Transformer

Abstract

The utility model relates to the technical field of power equipment, in particular to a transformer. The transformer comprises an iron core, a clamping piece and a cushion block, an iron core column of the iron core is sleeved with at least two sets of coils at intervals from inside to outside, the clamping piece is clamped on the iron core, the clamping piece is provided with a structure used for being matched with the cushion block in an abutting mode so that the cushion block can apply abutting force to the ends of the sets of coils in the axial direction of the coils, and a radial limiting block is arranged between every two adjacent sets of coils. The radial limiting blocks abut against the inner and outer opposite side faces of the two adjacent sets of coils so as to limit the radial distance between the two adjacent sets of coils. And the radial limiting blocks are matched with the cushion blocks to limit each group of coils, so that the limiting and fixing effects on the coils are enhanced, the relative positions of two adjacent groups of high-voltage and low-voltage coils during sudden short circuit are ensured, radial displacement is not easy to occur, and the electrical performance of the transformer is prevented from being influenced.

Description

TECHNICAL FIELD

[0001] The utility model relates to power equipment technical field, concretely relates to transformer. BACKGROUND

[0002] 35kV dry type grounding transformer is one of the important equipment indispensable in power grid system, and the safe reliability of grounding transformer operation determines the normal operation of power grid. The basic structure of grounding transformer can be seen from the grounding transformer disclosed in the Chinese utility model patent with the authorized announcement number CN205264464U, the grounding transformer is a three-phase transformer, the iron core has three iron core columns, and low-voltage coils and high-voltage coils are coaxially installed on each iron core column. During actual operation of the grounding transformer, when low-voltage short circuit or high-voltage neutral point grounding short circuit fault occurs, the short circuit current will impact the grounding transformer, if the transformer has insufficient short circuit resistance and fails, not only the power supply quality of the overall power grid will be directly affected, but also regional power failure may occur, therefore, the grounding transformer is required to have high short circuit fault resistance.

[0003] The short circuit resistance of grounding transformer includes dynamic stability during short circuit, and the dynamic stability reflects the short circuit electric power resistance of grounding transformer, and the short circuit resistance of grounding transformer is closely related to the short circuit current flowing in the winding coil during short circuit, when sudden short circuit fault occurs, the short circuit current is dozens of times higher than that in the rated operation state, the huge short circuit current can interact with the leakage magnetic field, generate hundreds of times short circuit electric power, and cause the winding coil to be twisted and deformed.

[0004] The basic structure of traditional transformer can be seen from the transformer disclosed in the Chinese utility model patent with the authorized announcement number CN220691847U, the middle-voltage coil, low-voltage coil and high-voltage coil are sleeved on the iron core, the iron core includes iron core columns and iron yokes, the coils are sleeved on the corresponding iron core columns, the coils are sequentially and spacedly arranged from inside to outside, the inside coil is closer to the iron core column than the outside coil, the inside-outside direction is consistent with the radial direction of the coil and perpendicular to the axial direction of the coil; the upper iron yokes on both sides of the iron core are clamped by upper clamping pieces and fixed by screws, and the lower iron yokes on both sides are clamped by lower clamping pieces and fixed by screws; a plurality of insulating pads are arranged between each coil and the upper clamping piece, and a plurality of insulating pads are also arranged between each coil and the lower clamping piece; a plurality of support reinforcing plates are arranged on the upper clamping piece and the lower clamping piece respectively, for supporting and fixing the insulating pads, the support reinforcing plates of the upper clamping piece are used for pressing and fixing the insulating pads by pressing nails, so that the upper insulating pads press the upper end of the coil, the lower end of the coil is pressed on the lower insulating pads, and each coil is clamped and fixed by the upper and lower insulating pads, so as to maintain the relative position of each coil.

