coil and the core column of the iron core. The low-voltage coil, the diamond-shaped dotted paper pad and the iron core can be tightly fitted so that the diamond-shaped dotted paper pad has a certain compressive deformation, but the low-voltage coil and the iron core do not produce deformation, thereby better restraining the collapse, contraction and vibration caused by radial electromotive force without damaging the coil and the iron core.

[0036] The phases of the distribution transformer are preferably supported and tightened with epoxy resin plates to improve structural stability.

[0037] See also Figures 1 to 8 The front and rear sides of the top of the iron core and the front and rear sides of the bottom of the iron core are respectively provided with clamps 1, the left and right ends of the two upper clamps are respectively fixedly connected by upper cross beams 2 (such as bolt connections), and the left and right ends of the two lower clamps are respectively fixedly connected by lower cross beams 3 (such as bolt connections), and the upper clamp and the lower clamp on the same side of the iron core are fixedly connected by vertical pull rods 4 (such as bolt connections).

[0038] A pad 5 is provided between the clamp and the coil, and the pad includes several parallel pad strips 6. The spacing between any two adjacent pad strips is the same, and any two adjacent pad strips are connected by a group of connecting rods 7. Each group of connecting rods includes several connecting rods that are parallel and perpendicular to the pad strips. The spacing between any two adjacent connecting rods is the same, and any two adjacent groups of connecting rods are staggered. Preferably, any one link in any group of links has the same vertical spacing as the two links adjacent to it in an adjacent group of links, and a unique connection structure between a plurality of pad blocks and a plurality of groups of links forms a plurality of through holes on the pad block that are regularly staggered and pass through the block body up and down, and the lengths of the two pad blocks located on the outermost side are smaller than the lengths of the remaining pad blocks, and the lengths of the remaining pad blocks except the two pad blocks located on the outermost side are the same, and the lengths of the two pad blocks located on the outermost side are the same, and vertically protruding positioning columns 8 are provided on the upper or lower surfaces of the two pad blocks located on the outermost side, and a positioning hole suitable for inserting and fixing the positioning column is provided on the clamp, and the pad is installed between the clamp and the coil by inserting the positioning column into the matching positioning hole on the clamp.

[0039] The pad is preferably a nylon pad. Compared with the traditional pad made of laminated wood, the unique structure of the pad (through holes with regular staggered distribution) and material selection can effectively ensure the fluidity of transformer oil, improve the heat dissipation effect of the coil, improve the transformer's ability to withstand short circuits, and save wood.

[0040] The thickness of the connecting rod (the dimension in the vertical direction) is preferably smaller than the thickness of the pad bar, and its center height in the vertical direction is preferably the same as the center height of the pad bar in the vertical direction. Under the support of the pad bar, there are gaps above and below the connecting rod to allow the flow of medium. Combined with the mesh structure formed by the pad bar and the connecting rod, it can significantly improve the circulation effect of transformer oil, improve the heat dissipation capacity, and improve the heat dissipation effect. Compared with the existing wooden pads, it significantly reduces the impact of the setting of pads on the heat dissipation effect of the corresponding area.

[0041] A horizontal high-voltage lead wire clamp 9 is provided on the upper clamping piece on the high-voltage side of the distribution transformer for fixing the high-voltage lead. The high-voltage lead wire clamp is preferably composed of a first clamping plate 10 and a second clamping plate 11 that are overlapped and fixed up and down. A first notch 12 that is recessed to the left is provided on the right side of the first clamping plate, a second notch 13 that is recessed to the right is provided on the left side of the second clamping plate, and a third notch 14 that is recessed backward is provided on the front side of the second clamping plate. The third notch is located on the right side of the second notch. The position of the first notch on the first clamping plate corresponds to the position of the second notch and the third notch on the second clamping plate. The first clamping plate is located above the second clamping plate. The first notch, the second notch and the third notch are overlapped up and down to form two high-voltage lead wire holes for The high-voltage lead passes through, and a horizontal hook 15 protruding backward is provided on the rear side of each of the first clamping plate and the second frame plate. The two hooks are symmetrically arranged on the left and right (symmetrical with the center line of the left and right directions of the high-voltage wire clamp) and the hook ends are opposite. The clamp is provided with a hanging groove suitable for horizontal fixed hanging of the two hooks. The high-voltage lead wire clamp is hung in the hanging groove through the two hooks. The high-voltage wire clamp is preferably made of nylon. The first clamping plate and the second clamping plate are both provided with a number of connection holes 16 that pass through the plate surface up and down. The positions of the several connection holes on the first clamping plate correspond one to one with the positions of the several connection holes on the second clamping plate. The first clamping plate and the second clamping plate can be fixedly connected by bolts passing through the corresponding connection holes and nuts screwed on the ends of the bolts.

