A dry-type transformer and its production process

Abstract

A dry-type transformer and its production process, the dry-type transformer comprises a base, two lower clamps installed on the base, three iron cores installed on the lower clamps at intervals, two upper clamps installed on both sides of the top of the iron core, three high and low voltage coil groups respectively sleeved on the three iron cores, and a body insulation member arranged on the high and low voltage coil groups and a hardware connector for connecting the high and low voltage coil groups and the iron core, and its production process comprises step 1, winding a high voltage coil; step 2, winding a low voltage coil; step 3, assembling the high voltage coil of step 1, the low voltage coil of step 2, the iron core, the base, the upper clamp, the lower clamp, the body insulation member and the hardware connector. The high voltage coil of the dry-type transformer of the present invention is not easy to crack and has a longer service life.

Description

Technical Field

[0001] The invention relates to the field of transformers, and in particular to a dry-type transformer and a production process thereof. Background Art

[0002] DMD epoxy prepreg material is made of polyester film, polyester fiber non-woven soft composite material (F grade DMD) impregnated with heat-resistant modified epoxy resin and baked.

[0003] Features and uses of DMD epoxy prepreg materials: The epoxy resin coated contains active groups such as epoxy and amine groups, which cure quickly at medium and high temperatures, firmly bond with copper foil, and produce no low-molecular volatiles during drying and curing, forming an insulation structure with extremely low shrinkage. The product is widely used for interlayer insulation of low-voltage coils of dry-type transformers, and can also be used for slot insulation and phase insulation of F-class motors.

[0004] Pre-impregnated DMD is a three-layer composite material made of polyester film with high melting point polyester non-woven fabrics adhered on both sides, which is then impregnated with high temperature resistant modified epoxy resin and dried into a semi-cured soft composite material.

[0005] Glass fiber mesh cloth is based on glass fiber woven fabric, which is soaked in polymer anti-emulsion coating. It has good alkali resistance, flexibility and high tensile strength in warp and weft directions, and can be widely used in building internal and external wall insulation, waterproofing, fire prevention, crack resistance, etc. Glass fiber mesh cloth is mainly alkali-resistant glass fiber mesh cloth. It is made of medium alkali-free glass fiber yarn (the main component is silicate, with good chemical stability) through a special organizational structure-gauze organization, and then treated with high temperature heat setting such as anti-alkali liquid and reinforcing agent. Curing agent: The curing agent of the project is methyltetrahydrophthalic anhydride, also known as methyltetrahydrophthalic anhydride, MTHPA. Molecular formula: C9H10O3. Molecular weight 166.17. Light yellow liquid, relative density 1.21, freezing point below ~15℃, viscosity (25℃) 50~80mPa·s, refractive index 1.498, good stability in air. Boiling point: 115~155℃, not easy to precipitate crystals, non-toxic. This product is an anhydride epoxy resin curing agent, which has excellent properties such as long-term storage at room temperature, low freezing point, low volatility, low toxicity, etc. It is widely used in impregnation, casting and winding of motors, dry-type transformers, high-voltage switches, mutual inductors, line output transformers, household capacitors, power capacitors and resistors, and integrated circuits.

[0006] Epoxy resin: Epoxy resin is a general term for a class of polymers containing two or more epoxy groups in the molecule. It is a condensation product of epichlorohydrin and bisphenol A or polyols. Due to the chemical activity of the epoxy group, it can be opened with a variety of compounds containing active hydrogen, cured and cross-linked to form a network structure, so it is a thermosetting resin.

[0007] Resin cast dry-type transformers have been widely used in various power-using places due to their safe and stable operation, pollution-free, low noise, and maintenance-free advantages. However, the problems of resin cast dry-type transformers are unstable quality after casting, often with many air gaps, poor mechanical and insulation properties of resin, and difficulty in demoulding, resulting in unqualified test indicators such as partial discharge of the coil and power frequency withstand voltage after casting, as well as process defects. Summary of the invention

[0008] The present invention provides a dry-type transformer and a production process thereof, the main purpose of which is to improve the quality of resin casting process and solve the defects of high partial discharge.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] A dry-type transformer comprises a base, an iron core mounted on the base, three high- and low-voltage coil groups respectively sleeved on the three iron cores, a body insulator arranged on the high- and low-voltage coil groups, and hardware connectors for connecting the high- and low-voltage coil groups and the iron cores, the high-voltage coil is wound through a high-voltage coil mold for winding the high-voltage coil, a high-voltage coil winding machine for rotating the high-voltage coil mold, a resin casting machine for casting the high-voltage coil mold, and a pair of curing and drying ovens for curing and drying the high-voltage coil mold The high-voltage coil is processed in sequence, comprising a first insulating layer composed of several layers wound by the high-voltage coil winding machine, a winding wire arranged in the first insulating layer and wound by the high-voltage coil winding machine, a plurality of first air ducts arranged at intervals in the first insulating layer, and six connecting terminals connected to the winding wire through tap leads, the distance between adjacent tap leads is 15 to 20 mm, the distance between the tap lead and the unconnected connecting terminal is ≥10 mm, and the number of turns of the tap lead is 16:15:15:15.

[0011] Furthermore, the first insulating layer includes an inner first insulating layer wound by the high-voltage coil mold, an interlayer first insulating layer wound on one side of the inner first insulating layer, an outer first insulating layer wound on the other side of the interlayer first insulating layer, and an air duct insulation layer wound on the first air duct, and the distance between the tap lead and the outermost layer of the first insulating layer is 15 to 20 mm.

[0012] Furthermore, the portion of the inner interlayer insulation of the high-voltage coil that extends beyond the conductor is covered with an insulating tape.

