A method for manufacturing a voltage transformer

Abstract

The present invention belongs to the technical field of voltage transformers, and particularly relates to a method for manufacturing a voltage transformer. The method comprises the following steps: step S1: manufacturing a mold; step S2: manufacturing a voltage transformer coil body; step S3: vacuum drying the voltage transformer coil body and preheating it, and then heating the mold with the voltage transformer coil body to a constant temperature after molding; step S4: evacuating the inner cavity of the mold and filling it with SF6 gas, and then depressurizing it to normal pressure, so that the inner cavity of the mold is completely in an insulating gas environment; step S5: injecting epoxy resin mixture into the inner cavity of the mold under pressure; step S6: curing the heat-insulating gel; step S7: demoulding, and then curing; step S8: assembling. The present invention has a simple process, convenient operation, short gel curing time, shortened production cycle, small mixture viscosity, stable gel time and glass transition temperature, high mechanical and electrical strength of the product, and small partial discharge.

Description

Technical Field

[0001] The invention belongs to the technical field of voltage transformers, and in particular relates to a method for manufacturing a voltage transformer. Background Art

[0002] Voltage transformer is a device for measuring voltage and electric energy in power system or electrical control system. In recent years, metal-enclosed switchgear (referred to as C-GIS inflatable cabinet) with SF6 as insulating medium has been widely promoted and applied because of its small size, safe operation and applicability to various environments. The voltage transformer matched with it is a dry-type voltage transformer developed and designed in recent years. At present, dry-type voltage transformer has problems such as low partial discharge starting voltage, product operation failure and large partial discharge when the primary terminal is electrically connected. According to the design requirements, switchgear manufacturers and the market particularly need a dry-type voltage transformer with high partial discharge starting voltage, small partial discharge, and safe and reliable operation. Summary of the invention

[0003] In order to solve the problems of low partial discharge starting voltage, large partial discharge amount, unreliable operation, etc. in the existing voltage transformer, the present invention provides a method for manufacturing a voltage transformer.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] The present invention provides a method for manufacturing a voltage transformer, comprising the following steps:

[0006] Step S1: making a mold;

[0007] Step S2: manufacturing a voltage transformer coil body;

[0008] Step S3: vacuum drying the voltage transformer coil body and preheating it, and then heating the mold with the voltage transformer coil body to a constant temperature;

[0009] Step S4: the inner cavity of the mold is evacuated and filled with SF6 gas, and then the pressure is released to normal pressure, so that the inner cavity of the mold is completely in an insulating gas environment;

[0010] Step S5: injecting the epoxy resin mixture into the mold cavity under pressure;

[0011] Step S6: curing the heat-insulating gel;

[0012] Step S7: demoulding and post-curing;

[0013] Step S8: Assembly.

[0014] The mold comprises a static mold assembly and a dynamic mold, wherein the static mold assembly is arranged on a static mold plate of an automatic pressure gel device, and the dynamic mold is arranged on a dynamic mold plate of the automatic pressure gel device. The static mold assembly is provided with an inflation valve, an air release valve, an injection port valve and a thermocouple, and the voltage transformer body coil is hoisted in the static mold assembly; when the dynamic mold plate of the automatic pressure gel device drives the dynamic mold to close the static mold assembly, a closed injection cavity is formed; and the mold reaches a set temperature through a thermocouple.

[0015] The static mold assembly includes a static mold, an upper mold, a lower mold, a left mold and a right mold, wherein the static mold is connected to the static mold plate of the automatic pressure gel equipment, and the upper mold, the lower mold, the left mold and the right mold are combined into a square frame structure and sealed connected to the static mold, the thermocouple is arranged on the upper mold, the lower mold, the left mold and the right mold, and the voltage transformer body coil is installed on the upper mold.

[0016] In step S3, the voltage transformer coil body is vacuum dried and pre-baked to 130±5°C, and then taken out of the oven after being kept at a constant temperature for 2 hours;

[0017] The pre-baking temperature of the left mold and the right mold is 120-130°C, the pre-baking temperature of the upper mold is 115-120°C, and the pre-baking temperature of the lower mold is 110-115°C. The temperature of the upper mold is 5-10°C higher than that of the lower mold.