[0005] For grounding transformer, in practical application, high voltage neutral point connects arc suppression coil or small resistance, in order to reduce the influence of zero sequence impedance on the performance of matching device, the smaller the zero sequence impedance of grounding transformer is, the better, and when zero sequence short circuit occurs, the smaller the zero sequence impedance is, the greater the zero sequence short circuit current is, the zero sequence impedance of grounding transformer influences the current output size of neutral point when grounding fault operates, the short circuit impedance of grounding transformer is smaller than that of conventional power transformer, correspondingly, the short circuit current is also greater than that of conventional transformer, the electric power that the coil of grounding transformer bears is relatively large, which requires that grounding transformer has stronger short circuit resistance performance.The conventional coil fixing structure that adopts press nail and cooperates with pad to compress each coil end portion, the relative position of each coil in the radial direction is fixed by the compression force of pad and coil end portion, and the fixing effect is not reliable enough, and when the electric power that the coil bears is relatively large, radial displacement and eccentricity are prone to occur, which adversely affects the performance of transformer, and may cause the distance between adjacent two groups of coils to be small and cause insulation risk. Practical new type content

[0006] The utility model discloses a transformer, to solve the structure of the current transformer through pad compression each coil end portion to keep the relative position of each coil is not reliable enough and is easy to occur coil radial displacement when electric power is relatively large and influences electrical performance problem.

[0007] The technical scheme of the transformer of the utility model is:

[0008] The transformer includes a core, a clamp and a pad, at least two groups of coils are arranged on the core column of the core from inside to outside at intervals, the clamp is clamped on the core, and a structure for cooperating with the pad to press from above is arranged on the clamp to make the pad apply a pressing force to each group of coil ends along the axial direction of the coil, and a radial limiting block is arranged between the two adjacent groups of coils, and the radial limiting block abuts against the opposite side surfaces of the two adjacent groups of coils to limit the distance between the two adjacent groups of coils in the radial direction.

[0009] Advantages: the utility model improves the transformer in the prior art, each group of coils is limited by the cooperation of the radial limiting block and the pad, the limiting and fixing effect of the coil is enhanced, the pad applies a pressing force to the coil end under the pressing action of the clamp along the axial direction of the coil, thereby limiting each group of coils in the axial direction, the radial limiting block is located between the two adjacent groups of coils and abuts against the opposite side surfaces of the two adjacent groups of coils, the opposite side surfaces of the two adjacent groups of coils are opposite surfaces in the radial direction of the coil, the radial direction of the coil is perpendicular to the axial direction, and the radial limiting block can limit the distance between the two adjacent groups of coils in the radial direction by being supported between the two groups of coils; the limiting is reliable, the relative position of the two adjacent groups of high-voltage and low-voltage coils is guaranteed when a sudden short circuit occurs, radial displacement is not prone to occur, and the electrical performance of the transformer is not affected.

[0010] Further, a limiting groove is arranged on the pad, and the radial limiting block has a part adapted to extend into the limiting groove.

[0011] Further, an insulating cylinder is arranged between the two adjacent groups of coils, the axial length of the insulating cylinder is greater than the axial length of the coil, the radial limiting block is provided with a slot for inserting the end of the insulating cylinder, and the slot extends to the part of the radial limiting block extending into the limiting groove.

[0012] Further, an insulating cylinder is arranged between the two adjacent groups of coils, the radial limiting block is provided with a slot for inserting the end of the insulating cylinder, and the cushion block is provided with a limiting structure for limiting the radial limiting block.

[0013] Further, the side of the radial limiting block abutting against the coil is a limiting surface, and the limiting surface is matched with the shape of the side of the coil.

[0014] Further, the radial limiting block is an elastic block, and the radial limiting block is elastically deformed when abutting against the coil.

[0015] Further, an elastic pad is arranged between the cushion block and the end of the coil, the elastic pad abuts against the end of the coil, and the cushion block applies a pressing force to the coil through the elastic pad.

[0016] Further, the transformer is a grounding transformer, the core column is sequentially sleeved with a low-voltage coil, a high-voltage inner coil and a high-voltage outer coil from inside to outside, the low-voltage coil, the high-voltage inner coil and the high-voltage outer coil respectively form a group of coils, the radial limiting block is arranged between the low-voltage coil and the high-voltage inner coil and between the high-voltage inner coil and the high-voltage outer coil, and the radial limiting block abuts against the side surface of the end of the coil.