[0013] Furthermore, the low-voltage coil is manufactured by a low-voltage coil mold for winding the low-voltage coil and a low-voltage coil winding machine for rotating the low-voltage coil mold. Several layers of the second insulating layer are wound on the low-voltage coil mold by using the low-voltage coil winding machine, and a layer of polypropylene film coating is applied on the contact surface between the low-voltage coil mold and the second insulating layer.

[0014] A dry-type transformer production process, the production process is used to produce the above-mentioned dry-type transformer, the production process steps include:

[0015] Step 1: Winding the high voltage coil;

[0016] Step 2: Winding the low voltage coil;

[0017] Step 3: Assemble the high-voltage coil of step 1, the low-voltage coil of step 2, the iron core, the base, the upper clamp, the lower clamp, the body insulation and the hardware connectors;

[0018] Furthermore, the step 1 is composed of the following steps in sequence:

[0019] Step 1a, installing the high-voltage coil mold on the high-voltage coil winding machine for rotation, and preparing the high-voltage coil mold process;

[0020] Step 1b, winding the winding wire and the first insulating layer on the high-voltage coil mold and inserting a plurality of airway rods arranged at intervals, connecting the winding wire to the terminal, applying a layer of mold release agent between the first insulating layer and the high-voltage coil, and performing the first coil winding process to finally obtain the first coil;

[0021] Step 1c, sending the first coil of step 1b into a curing drying oven for drying at a temperature of 120 to 140 degrees Celsius for 9 to 12 hours;

[0022] Step 1d, sending the first coil dried in step 1c into a resin casting machine for a casting process;

[0023] Step 1e, sending the first coil cast in step 1d into a curing and drying oven for a curing and drying process;

[0024] Step 1f, demoulding and cooling the first coil in step 1e;

[0025] Step 1g, grinding and trimming the outer surface of the high-voltage coil obtained in step 1f to make its end flat and smooth, and performing a trimming process to obtain a high-voltage coil;

[0026] Step 1h. After the pouring in step 1d is completed, the mixing tank of the resin pouring machine is cleaned, and alcohol is used as a cleaning agent. During the cleaning, the cleaning agent is automatically drawn into the mixing tank by a pipeline. During the cleaning, the mixing tank is in a sealed state. After the cleaning is completed, the cleaning agent is discharged from the mixing tank through the waste liquid port, and the discharged and collected cleaning waste liquid is obtained. The cleaning waste liquid is allowed to stand to obtain a supernatant of alcohol and a precipitate of resin. The supernatant can be reused for cleaning the mixing tank to perform a cleaning process.

[0027] On the one hand, by recycling the supernatant for secondary use, the use of cleaning agents can be saved and the purchase cost of cleaning agents can be reduced. On the other hand, by recycling the precipitated resin, it can be sold separately, turning waste into treasure and saving the cost of waste treatment, killing two birds with one stone.

[0028] The step 2 is composed of the following steps in sequence:

[0029] Step 2a, installing the low-voltage coil mold on the foil winding machine for rotation, and preparing the low-voltage coil mold process;

[0030] Step 2b, winding the second insulating layer and the copper foil on the low-voltage coil mold, installing two copper bars arranged at intervals, a plurality of lead pieces arranged at intervals and a temperature control probe tube tied to a lead piece, and performing a second coil winding process to obtain a second coil;

[0031] Step 2c, placing the second coil obtained in step 2b into a drying oven at a temperature of 120 to 140 degrees Celsius for 9 to 11 hours to perform a drying process for the second coil;

[0032] Step 2d, taking out the second coil processed in step 2c, performing a terminal sealing process using room temperature epoxy resin, and standing for 2 hours to cool;

[0033] Step 2e: remove the low-voltage coil mold from the second coil after the end-capping process and perform a demoulding process to obtain a low-voltage coil.

[0034] Furthermore, in step 1d,

[0035] Pouring process: Add epoxy resin and curing agent into the mixing tank in a weight ratio of 1:1, heat to 70-80 degrees Celsius, vacuum and stir for 1.5-2 hours to obtain mixture A, and send mixture A into the vacuum tank through the discharge valve to pour the first coil. After the first coil of wire is filled, the following steps are adopted:

[0036] Step 1d1, evacuate the vacuum tank and let it stand for 25 to 45 minutes;

[0037] Step 1d2, breaking the vacuum state in the vacuum tank, then inflating and pressurizing to 2-3 kPa, and maintaining the pressure for 20 minutes;

[0038] Step 1d3, evacuate the vacuum tank and let it stand for 20 to 30 minutes;

[0039] Step 1d4, breaking the vacuum state in the vacuum tank, then inflating and pressurizing it to 2-3 kPa, maintaining the pressure for 20-30 minutes;

[0040] Step 1d5, adjust the pressure to 1 kPa and let it stand for 30 to 60 minutes.

[0041] By adopting the processing technology of secondary vacuum extraction and secondary vacuum breaking and pressurization, the epoxy resin is filled more tightly and the presence of bubbles in the resin is reduced, thereby improving the sealing degree of the resin in the high-voltage coil, improving its insulation effect, making the high-voltage coil less likely to crack, extending the service life of the high-voltage coil, and improving the compressive strength and external impact resistance of the high-voltage coil.

[0042] Furthermore, in step 1e, the curing and drying process is carried out in a curing drying oven at a temperature of 80 to 140 degrees Celsius, and includes the following four stages in sequence: (1) the temperature of the first stage is 80 to 95 degrees Celsius, and the temperature is maintained for 3 to 5 hours; (2) the temperature of the second stage is 100 to 110 degrees Celsius, and the temperature is maintained for 2 to 3 hours; (3) the temperature of the third stage is 120 to 140 degrees Celsius, and the temperature is maintained for 3 to 5 hours; (4) the temperature of the fourth stage is cooled to 90 to 110 degrees Celsius, and the temperature is maintained for 2 to 3 hours.