[0042] A low-voltage lead wire clamp is provided on the upper clamping piece on the low-voltage side of the distribution transformer for fixing the low-voltage lead. The low-voltage lead wire clamp preferably includes two wire clamping blocks 17 and a wire clamping plate 18. The wire clamping block is stepped, and the length of its first step 19 is greater than the length of its second step 20. The first step is provided with a first through hole 21 in the form of an elongated strip that passes through the block, and the second step is provided with a second through hole 22 in the form of a circle that passes through the block. The parts of the wire clamping block other than the first through hole and the second through hole are hollowed out. The two wire clamping blocks are fitted together front and back, and the first step and the second step of one wire clamping block are respectively tightly attached to the second step and the first step of the other wire clamping block. The first step of the two wire clamping blocks A vertical gap is formed between the step and the second step, and the wire clamp is clamped in the gap. The first through hole and the second through hole on one wire clamp block are respectively connected to the second through hole and the first through hole of the other wire clamp block to form two wire clamp mounting holes. The upper clamp on the low-voltage side is provided with a clamp mounting hole that matches the two wire clamp mounting holes. The low-voltage lead wire clamp and the upper clamp on the low-voltage side can be connected by bolts. The wire clamp mounting hole and the clamp mounting hole serve as connecting holes for bolt connection. The wire clamp is provided with a low-voltage lead wire hole 23 that passes through the board surface for the low-voltage lead to pass through. The part of the wire clamp located above the wire clamp block can be bent outward, and the low-voltage lead wire clamp is preferably made of nylon.

[0043] The unique structural design and material of the high-voltage lead wire clamp and the low-voltage lead wire clamp not only facilitate their own installation and fixation of the leads, but also save wood (compared to the traditional technology using laminated wood as the material).

[0044] The outer sides of the A and C phase coils of the distribution transformer can be respectively provided with vertical top plates 24. The top and bottom ends of the top plates are respectively fixedly connected (such as bolted) to the upper and lower crossbeams on the same side. The top plates press the coils adjacent to them. Laminated cardboard is provided between the top plates and the coils to ensure insulation strength. Phenolic paper tubes 25 can be respectively provided on the left and right sides of the iron yokes at the upper and lower ends of the iron core. The front and rear ends of the phenolic paper tubes are respectively fixedly connected (such as bolted) to the clamps located on the front and rear sides of the iron core corresponding to their positions. The tube body of the phenolic paper tube is pressed against the side of the iron yoke to limit the lateral displacement of the core column of the iron core. A pressure plate 26 may be provided on the upper end surface of the iron yoke, with the front and rear ends of the pressure plate fixedly connected (e.g., bolted) to the two upper clamps, and the pressure plate is preferably installed in the middle of the upper clamp, preferably in two pieces, and the pressure plate includes a horizontal plate and a vertical plate, with the side ends of the horizontal plate fixedly connected to the bottom ends of the vertical plates, or the horizontal plate and the vertical plate are of an integrated structure (e.g., formed by bending steel plates), the horizontal plate is pressed against the upper end surface of the iron yoke, and the vertical plate is wedge-shaped with a gradually changing height from front to back to improve the strength of the pressure plate, the pressure plate can not only press the iron yoke vertically downward, but also prevent the middle part of the upper clamp from being deformed by the fastening protrusion of the vertical pull rod. When installing the pressure plate, first fix the end facing the high-pressure side to the upper clamp on the high-pressure side, then, using the fixing bolts on the high-pressure side as a reference, tighten it toward the low-pressure side, and then fix the end facing the low-pressure side to the upper clamp on the low-pressure side. The bottom ends of the two lower clamps may be provided with feet 27 for support.

[0045] The iron core, the clamp, the top plate, the crossbeam, the pressure plate and the phenolic paper tube together constitute a rigid frame of the coil, which can effectively limit the outward bending deformation of the high-voltage coil caused by the radial electromotive force and the upward or downward deformation of the high and low voltage coils caused by the axial electromotive force.

[0046] The present invention can greatly improve the ability of the transformer to withstand short circuits by improving the overall strength of the transformer.

[0047] The present invention can be mainly used as an oil-immersed transformer.

[0048] The assembly method of the present invention is as follows: a low-voltage coil is wound with copper foil, the low-voltage coil adopts a left-hand winding direction, and each layer of the low-voltage coil is separated by a diamond-shaped glue paper. After the low-voltage coil is wound, it is dried and solidified. Then, a high-voltage coil is wound on the outside of the low-voltage coil, the high-voltage coil adopts a right-hand winding direction, and each layer of the high-voltage coil is separated by a diamond-shaped glue paper. The wound coil is sheathed on the core column of the iron core, and a gap of 1-1.5 mm is left between the low-voltage coil and the core column of the iron core. After the coil is sheathed, epoxy resin plates are used to support the phases, and the A, The outer side of the C-phase coil is pressed by a top plate, and laminated cardboard is placed between the top plate and the coil. The top plate is fixedly connected to the upper and lower clamps through a crossbeam. The upper end face of the iron yoke is pressed by a pressing plate, and the pressing plate is fixedly connected to the upper clamp. The left and right sides of the iron yoke at the upper and lower ends of the iron core are pressed by phenolic paper tubes, and the phenolic paper tubes are fixedly connected to the clamps at the corresponding positions. Nylon pads are placed between the coil and the clamps. The upper and lower clamps on the same side are fixedly connected and pressed by vertical pull rods, thereby forming a stable rigid structure. High and low voltage lead wire clamps are installed on the upper clamp.