[0017] Further, an inner lining is arranged between the coil located at the innermost side and the core column, and the inner lining comprises an elastic buffering structure.

[0018] Further, the outgoing end of the coil is welded with a cable, the cable serves as the outgoing wire of the coil, an insulating coating layer is fixedly cast outside the coil, and the welding part of the coil and the cable is sealed in the insulating coating layer. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 it is the transverse section view of the transformer of the embodiment of the utility model;

[0020] Figure 2 it is the longitudinal section view of the transformer of the embodiment of the utility model;

[0021] Figure 3 it is the structure schematic view of the cushion block in Figure 1 ;

[0022] Figure 4 it is the installation structure schematic view of the low-voltage coil and the core of the transformer of the embodiment of the utility model;

[0023] Figure 5 it is the structure schematic view of the cushion block in Figure 2The schematic view of the mounting structure of the lead copper bar of the low-voltage coil in the transformer;

[0024] Figure 6 The top view of the high-voltage inner coil and the cable of the transformer of the embodiment of the utility model;

[0025] Figure 7 The schematic view of the connection position of the high-voltage inner coil and the cable of the transformer of the embodiment of the utility model.

[0026] In the figure: 10, iron core; 11, upper yoke; 21, low-voltage coil; 22, high-voltage inner coil; 23, high-voltage outer coil; 24, inner insulation cylinder; 25, outer insulation cylinder; 30, lower clamp; 31, press nail; 32, cushion block; 33, elastic pad; 34, inner radial limiting block; 35, outer radial limiting block; 40, upper clamp; 41, lead support; 42, insulator; 43, inner lead copper bar; 44, outer lead copper bar; 50, cable; 60, glass silk cloth plate; 61, silicon rubber support strip. DETAILED DESCRIPTION

[0027] The basic concept of the utility model is to set radial limiting blocks between the coils of the transformer to cooperate with the cushion blocks to limit each group of coils, enhance the limiting and fixing effect of the coils, and ensure the relative position of the adjacent two groups of high and low voltage coils when a sudden short circuit occurs, so that the radial displacement is not easy to occur.

[0028] The embodiment of the transformer of the utility model:

[0029] As shown in Figure 1 , Figure 2 , Figure 3 The transformer includes an iron core 10, a clamp, a cushion block 32 and a coil. The iron core 10 includes an iron core column and an iron yoke. A plurality of groups of coils are arranged on the iron core column of the iron core 10 from inside to outside in a spaced manner. The clamp is clamped on the iron yoke of the iron core 10. The clamp is provided with a structure for cooperating with the cushion block 32 to press from above so as to make the cushion block 32 apply a pressing force to each group of coil ends along the axial direction of the coil. Radial limiting blocks are arranged between the adjacent two groups of coils. The radial limiting blocks abut against the opposite sides of the adjacent two groups of coils to limit the radial spacing of the adjacent two groups of coils. The cushion block 32 limits each group of coils in the axial direction. The radial limiting blocks are supported between the two groups of coils to limit the radial spacing of the adjacent two groups of coils, form radial limitation of the coils, limit each group of coils by the cooperation of the radial limiting blocks and the cushion block 32, enhance the limiting and fixing effect of the coils, and ensure the relative position of the adjacent two groups of high and low voltage coils 21 when a sudden short circuit of the transformer occurs, so that the radial displacement is not easy to occur, and the electrical performance of the transformer is avoided from being affected.