[0018] In step S2, the process of manufacturing the voltage transformer coil body includes the following steps:

[0019] Step S2.1: Winding the secondary coil;

[0020] The insulating paperboard with capacitor composite paper is wound into a cylinder as a skeleton, the enameled wire is wound outside the skeleton, the capacitor composite paper is used for interlayer insulation, and the insulating paperboard and capacitor composite paper are wound on the outermost side of the enameled wire to form a main insulating layer;

[0021] Step S2.2: Winding a coil once;

[0022] A shielding copper foil is added to the outside of the wound secondary coil, leaving a gap at the head and tail ends, and an N-end insulated wire is welded to the shielding copper foil to lead out. A piece of shaped copper foil is led out of the shielding copper foil and welded to the enameled wire of the primary coil. A layer of semi-conductive crepe paper is half-stacked on the outside of the shielding copper foil, and capacitor composite paper is added to the outside of the semi-conductive crepe paper, and then the enameled wire is wound to form a primary coil;

[0023] A whole sheet of semi-conductive crepe paper I is added to the primary coil, silicone strips are pressed on both long sides of the semi-conductive crepe paper I, and multiple through holes are symmetrically punched on both sides of the end of the semi-conductive crepe paper I, and the multiple through holes are located at the bottom of the primary coil, so as to form a high-voltage shielding layer on the outside of the primary coil;

[0024] Step S2.3: assembling the iron core;

[0025] The iron core is two butt-jointed C-shaped iron cores. The two C-shaped iron cores are first wrapped with half-stacked PVC self-adhesive tape, and then covered with heat shrink sleeves. The secondary coil and the primary coil are covered on the core column of the iron core. The two C-shaped iron cores are fixed with steel belts, which are located between the heat shrink sleeves and the half-stacked PVC self-adhesive tapes.

[0026] Step S2.4: Perform semi-finished product testing; after the testing, seal the exposed C-shaped core cross-section joints with glue, and seal the gaps between the two side end surfaces of the secondary coil and the core with sealant;

[0027] Step S2.5: bandaging the body of the device;

[0028] Use foamed silicone sheet to insulate and buffer the iron core, seal the outside of the foamed silicone sheet with butt-jointed PVC self-adhesive tape, and then half-fold semi-conductive crepe paper II for shielding and wrapping to form a low-voltage shielding layer;

[0029] Step S2.6: Device body test.

[0030] In step S4, the mold is evacuated to an ultimate vacuum below -0.1 MPa and maintained for 2 minutes, and then filled with SF6 gas to 0.05-0.1 MPa, and the pressure is released to normal pressure after being maintained for 2 minutes.

[0031] In step S5, the epoxy resin mixture is prepared by the automatic control system of the static mixing equipment, and the temperature of the epoxy resin mixture is 70-75°C; the epoxy resin mixture is pressure-injected by the automatic control system of the pressure gel equipment, and fills the inner cavity of the mold, the injection pressure is 0.10-0.15MPa, and the injection speed is slowed down at the beginning and controlled at 1-2kg per minute. When the injection weight exceeds 6kg, the total filling time is controlled at 10-12min.

[0032] In step S6, after the mold is filled with epoxy resin mixture, the pressure is maintained at 0.35-0.4 MPa, and the curing and demoulding are maintained for 60±1 min, and the burrs are removed. The product is unloaded and put into the furnace for further curing within 20 min.

[0033] In step S7, when post-curing is continued, the oven automatic control system maintains a constant temperature of 135±5°C for at least 12 hours, and then uniformly decreases to 50°C over 6 hours before being taken out.

[0034] In step S8, the cured injection molding body is fixed to the primary and secondary terminal screws and the base plate, and the voltage transformer is completed.

[0035] The advantages and beneficial effects of the present invention are:

[0036] The scheme is simple and the operation is convenient: the present invention manufactures the voltage transformer body coil by combining the automatic pressure gel equipment and the static mixing equipment, and the material preparation, mixing and injection of heat-insulating and pressure-maintaining gel curing are completed automatically, and SF6 gas is filled for production. The overall scheme is simple and the operation is convenient.

[0037] The gel curing time is short, and the production cycle is shortened: the present invention adopts the pressure gel APG equipment to produce, the epoxy resin static mixing preparation cycle is short, the gel curing time is short, and the production cycle is shortened.