[0043] By adopting a four-stage temperature increase method, the resin in the high-voltage coil is cured more evenly and densely, thereby improving the insulation of the high-voltage coil, improving its electrical shielding effect, making the high-voltage coil less likely to crack, and extending the service life of the high-voltage coil, killing two birds with one stone.

[0044] Furthermore, in step 3, the core is assembled in the following steps in sequence:

[0045] Step 3a, longitudinally shearing the core material;

[0046] Step 3b, transversely shearing the core material that has been longitudinally sheared in step 3a;

[0047] Step 3d, stacking the core raw materials that have been cross-cut in step 3b;

[0048] Step 3e, sealing the stacked core raw materials in step 3d to obtain an iron core;

[0049] In step 3e, the core material is sealed: a room temperature epoxy resin coating is applied to the end of the core, and the coating is left to stand for 2 hours to solidify;

[0050] In step 1b, winding wire: the electromagnetic wire is wound, the electromagnetic wire is arranged and pre-pressed, and then the electromagnetic wire is wrapped with insulating tape to obtain the winding wire, and the epoxy resin mixture is injected to penetrate into the layers of the winding, and the winding is cured and formed, so that the electromagnetic wire and the second insulating layer are combined into one to obtain the winding wire; using the insulating tape to wrap the winding wire can separate the winding wire from the epoxy resin so that the epoxy resin will not penetrate into the winding wire through the gap during pouring, and on the other hand, it plays a role in fixing the winding wire to facilitate the positioning of the winding wire, killing two birds with one stone.

[0051] Furthermore, the copper foil is wound on the low-voltage coil mold for a total of 14 turns, including the following steps: (1) first winding 4 turns and placing a number of lead-out pieces at intervals, (2) winding 4 turns again and placing a number of lead-out pieces at intervals, and (3) finally winding the remaining 6 turns. The second insulation layer includes an inner second insulation layer wound on the low-voltage coil mold, an interlayer second insulation layer wound on both sides of the middle copper foil, and an outer insulation layer and a reinforced second insulation layer wound on the outer side of the outer copper foil. The outer surface of the low-voltage coil is wrapped with three layers of the second insulation layer and then half-wrapped with a heat-shrinkable tape. The starting end and the end end between the copper bar and the inner second insulation layer are respectively provided with a reinforced second insulation layer. The reinforced second insulation layer is padded between the lead row and the adjacent turns in the low-voltage coil. The lower ends of the two lead rows in the low-voltage coil are flush with the copper foil, and the upper and lower ends of the second insulation layer are 15 to 20 mm higher than the low-voltage copper foil. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is the production process flow chart of dry-type transformer.

[0053] Figure 2 This is a structural diagram of a dry-type transformer.

[0054] Figure 3 This is a schematic diagram of the boss lead routing and a simplified diagram of the high-voltage coil.

[0055] Figure 4 This is a top view of the high voltage coil.

[0056] Figure 5 This is a schematic diagram of the structure of the outlet panel.

[0057] Figure 6 This is a schematic diagram of the high-voltage coil winding structure.

[0058] Figure 7 This is a top view of the low-voltage coil.

[0059] Figure 8 It is a structural diagram of the low-voltage coil.

[0060] Fig. 9 This is a schematic diagram of the installation of the body insulation components. DETAILED DESCRIPTION

[0061] The specific embodiments of the present invention will be described below with reference to the accompanying drawings.

[0062] Reference Figure 1-Figure 9 A dry-type transformer comprises a base 21, three high- and low-voltage coil groups respectively sleeved on three iron cores 25, body insulation parts arranged on the high- and low-voltage coil groups, hardware connectors for connecting the high- and low-voltage coil groups and the iron cores 25, a fan 43 installed on the base 21, a fan bracket for installing the fan 43, and a dry-type transformer temperature controller (model BWD-KRE or BWD-K3) for controlling the fan, wherein the three high- and low-voltage coil groups are arranged in a horizontal interval.

[0063] The transformer temperature protection is based on the PT100 linear platinum resistance sensor principle, and the LED displays the temperature. It has temperature settings, can save the highest temperature value, automatically send out an alarm trip signal, and automatically / manually start and stop the fan. The fan adopts an axial flow fan, which has the advantages of large air volume, good heat dissipation effect and quietness.

[0064] The high and low voltage coil assembly includes a low voltage coil 54 sleeved on the middle of the iron core 25 and a high voltage coil 36 sleeved on the outside of the low voltage coil 54 .

[0065] refer to Fig. 9 The device body insulation includes a set of insulating tubes 53 arranged between the low-voltage coil 54 and the high-voltage coil 36 and a plurality of insulating pads spaced apart on the upper and lower sides of the insulating tube 53 . The high-voltage coil 36 is sleeved on the outer side of the insulating tube 53 .

[0066] The insulating pad includes an upper pad 51 disposed above the insulating tube 53 and a lower pad 55 disposed below the insulating tube 53.

[0067] The upper pad 51 and the lower pad 55 are on the same vertical line, the angle between the two upper pads 51 facing the high-voltage lead 32 is 90 degrees, the angle between the two lower pads 55 facing the high-voltage lead 32 is 90 degrees, the angle between the two upper pads 51 facing the low-voltage lead is 90 degrees, and the angle between the two lower pads 55 facing the low-voltage lead is 90 degrees. The insulating pad is cast in a mold by resin, and the pad is iron red. The resin pad is provided with impact resistance and electrical insulation, thereby protecting the stability of the high and low voltage coil groups and reducing the loss of electricity.