Claims

1. A distribution transformer comprising a silicon steel core, a low voltage coil and a high voltage coil, characterized in that The low-voltage coil is wound on the core column of the iron core, and the high-voltage coil is wound on the outside of the low-voltage coil. The winding direction of the low-voltage coil is left-handed, and the winding direction of the high-voltage coil is right-handed. The branch section of the high-voltage coil is located on the main airway side. The low-voltage coil is wound with copper foil, and the width of the copper foil is greater than the reactance height of the high-voltage coil. A gap is left between the low-voltage coil and the core column of the iron core. The gap between the low-voltage coil and the core column of the iron core is 1-1.5mm. The front and rear sides of the top of the iron core and the front and rear sides of the bottom of the iron core are respectively provided with clamps. The clamps located on the front and rear sides of the top of the iron core are upper clamps, including the upper clamp on the high-voltage side and the upper clamp on the low-voltage side. The clamps located on the front and rear sides of the bottom of the iron core are lower clamps, including the lower clamp on the high-voltage side and the lower clamp on the low-voltage side. A pad is provided between the clamp and the coil, and the pad includes several The cam is secured to a position about 100 meters and has a plurality of holes formed on the top and bottom of the cam, the holes being configured to fit the respective positions of the cam and the second position.

2. The distribution transformer according to claim 1, characterized in that Each layer of the low-voltage coil is separated by diamond-shaped dotted paper.

3. The distribution transformer according to claim 1, characterized in that The layers of the high-voltage coil are separated by diamond-shaped dotted paper.

4. The distribution transformer according to claim 1, characterized in that The spacing between any two adjacent pad blocks is the same, and any two adjacent pad blocks are connected by a group of connecting rods. Each group of connecting rods includes several connecting rods that are parallel and perpendicular to the pad blocks, and any two adjacent groups of connecting rods are staggered.

5. The distribution transformer according to claim 1, characterized in that The phases of the distribution transformer are supported and tightened by epoxy resin plates.

6. The distribution transformer according to claim 1, 2, 3, 4 or 5, characterized in that The lengths of the two outermost spacer strips are shorter than the lengths of the remaining spacer strips.

7. The distribution transformer according to claim 6, characterized in that A low-voltage lead wire clamp is provided on the upper clamping piece on the low-voltage side, and the low-voltage lead wire clamp includes two wire clamping blocks and a wire clamping plate. The wire clamping block is stepped, and the length of its first step is greater than the length of its second step. The first step is provided with a first through hole in the form of an elongated strip that passes through the block, and the second step is provided with a second through hole in the form of a circular strip that passes through the block. The parts other than the first through hole and the second through hole on the wire clamping block are hollowed out, and the two wire clamping blocks are fitted together front and back, and the first step and the second step of one wire clamping block are respectively aligned with the second step and the first step of the other wire clamping block Tightly attached, a vertical gap is formed between the first step and the second step of the two wire clamp blocks, the wire clamp plate is clamped in the gap, the first through hole and the second through hole on one wire clamp block are respectively connected with the second through hole and the first through hole of the other wire clamp block to form two wire clamp mounting holes, the upper clamp on the low-voltage side is provided with a clamp mounting hole that matches the two wire clamp mounting holes, the low-voltage lead wire clamp is bolted to the upper clamp on the low-voltage side, the wire clamp mounting hole and the clamp mounting hole serve as connecting holes for bolt connection, and the wire clamp plate is provided with a low-voltage lead wire hole that passes through the plate surface.

8. The distribution transformer according to claim 7, characterized in that A vertical top plate is provided on the outside of the A and C phase coils of the distribution transformer, respectively. The left and right ends of the two upper clamps are fixedly connected by an upper crossbeam, respectively. The left and right ends of the two lower clamps are fixedly connected by a lower crossbeam, respectively. The top and bottom ends of the top plate are fixedly connected to the upper crossbeam and the lower crossbeam, respectively. Laminated cardboard is provided between the top plate and the coil. Phenolic paper tubes are provided on the left and right sides of the iron yokes at the upper and lower ends of the iron core, respectively. The front and rear ends of the phenolic paper tubes are fixedly connected to the clamps located on the front and rear sides of the iron core, respectively. The tube body of the phenolic paper tube is pressed tightly against the side of the iron yoke.

9. The distribution transformer according to claim 8, characterized in that A pressure plate is provided on the upper end surface of the iron yoke, and the front and rear ends of the pressure plate are respectively fixedly connected to the two upper clamps. The pressure plate includes a horizontal plate and a vertical plate. The side end of the horizontal plate is fixedly connected to the bottom end of the vertical plate, or the horizontal plate and the vertical plate adopt an integrated structure. The horizontal plate is pressed tightly on the upper end surface of the iron yoke, and the vertical plate is wedge-shaped with a gradually changing height from front to back. The bottom ends of the two lower clamps are provided with pads.

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