[0030] The transformer is a three-phase transformer, the iron core 10 has three iron core columns arranged side by side with left and right spacing, the iron core columns are vertically arranged, a coil is sleeved on each iron core column, and each coil is provided with a gasket 32 and a radial limiting block. The coil is arranged around the iron core column, one side of the coil close to the iron core column is an inner side, and the side away from the iron core column is an outer side, the axial direction of the coil is consistent with the axial direction of the iron core column, the radial direction of the coil is perpendicular to the axial direction of the coil, and the axial direction of the coil is the up-down direction. The iron core 10 is fixed with clamping pieces at the upper end and the lower end, the upper clamping piece is an upper clamping piece 40, and the lower clamping piece is a lower clamping piece 30. The upper clamping piece 40 clamps the upper yoke of the iron core 10, and the lower clamping piece 30 clamps the lower yoke of the iron core 10. The lower clamping piece 30 is fixed on the corresponding fixed base. The opposite sides of the two adjacent groups of coils, namely the opposite sides in the radial direction of the coil. The upper end and the lower end of the coil are provided with a gasket 32 and a radial limiting block, and the gaskets 32 on the same side of the coil are arranged in multiple numbers and are uniformly distributed around the iron core column. In this embodiment, the coil winding corresponding to each iron core column is provided with four gaskets 32, and a radial limiting block is arranged at each gasket 32. Figure 1 The installation structure of one gasket 32 is shown, and the structures of the other gaskets are the same.

[0031] The transformer is a 35kV grounding transformer, the iron core column is sequentially sleeved with a low-voltage coil 21, a high-voltage inner coil 22 and a high-voltage outer coil 23 from the inside to the outside, the low-voltage coil 21, the high-voltage inner coil 22 and the high-voltage outer coil 23 respectively constitute a group of coils, radial limiting blocks are arranged between the low-voltage coil 21 and the high-voltage inner coil 22 and between the high-voltage inner coil 22 and the high-voltage outer coil 23, and the radial limiting blocks abut against the side surfaces of the end portions of the coils. The radial limiting block between the low-voltage coil 21 and the high-voltage inner coil 22 is an inner radial limiting block 34, and the radial limiting block between the high-voltage inner coil 22 and the high-voltage outer coil 23 is an outer radial limiting block 35. The spacing between the low-voltage coil 21 and the high-voltage inner coil 22 is greater than the spacing between the high-voltage inner coil 22 and the high-voltage outer coil 23, and accordingly, the axial dimension and the radial dimension of the inner radial limiting block 34 are greater than the axial dimension and the radial dimension of the outer radial limiting block 35. The inner side surface of the inner radial limiting block 34 abuts against the outer side surface of the end portion of the low-voltage coil 21, and the outer side surface of the inner radial limiting block 34 abuts against the inner side surface of the end portion of the high-voltage inner coil 22. The inner side surface of the outer radial limiting block 35 abuts against the outer side surface of the end portion of the high-voltage inner coil 22, and the outer side surface of the outer radial limiting block 35 abuts against the inner side surface of the end portion of the high-voltage outer coil 23. The inner radial limiting block 34 and the outer radial limiting block 35 can respectively keep the relative positions of the low-voltage coil 21 and the high-voltage inner coil 22 and the relative positions of the high-voltage inner coil 22 and the high-voltage outer coil 23, and are suitable for the structure of the grounding transformer. In other embodiments, the transformer can also be a conventional distribution transformer, and the coils have two groups of inner and outer coils, and at this time, one specification of radial limiting block can be arranged.

[0032] The spacer 32 is provided with a limiting groove, the radial limiting block has a part adapted to extend into the limiting groove, and the limiting groove on the spacer 32 has two parts for the inner radial limiting block 34 and the outer radial limiting block 35 to extend into respectively, so that the radial limiting blocks can be limited by the spacer 32, the installation position of the radial limiting blocks is ensured, and the limiting reliability is improved. In other embodiments, the spacer can also not be provided with a limiting groove, and the radial limiting block directly abuts against the side of the coil facing the coil.