[0068] refer to Figure 2The hardware connectors include a high-voltage lead 32 connected to the high-voltage coil 36, a low-voltage lead connected to the low-voltage coil 54, a zero-phase copper busbar installed on the low-voltage lead, a wiring piece installed on the outside of the high-voltage coil 36, a conductive rod installed on the outside of the high-voltage coil 36, two lower clamps 31 installed on the base 21, three iron cores 25 installed on the lower clamps 31 at intervals, and two upper clamps 22 installed on the left and right sides of the top of the iron core 25.

[0069] The lower clamp 31 is arranged on the left and right sides of the bottom of the iron core 25, the upper clamp 22 is a U-shaped channel steel, and the lower clamp 31 is a U-shaped channel steel. Six limiting holes for assembling the iron core 25 are provided on the upper clamp 22 and the lower clamp 31, and screws 24 for installing the iron core 25 are detachably inserted in the limiting holes, so that the iron core 25 is installed on the upper clamp 22 and the lower clamp 31.

[0070] The hardware connectors also include some known dry-type transformer assembly parts such as buffer pads, insulators, high-voltage heat shrink tubes, low-voltage heat shrink tubes, high-voltage U-shaped plates 45, wiring copper tubes, gaskets, screws and nuts, etc.

[0071] The high-voltage lead 32 includes three insulators 26, a plurality of washers, a plurality of spring washers, three high-voltage U-shaped plates, a plurality of copper tubes, a terminal block and a plurality of bolts.

[0072] The low-voltage lead includes a copper busbar with a specification of 8X60, six insulating terminals, a number of bolts, a number of washers, a number of nuts, and a number of double-headed screws.

[0073] The high-voltage coil 36 is manufactured in sequence through a high-voltage coil mold for winding the high-voltage coil 36, a high-voltage coil winding machine for rotating the high-voltage coil mold, a resin pouring machine for pouring the high-voltage coil mold, and a pair of curing and drying ovens for curing and drying the high-voltage coil mold.

[0074] refer to Figure 3-Figure 6 The high-voltage coil 36 includes a first insulating layer composed of several layers wound by a high-voltage coil winding machine, a winding wire 72 arranged in the first insulating layer and wound by the high-voltage coil winding machine, a plurality of first air ducts 76 arranged at intervals in the first insulating layer, six connection terminals 80 connected to the winding wire 72 through tap leads, an incoming terminal 79 arranged at one end of the winding wire 72, an outgoing terminal 81 arranged at the other end of the winding wire 72, and a boss for mounting the incoming terminal 79, the outgoing terminal 81 and the connection terminal 80. The distance between adjacent tap leads is 15 to 20 mm, and the preferred distance of the tap leads when they are routed in the boss is 17 mm. The distance between the tap leads and the unconnected connection terminals is ≥10 mm, and the preferred distance is 12 mm. The number of turns of the tap leads is 16:15:15:15.

[0075] The first insulating layer includes an inner first insulating layer wound by a high-voltage coil mold, an interlayer first insulating layer 73 wound on one side of the inner first insulating layer, an outer first insulating layer 75 wound on the other side of the interlayer first insulating layer 73, and an air duct insulation layer wound on the first air duct 76. The distance between the tap lead and the outermost layer of the first insulating layer is 15 to 20 mm.

[0076] The part of the interlayer insulation inside the high-voltage coil 36 that extends beyond the wire is covered with insulating tape. Specifically, the first interlayer insulating layer 73 extends 5 mm on each side of the wire, and the tap lead is wrapped 3 mm on each side with insulating tape. The insulating tape is a glass fiber mesh cloth, which is used to protect the tap lead from being damaged by excessive temperature inside the high-voltage coil 36.

[0077] Taking the specification of CB10~630 / 10,10±2X2.5% / 4V,Dyn11,UK=6% as an example, the high-voltage coil 36, the winding wire 72 has a total of 637 turns, the rated capacity is 630kVA, the number of turns of the high-voltage coil 36 is 606 turns, the winding inner diameter is 340mm, the connection method is: D, the inner first insulation layer, the interlayer first insulation layer 73, the first air channel 76 first insulation layer and the outer first insulation layer 75 are all made of glass fiber mesh cloth with a specification of 2X340X1 290mm, the material of winding wire 72 is double glass fiber covered flat copper wire 2.12X3.65mm, the reactance height is 310mm, the phase current is 21A, the length of a single conductor is 918m, the inner first insulation layer is 2.5mm, the first insulation layer 73 between layers is 0.4mm thick, the material of the first insulation layer 73 between layers is glass fiber mesh cloth with a specification of 0.4X75mm, the outer first insulation layer 75 is 4mm thick, the outer diameter of the air duct is 376mm, the inner diameter of the air duct is 360mm, and the radial thickness is 50mm.

[0078] refer to Figure 3 The six terminals 80 include a fourth terminal 80, a second terminal 80 disposed on the left side of the fourth terminal 80, a sixth terminal 80 disposed on the right side of the fourth terminal 80, a fifth terminal 80 disposed below the fourth terminal 80, a third terminal 80 disposed on the left side of the fifth terminal 80, and a seventh terminal 80 disposed on the right side of the fifth terminal 80.

[0079] The number of turns between the sixth terminal 80 and the fourth terminal 80 is 15 turns, the number of turns between the fourth terminal 80 and the second terminal 80 is 16 turns, the number of turns between the third terminal 80 and the fifth terminal 80 is 15 turns, the number of turns between the fifth terminal 80 and the seventh terminal 80 is 15 turns, the number of turns between the outgoing terminal 81 and the sixth terminal 80 is 288 turns (half of the remaining total turns), and the number of turns between the seventh terminal 80 and the incoming terminal 79 is 288 turns (half of the remaining total turns).