[0038] High mechanical and electrical strength, small partial discharge: The present invention adopts static mixer pressure injection, the solidified material has high density, high mechanical and electrical strength, is filled with SF6 gas, has high partial discharge starting voltage, small partial discharge, and the product can operate safely.

[0039] The viscosity of the mixed material is small, and the gel time and glass transition temperature are stable: the present invention adopts static mixing equipment to prepare the materials for premixing. The static mixer has accurate proportions and can be used immediately after mixing. The viscosity of the mixed material is small, and the gel time and glass transition temperature are stable.

[0040] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0041] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] 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:

[0043] Figure 1 A flowchart of a method for manufacturing a voltage transformer according to the present invention;

[0044] Figure 2 It is a structural schematic diagram of the automatic pressure gel injection mold of the voltage transformer in the present invention;

[0045] Figure 3 It is a left view of the automatic pressure gel injection mold for the voltage transformer in the present invention;

[0046] Figure 4 It is a schematic diagram of the mold closing movement of the movable mold in the automatic pressure gel injection mold of the voltage transformer in the present invention;

[0047] Figure 5 It is a schematic diagram of the structure of the coil of the device body in the present invention;

[0048] Figure 6 for Figure 5 Side view of

[0049] Figure 7 for Figure 5 A local enlarged view of point A in FIG.

[0050] Figure 8 for Figure 5 A local enlarged view of point B in FIG.

[0051] Fig. 9 The figure is a flowchart of the method for manufacturing the device body coil in the present invention.

[0052] In the figure: 1-static mold; 2-movable mold; 3-upper mold; 4-lower mold; 5-left mold; 6-right mold; 7-pressure gauge; 81-first thermocouple; 82-second thermocouple; 83-third thermocouple; 84-fourth thermocouple; 9-inflation valve; 10-deflation valve; 11-injection port valve; 12-static mold plate of automatic pressure gelation equipment; 13-movable mold plate of automatic pressure gelation equipment; 14-upper mold sub-plate; 15-thermocouple pressure plate; 16- Demolding pull plate, 17-iron core, 18-secondary coil, 19-primary coil, 20-high voltage shielding layer, 21-main insulating layer, 22-skeleton, 23-through hole, 24-silicone strip, 25-semi-conductive crepe paper I, 26-half-folded PVC self-adhesive tape, 27-heat shrink sleeve, 28-foamed silicone sheet, 29-butt PVC self-adhesive tape, 30-semi-conductive crepe paper II, 31-C-type iron core section joint, 32-mixed silicone rubber. DETAILED DESCRIPTION

[0053] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0055] See also Figure 1 As shown, the present invention provides a method for manufacturing a voltage transformer, which has simple process, convenient operation, short gel curing time, shortened production cycle, small mixed material viscosity, stable gel time and glass transition temperature, high mechanical and electrical strength of the product, and small partial discharge. Figure 1As shown, the voltage transformer manufacturing method comprises the following steps:

[0056] Step S1: making a mold;

[0057] Step S2: manufacturing a voltage transformer coil body;

[0058] Step S3: vacuum drying the voltage transformer coil body and preheating it, and then heating the mold with the voltage transformer coil body to a constant temperature;

[0059] Step S4: the inner cavity of the mold is evacuated and filled with SF6 gas, and then the pressure is released to normal pressure, so that the inner cavity of the mold is completely in an insulating gas environment;

[0060] Step S5: injecting the epoxy resin mixture into the mold cavity under pressure;

[0061] Step S6: curing the heat-insulating gel;

[0062] Step S7: demoulding and post-curing;

[0063] Step S8: Assembly.

[0064] See also Figures 2 to 4 As shown, in an embodiment of the present invention, the mold includes a static mold assembly and a dynamic mold 2, wherein the static mold assembly is arranged on a static mold plate 12 of an automatic pressure gelation device, and the dynamic mold 2 is arranged on a dynamic mold plate 13 of an automatic pressure gelation device. An inflation valve 9, an air release valve 10, an injection port valve 11 and a thermocouple are provided on the static mold assembly, and the voltage transformer body coil is hoisted in the static mold assembly; when the dynamic mold plate 13 of the automatic pressure gelation device drives the dynamic mold 2 to close the mold with the static mold assembly, a closed injection cavity is formed; the mold reaches the set temperature through the thermocouple.