[0033] An insulation cylinder is arranged between the two adjacent groups of coils, an inner insulation cylinder 24 is arranged between the low-voltage coil 21 and the high-voltage inner coil 22, an outer insulation cylinder 25 is arranged between the high-voltage inner coil 22 and the high-voltage outer coil 23, and the axial length of the insulation cylinder is greater than the axial length of the coil to ensure the insulation performance. The radial limiting block is provided with a slot for the end of the insulation cylinder to be inserted into, the slot extends to the part of the radial limiting block extending into the limiting groove of the spacer 32, the slot of the radial limiting block can fix the insulation cylinder, and the depth of the slot is relatively large, the bottom of the slot is located at the part of the radial limiting block extending into the limiting groove of the spacer 32, so that the insulation cylinder also extends into the space of the limiting groove of the spacer 32, and the fixing effect of the spacer 32 and the radial limiting block is improved. In other embodiments, the axial length of the insulation cylinder can be smaller than the axial length of the coil, and the depth of the slot is relatively small and does not extend to the part of the radial limiting block extending into the limiting groove of the spacer.

[0034] The width of the slot of the radial limiting block is adapted to the wall thickness of the corresponding insulation cylinder, the insulation cylinder is tightly matched with the radial limiting block, the limiting groove on the spacer 32 constitutes a limiting structure for limiting the radial limiting block, and the relatively long insulation cylinder can also be provided with a space for avoiding the limiting groove. In other embodiments, the radial limiting block can also not be provided with a slot, and a notch is arranged at the end of the insulation cylinder to avoid the radial limiting block to realize the installation of the radial limiting block and the insulation cylinder.

[0035] Since the side of the coil is a curved surface surrounding the core column, in order to better contact the side of the coil, the two opposite sides of the radial limiting block in the radial direction are curved surfaces adapted to the side of the coil, which can be arc surfaces. The arc surfaces constitute limiting surfaces abutting against the coil, the limiting surfaces are matched with the shape of the side of the coil, the radial limiting block can be well attached to the coil, and the stress is uniformly distributed. In other embodiments, the two opposite sides of the radial limiting block can also be flat surfaces, which are not completely matched with the side of the coil.

[0036] The radial limiting block is an elastic block, and the radial limiting block is elastically deformed when abutting against the coil. The elastic block can be made of silicone rubber. The radial limiting block has a certain elasticity, and can play a buffering role when the coil is subjected to the impact of electric power. In other embodiments, the radial limiting block can also be made of relatively hard insulation plastic.

[0037] The cushion block 32 is made of epoxy material, and elastic pads 33 are arranged between the cushion block 32 and each group of coil end portions. The elastic pads 33 are located on the side of the cushion block 32 facing the coil, and each elastic pad 33 covers the part of the corresponding side of the cushion block 32 outside the notch of the limiting groove. The elastic pad 33 can be made of silicone rubber material, and the elastic pad 33 abuts against each group of coil end faces. The cushion block 32 applies a pressing force to the coil through the elastic pad 33, and the upper and lower cushion blocks 32 cooperate with the elastic pad 33 to clamp each group of coils. The elastic pad 33 can play a buffering role when the coil bears an axial force. In other embodiments, the elastic pad can not be provided, and the cushion block directly applies a pressing force to the coil.

[0038] The radial dimension of the part of the radial limiting block located between the adjacent two groups of coils is greater than the radial dimension of the part located in the limiting groove of the cushion block 32. The step formed by the two parts of the radial limiting block abuts on the elastic pads 33 on both sides of the corresponding limiting groove. The insulating cylinder is inserted into the groove bottom of the insertion slot of the radial limiting block, and the radial limiting block extends to the groove bottom of the limiting groove of the cushion block 32. The insulating cylinder cooperates with the cushion block 32 to axially fix the radial limiting block.

[0039] The clamping piece is provided with a mounting plate on which a pressing nail 31 is mounted. The pressing nail 31 is used to press the cushion block 32 tightly. Each cushion block 32 corresponds to two pressing nails 31 which are arranged along the radial direction. The pressing nails 31 constitute a structure on the cushion block 32 for pressing cooperation with the cushion block 32. The double pressing nail 31 support structure increases the axial pressing force of the coil, and ensures that the high and low voltage winding coils do not displace radially in the event of a sudden short circuit. In the embodiment, the upper and lower cushion blocks 32 are fixed by the pressing nails 31. In other embodiments, only the upper cushion block can be fixed by the pressing nail, and the lower cushion block directly abuts against the support plate of the upper and lower clamping pieces. At this time, the support plate constitutes a structure on the cushion block for pressing cooperation with the cushion block.