[0080] refer to Figure 7 and Figure 8 The low-voltage coil 54 passes through a low-voltage coil mold for winding the low-voltage coil and a low-voltage coil winding machine for rotating the low-voltage coil mold. By using the low-voltage coil winding machine, several layers of second insulating layers are wound on the low-voltage coil mold, and a layer of polypropylene film coating is applied on the contact surface between the low-voltage coil mold and the second insulating layer.

[0081] The low-voltage coil 54 includes a low-voltage coil body, a second insulating layer of several layers arranged in the low-voltage coil body, a plurality of pull-out pieces 83 arranged at intervals in the second insulating layer, a second air duct 88 formed by the pull-out piece 83 and the second insulating layer, two copper bars arranged at intervals in the second insulating layer, and a copper foil 86 arranged on the copper bar. The second insulating layer includes an inner second insulating layer 91, an outer second insulating layer 92, an interlayer second insulating layer and a reinforced second insulating layer 94 wound to form an inner second insulating layer 91 and an outer second insulating layer 92. A reinforced second insulating layer 94 is respectively provided at the starting end and the end between the copper bar and the inner second insulating layer 91. The copper bar includes an inner copper bar 85 and an outer copper bar 84. A plurality of turns of copper foil 86 and the inner copper bar 85 are arranged on the inner second insulating layer 91, a plurality of turns of copper foil 86 are arranged on the interlayer second insulating layer, and a plurality of turns of copper foil 86 and the outer copper bar 84 are arranged on the outer second insulating layer 92.

[0082] Six connecting terminals 80 are connected to the second and third layers of winding wires 72. After the welding of the wires and the terminals is completed, all carbon black is removed and the welding points are polished to leave no sharp corners. The segment spacing between the winding wires 72 is 11:26:11, and the number of turns of the six connecting terminals 80 is 16:15:15:15. The incoming terminal 79, the outgoing terminal 81, and the connecting terminal 80 are positioned and installed on the outgoing panel 78 on the boss.

[0083] The low-voltage coil 54 and the high-voltage coil 36 have good insulation performance and are easy to demold by setting the first air duct 76, the second air duct 88, the first insulating layer, and the second insulating layer. The electric field strength between the layers and the segments is reduced, making it easy to control the partial discharge and other properties of the transformer. The process winding method is simple and easy to dissipate heat. The high-voltage coil 36 is not easy to crack, the coil works more stably, and the maintenance cost of the transformer is reduced.

[0084] The dry-type transformer adopts the following production process, and the production process steps include

[0085] Step 1: Winding the high voltage coil 36;

[0086] Step 2: Winding the low voltage coil 54;

[0087] Step 3: Assemble the high voltage coil 36 of step 1, the low voltage coil 54 of step 2, the iron core 25, the base 21, the upper clamp 22, the lower clamp 31, the body insulation and the hardware connectors;

[0088] In this embodiment, step 1 may specifically consist of the following steps in sequence:

[0089] Step 1a, installing the high-voltage coil mold on the high-voltage coil winding machine for rotation, and preparing the high-voltage coil mold process;

[0090] Step 1b, winding the winding wire 72 and the first insulating layer on the high-voltage coil mold and inserting a plurality of airway rods arranged at intervals, connecting the winding wire 72 to the terminal, brushing a layer of release agent (release agent: polyorganosiloxane with a highly cross-linked network structure of silicone resin, with thermal stability) between the first insulating layer and the high-voltage coil 36, and performing the first coil winding process to finally obtain the first coil;

[0091] Step 1c, sending the first coil of step 1b into a curing drying oven for drying at a temperature of 120 to 140 degrees Celsius, preferably 130 degrees Celsius, and keeping warm for 9 to 12 hours, preferably 10 hours;

[0092] Step 1d, sending the first coil dried in step 1c into a resin casting machine for a casting process;

[0093] In this implementation, step 1d may specifically be:

[0094] Pouring process: feeding epoxy resin and curing agent into a mixing tank in a weight ratio of 1:1, preferably the epoxy resin is bisphenol A epoxy resin, and the curing agent is isomerized methyltetrahydrophthalic anhydride; heating to 70-80 degrees Celsius, preferably 80 degrees Celsius, vacuuming and stirring for 1.5-2 hours, preferably 2 hours, to obtain a mixture A, feeding the mixture A into a vacuum tank through a discharge valve to cast the first coil, and after the first coil of wire is filled, the following steps are adopted:

[0095] Step 1d1, evacuate the vacuum tank and let it stand for 25 to 45 minutes, preferably 30 minutes;

[0096] Step 1d2, breaking the vacuum state in the vacuum tank, then inflating and pressurizing to 2-3 kPa, preferably 3 kPa, and maintaining the pressure for 20 minutes;

[0097] Step 1d3, evacuate the vacuum tank and let it stand for 20 to 30 minutes, preferably 20 minutes;

[0098] Step 1d4, breaking the vacuum state in the vacuum tank, then inflating and pressurizing to 2-3 kPa, preferably 2 kPa, and maintaining the pressure for 20-30 minutes;

[0099] Step 1d5, adjust the pressure to 1 kPa, and let stand for 30 to 60 minutes, preferably 60 minutes.

[0100] Step 1e, sending the first coil cast in step 1d into a curing and drying oven for a curing and drying process;

[0101] Step 1f, demoulding and cooling the first coil in step 1e;

[0102] Step 1g, grinding and trimming the outer surface of the high-voltage coil 36 obtained in step 1f so that its end is flat and smooth, and performing a trimming process to obtain the high-voltage coil 36;

[0103] Step 1h. After the pouring in step 1d is completed, the mixing tank of the resin pouring machine is cleaned, and alcohol is used as a cleaning agent. During cleaning, the cleaning agent is automatically drawn into the mixing tank by a pipeline. During cleaning, the mixing tank is in a sealed state. After the cleaning is completed, the cleaning agent is discharged from the mixing tank through the waste liquid port, and the discharged and collected cleaning waste liquid is obtained. The cleaning waste liquid is allowed to stand to obtain a supernatant of alcohol and a precipitate of resin. The supernatant can be reused for cleaning the mixing tank to perform the cleaning process.