[0065] In the embodiment of the present invention, the static mold assembly includes a static mold 1, an upper mold 3, a lower mold 4, a left mold 5 and a right mold 6, wherein the static mold 1 is connected to the static mold plate 12 of the automatic pressure gelation equipment, the upper mold 3, the lower mold 4, the left mold 5 and the right mold 6 are combined into a square frame structure and sealedly connected to the static mold 1, the thermocouple is arranged on the upper mold 3, the lower mold 4, the left mold 5 and the right mold 6, and the voltage transformer body coil is installed on the upper mold 3. After the movable mold 2 and the static mold assembly are molded together, the movable mold 2 and the static mold assembly are connected by a demoulding pull plate 16.

[0066] In the embodiment of the present invention, grooves for installing thermocouples are provided on the outer surfaces of the upper mold 3, the lower mold 4, the left mold 5 and the right mold 6, and each thermocouple is pressed and fixed by a thermocouple pressing plate 15; multiple thermocouples are connected to the mold constant temperature automatic control system. Specifically, a first thermocouple 81 is provided on the left mold 5, a second thermocouple 82 is provided on the lower mold 4, a third thermocouple 83 is provided on the right mold 6, and a fourth thermocouple 84 is provided on the upper mold 3. Since the static mold 1 is fixed on the static mold plate 12 of the automatic pressure gelation equipment, and the dynamic mold 2 is fixed on the dynamic mold plate 13 of the automatic pressure gelation equipment, the static mold 1 and the dynamic mold 2 do not need to carry thermocouples, and are heated by the static mold plate 12 of the automatic pressure gelation equipment and the dynamic mold plate 13 of the automatic pressure gelation equipment to make the overall temperature of the mold consistent.

[0067] Furthermore, an inflation port and an air release port are arranged on the upper mold 3, and an inflation valve 9 and an air release valve 10 are arranged on the inflation port and the air release port respectively; an upper mold sub-plate 14 for installing the voltage transformer body coil is arranged on the inner side of the upper mold 3; an injection port is arranged at the lower part of the left mold 5 or the right mold 6, and an injection port valve 11 is arranged on the injection port.

[0068] See also Figures 2 to 4 As shown, the inner surfaces of the static mold assembly and the movable mold 2 are electroplated with chrome to increase hardness, extend service life, reduce material costs, and improve production efficiency.

[0069] When in use, first fix the static mold 1 and the dynamic mold 2 to the static mold plate 12 and the dynamic mold plate 13 of the automatic pressure gel equipment respectively for preheating; then fix the preheated voltage transformer body coil on the upper mold sub-plate 14, and then fix the upper mold sub-plate 14 together with the voltage transformer body coil on the upper mold 3, assemble the upper mold 3, the lower mold 4, the left mold 5, the right mold 6 together with the inflation valve 9 and the deflation valve 10, the injection port valve 11 and the fixing bolts and fix them on the static mold 1, start the hydraulic device of the automatic pressure gel equipment, translate the dynamic mold 2 through the dynamic mold plate 13 of the automatic pressure gel equipment, close the mold, and finally fix the demoulding pull plate 16 on the left mold 5, and the automatic control system of the pressure gel equipment keeps the temperature and pressure.

[0070] Furthermore, the deflation valve 10 is connected to the pressure gauge 7 and the vacuum pump, the charging valve 9 is connected to the SF6 gas bottle, the injection port valve 11 is connected to the static mixer, and the SF6 gas is recovered through the recovery device.

[0071] In step S3, the voltage transformer coil body is vacuum dried and pre-baked to 130±5°C, and then taken out of the oven after being kept at a constant temperature for 2 hours; the pre-baking temperature of the left mold 5 and the right mold 6 is 120-130°C, the pre-baking temperature of the upper mold 3 is 115-120°C, and the pre-baking temperature of the lower mold 4 is 110-115°C, and the temperature of the upper mold 3 is 5-10°C higher than that of the lower mold 4. The mold temperature setting can be adjusted during injection and needs to meet the above requirements.