[0040] The coil of the grounding transformer and the clamping piece adopt a combined support mode of the cushion block 32, the elastic pad 33 and the radial limiting block, which can ensure that the coil of the grounding transformer has high mechanical strength, and reduce the friction force of the radial displacement deformation of the high and low voltage winding coils and the friction force rotating along the circumferential direction. The high-strength cushion block 32 can withstand axial shear force and various combined friction forces, and is not easy to break, while ensuring that the coil does not deform and displace. The elastic pad 33 is arranged between the cushion block 32 and the coil end face, which increases the contact area, uniformly distributes the stress, and increases the friction force. The use of the radial limiting block ensures that the relative positions of the high and low voltage windings are consistent in the event of a sudden short circuit, and the radial displacement does not occur. The winding coil selects 180 heat-resistant grade high-strength semi-hard enameled copper wire, which effectively enhances the ability of the wire to resist yielding, and greatly improves the short-circuit dynamic stability of the winding when the winding is subjected to a sudden short-circuit current impact.

[0041] The low-voltage coil 21 constitutes the innermost group of coils, and the low-voltage coil 21 is closest to the iron core column. The low-voltage coil 21 is arranged in the innermost position of the coil group, and the high-voltage coil 22 is arranged in the outermost position of the coil group. Figure 4As shown, the low-voltage coil 21 and the core column are provided with an inner lining, which is a three-layer structure including two layers of glass cloth board 60 and one layer of silicon rubber support strip 61. The silicon rubber support strip 61 forms an elastic buffer structure, and the silicon rubber support strip 61 is 2 mm thick and located between the two layers of glass cloth board 60. The inner lining can be provided with multiple around the core column. The glass cloth board 60 and the silicon rubber support strip 61 are combined to support, which can avoid the support being not tight, avoid the short-circuiting moment electric force causing the displacement of the silicon rubber support strip 61 due to the vibration of the winding coil, and further cause the displacement deformation of the winding coil when it is contracted inward, and on the other hand, it can avoid the support being too tight, so that the silicon steel sheet of the core 10 is excessively stressed, thereby causing the noise to exceed the standard. In other embodiments, only the glass cloth board can be used as the inner lining.

[0042] As shown in Figure 5 The upper clamp 40 is fixed to the upper yoke 11 of the core 10, and the lead wires of each low-voltage coil 21 are respectively connected with the inner lead copper bar 43 and the outer lead copper bar 44 at the two ends. The side of the upper clamp 40 away from the core 10 is provided with a lead support 41. The lead support 41 and the inner lead copper bar 43 are fixed by four high-strength insulators 42, and the four high-strength insulators 42 are arranged in a matrix. The inner lead copper bar 43 and the outer lead copper bar 44 are fixed by four high-strength insulators 42, and the four high-strength insulators 42 are arranged in a matrix. The outer lead copper bar 44 is higher than the inner lead copper bar 43, so that the mechanical strength of the lead copper bar of the low-voltage coil 21 is greatly improved, and the mutual mechanical force of the inner and outer lead copper bars at the wire inlet is reduced.