[0104] In the present embodiment, the curing and drying process in step 1e can be specifically carried out by curing and drying in a curing drying oven at a temperature of 80 to 140 degrees Celsius, including the following four stages in sequence: (1) the temperature of the first stage is 80 to 95 degrees Celsius, preferably 80 degrees Celsius, and the temperature is maintained for 3 to 5 hours, preferably 4 hours; (2) the temperature of the second stage is 100 to 110 degrees Celsius, preferably 110 degrees Celsius, and the temperature is maintained for 2 to 3 hours, preferably 3 hours; (3) the temperature of the third stage is 120 to 140 degrees Celsius, preferably 130 degrees Celsius, and the temperature is maintained for 3 to 5 hours, preferably 4 hours; (4) the temperature of the fourth stage is cooled to 90 to 110 degrees Celsius, preferably 100 degrees Celsius, and the temperature is maintained for 2 to 3 hours, preferably 2 hours.

[0105] The cross-section of the airway rod is rectangular, 25mm long and 8mm wide. The lateral dimensions of the straight parts of the upper and lower positioning circles of the high-voltage coil 36 are enlarged by 2mm on one side. The lower end plate hole on the high-voltage coil mold is a 9X25.5mm through hole, the upper end plate hole is a 10X27mm through hole, the central axis opening is 40.5X40.5mm, the casting bottom plate leg height is 90mm, the welding position is greater than or equal to 20mm from the outside, the inner membrane of the high-voltage coil mold adopts a tapered hard mold and is the same height as the outer mold. The outer mold is made according to the size of the positioning plate, and the upper and lower end plates are aligned with the airway rod holes.

[0106] The winding wire 72 of the high-voltage coil 36 is wound in a wave-shaped manner, with four sections and a total of eleven layers. The section spacing between the winding wires 72 is 11:26:11. During the winding process, the cylindrical surface of the same layer should be flat. The starting turn and the last turn of each layer in the winding wire 72 are bound with several layers of insulating cloth (the insulating cloth is an alkali-free and wax-free insulating tape bound at more than four points). The winding wire 72 is a segmented cylindrical type, and the winding wire 72 is wound in the right direction. The upper and lower ends of the inner first insulating layer and the outer first insulating layer 75 are higher than the winding wire 72, and the height dimension is 20 mm.

[0107] Six connecting terminals 80 are connected to the second and third layers of winding wires 72. After the wires and the terminals are welded, all carbon black is removed and the welding points are polished to remove sharp edges. Specifically, the incoming terminal 79, the outgoing terminal 81, and the connecting terminal 80 are positioned and installed on the outgoing panel 78 on the boss.

[0108] In this embodiment, step 2 can specifically be composed of the following steps in sequence:

[0109] Step 2a, installing the low-voltage coil 54 mold on a foil winding machine (foil winding machine model RJB1400) for rotation, preparing the low-voltage coil mold process;

[0110] Step 2b, winding the second insulating layer and the copper foil 86 on the low-voltage coil 54 mold, installing two copper bars arranged at intervals, a plurality of lead pieces arranged at intervals, and a temperature control probe tube 87 tied to a lead piece (the outer surface of the temperature control probe tube 87 is wrapped with a 3240 epoxy tube and the second insulating layer at the end is tied together with a lead piece 83 and installed in the second air duct 88), and performing the second coil winding process to obtain the second coil;

[0111] Step 2c, placing the second coil obtained in step 2b into a drying oven at a temperature of 120 to 140 degrees Celsius, preferably 130 degrees Celsius, for 9 to 11 hours, preferably 10 hours, to perform a second coil drying process;

[0112] Step 2d, taking out the second coil processed in step 2c, performing a terminal sealing process using room temperature epoxy resin, and standing for 2 hours to cool;

[0113] Step 2e: remove the low-voltage coil 54 mold from the second coil after the end-capping process, and perform a demoulding process to obtain the low-voltage coil 54.

[0114] In step 3, the core 25 is assembled in the following steps:

[0115] Step 3a, performing a longitudinal shearing process on the core raw material;

[0116] Step 3b, performing a transverse shearing process on the core material that has undergone the longitudinal shearing process in step 3a;

[0117] Step 3d, stacking the core material after the cross-cutting process in step 3b;

[0118] Step 3e, sealing the stacked iron core 25 raw material in step 3d to obtain the iron core 25;

[0119] In step 3e, the core 25 material is sealed: a room temperature epoxy resin coating is applied to the end of the core 25 and allowed to stand for 2 hours to solidify;

[0120] In step 1b, winding wire 72: the electromagnetic wire is wound, and the wound electromagnetic wire is arranged and pre-pressed, and then wrapped with insulating tape to obtain winding wire 72, and epoxy resin mixture is injected to penetrate between each layer of the winding, and the winding is cured and formed, so that the electromagnetic wire and the second insulating layer are combined into one to obtain winding wire 72; the insulating tape is preferably a Mara tape.

[0121] The low voltage coil 54 is a foil wound structure, with a left winding direction, and the copper foil 86 is wound on the low voltage coil 54 mold for a total of 14 turns, including the following steps:

[0122] (1) First, wind 4 turns (for the inner copper foil 86, connected to the inner conductive bar, the inner copper foil 86 has a thickness of 5.75 mm) and place several lead-out pieces at intervals;

[0123] Then, 4 turns are wound (the middle copper foil 86 has a radial thickness of 5.75 mm) and a plurality of lead pieces are placed at intervals;

[0124] Finally, the remaining 6 turns (which are the outer copper foil 86 connected to the outer conductive bar, and the outer copper foil 86 has a radial thickness of 8.5 mm) are wound.