[0072] See also Figures 5 to 9 As shown, in the embodiment of the present invention, in step S2, the process of manufacturing the voltage transformer coil body includes the following steps:

[0073] Step S2.1: Winding the secondary coil 18;

[0074] The insulating paperboard with capacitor composite paper is wound into a cylinder as a skeleton 22, the enameled wire is wound outside the skeleton 22, the capacitor composite paper is used for interlayer insulation, and the insulating paperboard and the capacitor composite paper are wound on the outermost side of the enameled wire to form a main insulating layer 21;

[0075] Step S2.2: Winding a primary coil 19;

[0076] A shielding copper foil is added to the wound secondary coil 18 in the middle, leaving a gap at the head and tail ends, and an N-terminal insulated wire is welded to the shielding copper foil to lead out. A piece of shaped copper foil is led out of the shielding copper foil and welded to the enameled wire of the primary coil 19. A layer of semi-conductive crepe paper is half-stacked on the outside of the shielding copper foil, and capacitor composite paper is added to the outside of the semi-conductive crepe paper and then the enameled wire is wound to form the primary coil 19;

[0077] A whole sheet of semi-conductive corrugated paper I 25 is added to the primary coil 19, and silicone strips 24 are pressed on both long sides of the semi-conductive corrugated paper I 25, and multiple through holes 23 are symmetrically punched on both sides of the end of the semi-conductive corrugated paper I 25. The multiple through holes 23 are located at the bottom of the primary coil 19, and the through hole 23 located in the middle is directly opposite to the primary high-voltage lead-out line on the opposite side, which is conducive to gas discharge during pressure injection, thereby forming a high-voltage shielding layer 20 on the outside of the primary coil 19;

[0078] Step S2.3: assembling the iron core 17;

[0079] The iron core 17 is two butt-jointed C-shaped iron cores. The two C-shaped iron cores are first wrapped with a half-lapped PVC self-adhesive tape 26, and then a heat shrink sleeve 27 is installed. The secondary coil 18 and the primary coil 19 are installed on the core column of the iron core 17. The two C-shaped iron cores are fixed with a steel belt, and the steel belt is located between the heat shrink sleeve 27 and the half-lapped PVC self-adhesive tape 26;

[0080] Step S2.4: Conduct semi-finished product testing; after the test, the exposed C-shaped core cross-section joint 31 is sealed with glue, and the gap between the two side end surfaces of the secondary coil 18 and the core 17 is sealed with mixed silicone rubber 32;

[0081] Step S2.5: bandaging the body of the device;

[0082] Use a hot air gun to blow the silicone rubber heat shrink sleeve 27 to shrink and stick it to the outer surface of the iron core 17, tightly combine with the iron core 17 to prevent resin from entering; use a foamed silicone plate 28 to insulate and buffer the iron core 17, and use a butt-jointed PVC self-adhesive tape 29 to seal the outside of the foamed silicone plate 28, and then half-fold the semi-conductive crepe paper II 30 for shielding and wrapping to form a low-voltage shielding layer;

[0083] Step S2.6: device body test;

[0084] After the device body is wrapped, the error, excitation characteristics and voltage resistance tests are carried out.

[0085] The coil body of the voltage transformer is wrapped with a foamed silicone sheet 28, which will not cause the epoxy resin pressure injection gel to solidify and produce a large stress on the iron core 17, so that the performance of the voltage transformer iron core is stable; the high and low voltage shielding works together to reduce the local discharge of the voltage transformer, thereby achieving the purpose of safe operation of the voltage transformer.

[0086] In an embodiment of the present invention, in step S4, the mold is evacuated to an ultimate vacuum below -0.1 MPa and maintained for 2 minutes, filled with SF6 gas to 0.05-0.1 MPa, and then released to normal pressure after maintaining for 2 minutes.

[0087] In step S5, the epoxy resin mixture is prepared by the automatic control system of the static mixing equipment, and the temperature of the epoxy resin mixture is 70-75°C; the epoxy resin mixture is pressure-injected by the automatic control system of the pressure gel equipment, and fills the inner cavity of the mold, and the injection pressure is 0.10-0.15MPa (1.0-1.5kgf). At the beginning, the injection speed is slowed down and controlled at 1-2kg per minute. When the injection weight exceeds 6kg, the total filling time is controlled at 10-12min.