[0043] Since the inner side of the high-voltage inner coil 22 of the grounding transformer is close to the low-voltage coil 21, and the outer side is close to the high-voltage outer coil 23, the head lead-out wires of the high-voltage inner coil 22 can only be led out from the upper and lower ends. Conventionally, the lead-out wires are directly used as the lead-out wires of the coil, and the lead-out wires are coated with insulating materials, which is relatively troublesome and the insulation performance is not reliable. In the present embodiment, as shown in Figure 6 and Figure 7 The upper and lower lead-out ends of the high-voltage inner coil 22 are welded with cables 50, which are used as the lead-out wires of the high-voltage inner coil 22. The coil is fixed with an insulating coating layer, which has a certain thickness and can be made of epoxy resin. The welding part of the high-voltage inner coil 22 and the cable 50 is sealed in the insulating coating layer, and the insulating coating layer covers part of the cable sheath. The head and tail lead-out wires of the high-voltage inner coil 22 are 10kV silicon rubber cables 50, and the cross-sectional area of the lead wire of the cable 50 is larger than that of the high-voltage inner coil 22. The cable 50 is welded with the winding lead wire at the end of the coil, and finally the whole is poured and solidified. In this way, the cable 50 and the coil become a whole, which eliminates the safety hazard and improves the mechanical strength of the lead-out wire, and ensures the insulation reliability. In other embodiments, the conventional form of using the lead wire of the coil as the lead-out wire can also be used.

[0044] The grounding transformer has high short-circuit resistance during normal operation and when a short circuit occurs in the system, can withstand short-circuit current impact, and ensures safe and reliable operation of the equipment.

[0045] Finally, it should be noted that the above only for the preferred embodiments of the present application, and is not intended to limit the present application, although the foregoing embodiments of the present application has been described in detail, for those skilled in the art, it still can be recorded in the foregoing each embodiment of the technical solutions of the modification, or part of the technical features of the equivalent replacement. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included within the scope of the present application.

Claims

1. A transformer, comprising an iron core, clamps, and spacers, wherein at least two sets of coils are spaced apart from the inside to the outside on the iron core column, the clamps are clamped onto the iron core and have a structure for pressing against the spacers so that the spacers apply a resisting force to the ends of each set of coils along the coil axial direction, characterized in that, The radially limiting blocks are arranged between the two adjacent groups of coils and abut against the opposite sides of the two adjacent groups of coils to limit the radial distance between the two adjacent groups of coils.

2. The transformer of claim 1, wherein, The spacer is provided with a limiting groove, and the radially limiting block has a portion extending into the limiting groove.

3. The transformer of claim 2, wherein, The two adjacent groups of coils are provided with an insulation cylinder, the axial length of the insulation cylinder is greater than the axial length of the coil, the radially limiting block is provided with a slot for the end of the insulation cylinder to insert, and the slot extends to the portion of the radially limiting block extending into the limiting groove.

4. The transformer of claim 1, wherein, The two adjacent groups of coils are provided with an insulation cylinder, the radially limiting block is provided with a slot for the end of the insulation cylinder to insert, and the spacer is provided with a limiting structure for limiting the radially limiting block.

5. A transformer according to any one of claims 1-4, characterised in that The side of the radially limiting block abutting against the coil is a limiting surface, and the limiting surface is matched with the shape of the side of the coil.

6. A transformer according to any one of claims 1-4, characterised in that The radially limiting block is an elastic block, and the radially limiting block is elastically deformed when abutting against the coil.

7. A transformer according to any one of claims 1-4, characterised in that The spacer and the end of the coil are provided with an elastic pad, the elastic pad abuts against the end of the coil, and the spacer applies a pressing force to the coil through the elastic pad.

8. A transformer according to any one of claims 1-4, characterised in that The transformer is a grounding transformer, and the core column is sequentially sleeved with a low-voltage coil, a high-voltage inner coil and a high-voltage outer coil from inside to outside, the low-voltage coil, the high-voltage inner coil and the high-voltage outer coil respectively form a group of coils, and the radially limiting blocks are arranged between the low-voltage coil and the high-voltage inner coil and between the high-voltage inner coil and the high-voltage outer coil and abut against the side of the end of the coil.

9. A transformer according to any one of claims 1-4, characterised in that The inner lining is arranged between the coil located at the innermost side and the core column, and the inner lining comprises an elastic buffer structure.

10. A transformer according to any one of claims 1-4, characterised in that The cable is welded to the outgoing end of the coil, the cable serves as the outgoing wire of the coil, the coil is fixed with an insulation coating layer outside, and the welding part of the coil and the cable is sealed in the insulation coating layer.

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