[0125] The second insulating layer includes an inner second insulating layer wound on the low voltage coil 54 mold, an interlayer second insulating layer wound on both sides of the middle copper foil 86, and an outer insulating layer and a reinforced second insulating layer wound on the outer side of the outer copper foil 86.

[0126] The outer surface of the low-voltage coil 54 is wrapped with three layers of the second insulating layer (preferably pre-impregnated MDM with a thickness of 0.2 mm) and then wrapped with one layer of half-folded heat shrink tape. A reinforced second insulating layer is respectively provided on the starting end and the tail end between the copper bar and the inner second insulating layer. A reinforced second insulating layer is padded between the lead row and adjacent turns in the low-voltage coil 54. The lower ends of the two lead rows in the low-voltage coil 54 are flush with the copper foil 86, and the upper and lower ends of the second insulating layer are higher than the low-voltage copper foil 86 by 15 to 20 mm.

[0127] The foil winding structure is adopted to improve the space utilization rate in the low-voltage coil 54, so that the iron core 2525 is distributed symmetrically, the electric field distribution is more uniform, the structure is more compact, and the manufacturing is simple and easy to use.

[0128] A second reinforcing insulating layer 94 (the reinforcing second insulating layer 94 is a two-layer pre-impregnated DMD) is added between the lead row and the adjacent turns in the low-voltage coil 54 to increase the insulation effect at the start and end of the copper row. The lower ends of the two lead rows in the low-voltage coil 54 are flush with the copper foil 86, and the upper and lower ends of the second insulating layer are 15 to 20 mm higher than the copper foil 86. The inner diameter of the low-voltage coil 54 is 194 mm, and the outer diameter of the low-voltage coil 54 is 266 mm. The epoxy resin can be 8855A / B epoxy resin with fillers

[0129] Example 2, refer to Figure 1 The difference between the second embodiment and the first embodiment is that in step 1d, the raw materials used in the casting process include epoxy resin, curing agent and plasticizer.

[0130] Pouring process: epoxy resin, curing agent and plasticizer are fed into a mixing tank at a weight ratio of 1:1:0.5. The preferred epoxy resin is bisphenol A epoxy resin, and the curing agent is isomerized methyltetrahydrophthalic anhydride; plasticizer: side chain epoxy resin, the effect of which is to prevent the high-voltage coil 36 from cracking, heated to 70 to 80 degrees Celsius, preferably 80 degrees Celsius, vacuumed and stirred for 1.5 to 3 hours, preferably 3 hours, to obtain a mixture B, and the mixture B is fed into a vacuum tank through a discharge valve to cast the first coil. The other structures are similar to those in Example 1 and will not be repeated here.

[0131] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A dry-type transformer, comprising a base, an iron core mounted on the base, three high- and low-voltage coil groups respectively sleeved on the three iron cores, a body insulation member provided on the high- and low-voltage coil groups, and a hardware connector for connecting the high- and low-voltage coil groups and the iron core, characterized in that: The high-voltage coil is manufactured by a high-voltage coil mold for winding the high-voltage coil, a high-voltage coil winding machine for rotating the high-voltage coil mold, a resin pouring machine for pouring the high-voltage coil mold, and a pair of curing and drying ovens for curing and drying the high-voltage coil mold. The high-voltage coil includes a first insulating layer composed of several layers wound by the high-voltage coil winding machine, a winding wire wound by the high-voltage coil winding machine in the first insulating layer, several first air ducts arranged at intervals in the first insulating layer, and six first air ducts connected to the winding wire through tap leads. The connected terminals, the distance between adjacent tap leads is 15 to 20 mm, the distance between the tap leads and the unconnected terminals is ≥10 mm, the number of turns of the tap leads is 16:15:15:15, and the first insulating layer includes an inner first insulating layer wound by the high-voltage coil mold, an interlayer first insulating layer wound on one side of the inner first insulating layer, an outer first insulating layer wound on the other side of the interlayer first insulating layer, and an air duct insulation layer wound on the first air duct, and the distance between the tap lead and the outermost layer of the first insulating layer is 15 to 20 mm.

2. A dry-type transformer as claimed in claim 1, characterized in that: The portion of the inner interlayer insulation of the high-voltage coil that exceeds the conductor is covered with an insulating tape.

3. A dry-type transformer as claimed in claim 1, characterized in that: The low-voltage coil is manufactured by a low-voltage coil mold for winding the low-voltage coil and a low-voltage coil winding machine for rotating the low-voltage coil mold. Several layers of second insulating layers are wound on the low-voltage coil mold by using the low-voltage coil winding machine, and a layer of polypropylene film coating is applied on the contact surface between the low-voltage coil mold and the second insulating layer.

4. A dry-type transformer production process, characterized in that: The production process is used to produce the dry-type transformer described in any one of claims 1 to 3, and the production process steps include: Step 1: Winding the high voltage coil; Step 2: Winding the low voltage coil; Step 3: Assemble the high-voltage coil of step 1, the low-voltage coil of step 2, the iron core, the base, the upper clamp, the lower clamp, the body insulation parts and the hardware connectors.