[0088] In step S6, after the mold is filled with epoxy resin mixture, the pressure is maintained at 0.35-0.4MPa (3.5-4kgf) for 60±1min for curing and demoulding, and the burrs are removed. The product is unloaded and put into the furnace for further curing within 20min.

[0089] In step S7, when post-curing is continued, the oven automatic control system maintains a constant temperature of 135±5°C for at least 12 hours, and then uniformly decreases to 50°C over 6 hours before being taken out.

[0090] In step S8, the cured injection molding body is fixed to the primary and secondary terminal screws and the base plate, and the voltage transformer is completed.

[0091] When the product is in use, the primary high-voltage terminal is mechanically connected to the high-voltage component to achieve electrical contact with the high-voltage part. After the voltage transformer base plate is fixed and installed, the secondary cable is connected. After the remaining components are installed, the installation of this voltage transformer is completed.

[0092] The present invention provides a method for manufacturing a voltage transformer. By combining an automatic pressure gelling device and a static mixing device, the material preparation, mixing, injection, heat preservation and pressure maintaining gel curing are automatically completed, and SF6 gas is filled for manufacturing. The overall solution is simple and easy to operate. Static mixing equipment is used to prepare and premix materials. The static mixer has an accurate ratio and can be used immediately after mixing. The viscosity of the mixed material is small, and the gel time and glass transition temperature are stable. The static mixer is used for pressure injection. The solidified material has a high density, high mechanical and electrical strength, and is filled with SF6 gas. The local discharge starting voltage is high, the local discharge amount is small, and the product can operate safely. The automatic pressure gelling device is used for manufacturing, and the gel curing time is short, shortening the production cycle.

[0093] The above description is only an embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, expansion, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for manufacturing a voltage transformer, characterized in that: The following steps are involved: Step S1: making a mold; Step S2: manufacturing a voltage transformer coil body; Step S3: vacuum drying the voltage transformer coil body and preheating it, and then heating the mold with the voltage transformer coil body to a constant temperature; Step S4: the inner cavity of the mold is evacuated and filled with SF6 gas, and then the pressure is released to normal pressure, so that the inner cavity of the mold is completely in an insulating gas environment; Step S5: injecting the epoxy resin mixture into the mold cavity under pressure; Step S6: curing the heat-insulating gel; Step S7: demoulding and post-curing; Step S8: assembling; In step S5, the epoxy resin mixture is prepared by using an automatic control system of a static mixing device, and the temperature of the epoxy resin mixture is 70-75°C; the epoxy resin mixture is pressure-injected by an automatic control system of a pressure gelling device, and fills the inner cavity of the mold, and the injection pressure is 0.10-0.15MPa. At the beginning, the injection speed is slowed down and controlled at 1-2kg per minute. When the injection weight exceeds 6kg, the total filling time is controlled at 10-12min; In step S2, the process of manufacturing the voltage transformer coil body includes the following steps: Step S2.1: Winding the secondary coil (18); Insulating paperboard sandwiched with capacitor composite paper is wound into a cylinder as a skeleton (22), enameled wire is wound outside the skeleton (22), capacitor composite paper is used for interlayer insulation, and insulating paperboard and capacitor composite paper are wound on the outermost side of the enameled wire to form a main insulating layer (21); Step S2.2: Winding a coil (19); A shielding copper foil is placed outside the wound secondary coil (18) in the middle, leaving a gap at the head and tail ends, a primary N-end insulated wire is welded to the shielding copper foil, a piece of shaped copper foil is led out of the shielding copper foil and welded to the enameled wire of the primary coil (19), a layer of semi-conductive crepe paper is half-lapped on the outside of the shielding copper foil, capacitor composite paper is added to the outside of the semi-conductive crepe paper, and then the enameled wire is wound to form a primary coil (19); A whole sheet of semi-conductive corrugated paper I (25) is applied to the primary coil (19), silicone strips (24) are pressed on both long sides of the semi-conductive corrugated paper I (25), and a plurality of through holes (23) are symmetrically punched on both sides of the end of the semi-conductive corrugated paper I (25), and the plurality of through holes (23) are located at the bottom of the primary coil (19), thereby forming a high-voltage shielding layer (20) on the outside of the primary coil (19); Step S2.3: assembling the iron core (17); The iron core (17) is two butt-jointed C-shaped iron cores. The two C-shaped iron cores are first wrapped with a half-lapped PVC self-adhesive tape (26), and then a heat shrink sleeve (27) is put on. The secondary coil (18) and the primary coil (19) are put on the core column of the iron core (17). The two C-shaped iron cores are fixed with a steel belt, and the steel belt is located between the heat shrink sleeve (27) and the half-lapped PVC self-adhesive tape (26); Step S2.4: Conducting semi-finished product testing; after the testing, the exposed C-shaped core cross-section joint (31) is sealed with glue, and the gap between the two side end surfaces of the secondary coil (18) and the core (17) is sealed with sealant; Step S2.5: bandaging the body of the device; The iron core (17) is insulated and buffered by using a foamed silica gel sheet (28), the outside of the foamed silica gel sheet (28) is sealed tightly by using a butt-jointed PVC self-adhesive tape (29), and then a semi-conductive crepe paper II (30) is half-folded for shielding and wrapping to form a low-voltage shielding layer; Step S2.6: Device body test.