5. A dry-type transformer production process as claimed in claim 4, characterized in that: The step 1 is composed of the following steps in sequence: Step 1a, installing the high-voltage coil mold on the high-voltage coil winding machine for rotation, and preparing the high-voltage coil mold process; Step 1b, winding the winding wire and the first insulating layer on the high-voltage coil mold and inserting a plurality of airway rods arranged at intervals, connecting the winding wire to the terminal, applying a layer of mold release agent between the first insulating layer and the high-voltage coil, and performing the first coil winding process to finally obtain the first coil; Step 1c, sending the first coil of step 1b into a curing drying oven for drying at a temperature of 120 to 140 degrees Celsius for 9 to 12 hours; Step 1d, sending the first coil dried in step 1c into a resin casting machine for a casting process; Step 1e, sending the first coil cast in step 1d into a curing and drying oven for a curing and drying process; Step 1f, demoulding and cooling the first coil in step 1e; Step 1g, grinding and trimming the outer surface of the high-voltage coil obtained in step 1f to make its end flat and smooth, and performing a trimming process to obtain a high-voltage coil; Step 1h. After the pouring in step 1d is completed, the mixing tank of the resin pouring machine is cleaned, and alcohol is used as a cleaning agent. During the cleaning, the cleaning agent is automatically drawn into the mixing tank by a pipeline. During the cleaning, the mixing tank is in a sealed state. After the cleaning is completed, the cleaning agent is discharged from the mixing tank through the waste liquid port, and the discharged and collected cleaning waste liquid is obtained. The cleaning waste liquid is allowed to stand to obtain a supernatant of alcohol and a precipitate of resin. The supernatant can be reused for cleaning the mixing tank to perform a cleaning process. The step 2 is composed of the following steps in sequence: Step 2a, installing the low-voltage coil mold on the foil winding machine for rotation, and preparing the low-voltage coil mold process; Step 2b, winding the second insulating layer and the copper foil on the low-voltage coil mold, installing two copper bars arranged at intervals, a plurality of lead pieces arranged at intervals and a temperature control probe tube tied to a lead piece, and performing a second coil winding process to obtain a second coil; Step 2c, placing the second coil obtained in step 2b into a drying oven at a temperature of 120 to 140 degrees Celsius for 9 to 11 hours to perform a drying process for the second coil; Step 2d, taking out the second coil processed in step 2c, performing a terminal sealing process using room temperature epoxy resin, and standing for 2 hours to cool; Step 2e: After the end-sealing process, the low-voltage coil mold is removed from the second coil, and a demoulding process is performed to obtain a low-voltage coil.

6. A dry-type transformer production process as claimed in claim 5, characterized in that: In step 1d, Pouring process: Add epoxy resin and curing agent into the mixing tank in a weight ratio of 1:1, heat to 70-80 degrees Celsius, vacuum and stir for 1.5-2 hours to obtain mixture A, and send mixture A into the vacuum tank through the discharge valve to pour the first coil. After the first coil of wire is filled, the following steps are adopted: Step 1d1, evacuate the vacuum tank and let it stand for 25 to 45 minutes; Step 1d2, breaking the vacuum state in the vacuum tank, then inflating and pressurizing to 2-3 kPa, and maintaining the pressure for 20 minutes; Step 1d3, evacuate the vacuum tank and let it stand for 20 to 30 minutes; Step 1d4, breaking the vacuum state in the vacuum tank, then inflating and pressurizing it to 2-3 kPa, maintaining the pressure for 20-30 minutes; Step 1d5, adjust the pressure to 1 kPa and let it stand for 30 to 60 minutes.

7. A dry-type transformer production process as claimed in claim 5, characterized in that: In step 1e, the curing and drying process is carried out in a curing drying oven at a temperature of 80 to 140 degrees Celsius, and includes the following four stages in sequence: (1) the temperature of the first stage is 80 to 95 degrees Celsius, and the temperature is maintained for 3 to 5 hours; (2) the temperature of the second stage is 100 to 110 degrees Celsius, and the temperature is maintained for 2 to 3 hours; (3) the temperature of the third stage is 120 to 140 degrees Celsius, and the temperature is maintained for 3 to 5 hours; (4) the temperature of the fourth stage is cooled to 90 to 110 degrees Celsius, and the temperature is maintained for 2 to 3 hours.

8. A dry-type transformer production process as claimed in claim 5, characterized in that: In step 3, the core is assembled in the following steps: Step 3a, performing a longitudinal shearing process on the core raw material; Step 3b, performing a transverse shearing process on the core material that has undergone the longitudinal shearing process in step 3a; Step 3d, stacking the core material after the cross-cutting process in step 3b; Step 3e, sealing the core raw material after the stacking process in step 3d to obtain the core; In step 3e, the core material is sealed: a room temperature epoxy resin coating is applied to the end of the core, and the coating is left to stand for 2 hours to solidify; In step 1b, winding wire: the electromagnetic wire is wound, the electromagnetic wire is arranged and pre-pressed, and then the electromagnetic wire is wrapped with insulating tape to obtain the winding wire, and the epoxy resin mixture is injected to penetrate between the layers of the winding, and the winding is cured and formed, so that the electromagnetic wire and the second insulating layer are combined into one to obtain the winding wire.

9. A dry-type transformer production process as claimed in claim 5, characterized in that: The copper foil is wound on the low-voltage coil mold for 14 turns in total, including the following steps: (1) first winding 4 turns and placing a number of lead-out pieces at intervals, (2) winding 4 turns again and placing a number of lead-out pieces at intervals, and (3) finally winding the remaining 6 turns. The second insulation layer includes an inner second insulation layer wound on the low-voltage coil mold, an interlayer second insulation layer wound on both sides of the middle copper foil, an outer insulation layer and a reinforced second insulation layer wound on the outer side of the outer copper foil. The outer surface of the low-voltage coil is wrapped with three layers of the second insulation layer and then wrapped with a half-folded layer of heat-shrinkable tape. The starting end and the end end between the copper bar and the inner second insulation layer are respectively provided with a reinforced second insulation layer. The reinforced second insulation layer is padded between the lead bar and the adjacent turns in the low-voltage coil. The lower ends of the two lead bars in the low-voltage coil are flush with the copper foil, and the upper and lower ends of the second insulation layer are 15 to 20 mm higher than the low-voltage copper foil.

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