2. The method for manufacturing a voltage transformer according to claim 1, characterized in that: The mold comprises a static mold assembly and a dynamic mold (2), wherein the static mold assembly is arranged on a static mold plate (12) of an automatic pressure gelling device, and the dynamic mold (2) is arranged on a dynamic mold plate (13) of the automatic pressure gelling device, and an inflation valve (9), an air release valve (10), an injection port valve (11) and a thermocouple are provided on the static mold assembly, and the voltage transformer body coil is hoisted in the static mold assembly; when the dynamic mold plate (13) of the automatic pressure gelling device drives the dynamic mold (2) to close the static mold assembly, a closed injection cavity is formed; and the mold reaches a set temperature through the thermocouple.

3. The method for manufacturing a voltage transformer according to claim 2, characterized in that: The static mold assembly comprises a static mold (1), an upper mold (3), a lower mold (4), a left mold (5) and a right mold (6), wherein the static mold (1) is connected to a static mold plate (12) of an automatic pressure gelling device, the upper mold (3), the lower mold (4), the left mold (5) and the right mold (6) are combined into a square frame structure and sealedly connected to the static mold (1), the thermocouple is arranged on the upper mold (3), the lower mold (4), the left mold (5) and the right mold (6), and the voltage transformer body coil is installed on the upper mold (3).

4. The method for manufacturing a voltage transformer according to claim 3, characterized in that: In step S3, the voltage transformer coil body is vacuum dried and pre-baked to 130±5°C, and then taken out of the oven after being kept at a constant temperature for 2 hours; The pre-baking temperature of the left mold (5) and the right mold (6) is 120-130°C, the pre-baking temperature of the upper mold (3) is 115-120°C, and the pre-baking temperature of the lower mold (4) is 110-115°C. The temperature of the upper mold (3) is 5-10°C higher than that of the lower mold (4).

5. The method for manufacturing a voltage transformer according to claim 1, characterized in that: In step S4, the mold is evacuated to an ultimate vacuum below -0.1 MPa and maintained for 2 minutes, and then filled with SF6 gas to 0.05-0.1 MPa, and the pressure is released to normal pressure after being maintained for 2 minutes.

6. The method for manufacturing a voltage transformer according to claim 1, characterized in that: In step S6, after the mold is filled with epoxy resin mixture, the pressure is maintained at 0.35-0.4 MPa, and the curing and demoulding are maintained for 60±1 min, and the burrs are removed. The product is unloaded and put into the furnace for further curing within 20 min.

7. The method for manufacturing a voltage transformer according to claim 1, characterized in that: In step S7, when post-curing is continued, the oven automatic control system maintains a constant temperature of 135±5°C for at least 12 hours, and then uniformly decreases to 50°C over 6 hours before being taken out.

8. The method for manufacturing a voltage transformer according to claim 1, characterized in that: In step S8, the cured injection molding body is fixed to the primary and secondary terminal screws and the base plate, and the voltage transformer is completed.

Images