CN118263000A - High-heat-conductivity encapsulation layer of dry type air-core reactor and preparation method thereof - Google Patents

Abstract

The invention provides a high heat conduction encapsulating layer of a dry type air-core reactor, which comprises the following components: the fiber bundle flat winding layer and the fiber bundle flower winding layer are overlapped and bonded through the high-heat-conductivity epoxy material; wherein the fiber bundle flower winding layer is in contact with the coil of the reactor. The invention also provides a preparation method of the high-heat-conductivity encapsulation layer of the dry-type air-core reactor. According to the invention, the low-viscosity liquid epoxy resin with a high epoxy value is selected, and the active toughening agent with a dilution effect is matched, so that the viscosity of the high-heat-conductivity epoxy material is further reduced, the high filling rate of the inorganic heat-conductivity filler and the rapid infiltration with the fiber bundles are realized, and the heat conductivity of the encapsulation layer is improved; according to the invention, the viscosity of the high-heat-conductivity epoxy material is further reduced by adopting the acid anhydride curing agent, so that the high-uniformity distribution and filling of the inorganic heat-conductivity filler in the winding process are realized; the toughness of the cured product is improved, the cracking resistance of the dry-type air-core reactor encapsulation layer is improved, and the stability of the insulation performance is ensured.

Description

A high thermal conductivity encapsulation layer for dry-type air-core reactor and preparation method thereof

Technical Field

The invention belongs to the technical field of electrical insulation materials, and in particular relates to a high thermal conductivity encapsulation layer of a dry-type air-core reactor and a preparation method thereof.

Background technique

Wire winding encapsulation is one of the key structures in dry-type air-core reactors. It is usually formed by wet winding of untwisted glass fiber and liquid epoxy composition, which plays an important role in fixing wire winding, protection and insulation. Insulation material is one of the key factors restricting the further improvement of safety, stability and service life of power equipment. The main reason for the failure of insulation material is the long-term high temperature operating environment of electrical equipment. Reducing the temperature rise of equipment is extremely critical to extending the service life of equipment.

The encapsulation layer of the traditional dry-type air-core reactor is made of conventional FRP material, that is, a composite material of glass fiber and epoxy resin, with a thermal conductivity of about 0.4W/m·K. Under the existing material system, there is very limited room for reducing the temperature rise or reducing the cost of the equipment by design without increasing the volume of the equipment. However, the thermal conductivity of the existing encapsulation layer hinders the improvement of the heat dissipation performance of electrical equipment.

Summary of the invention

The object of the present invention is to increase the thermal conductivity of the encapsulation layer.

The purpose of the present invention is to adopt the following technical solutions to achieve:

A high thermal conductivity encapsulation layer for a dry-type air-core reactor, the encapsulation layer comprising: a fiber bundle flat winding layer and a fiber bundle flower winding layer overlapped and bonded by a high thermal conductivity epoxy material; wherein the fiber bundle flower winding layer is in contact with a coil of the reactor.

Preferably, the high thermal conductivity epoxy material comprises: 100 parts of epoxy resin, 80-100 parts of curing agent, 0.2-1.5 parts of accelerator, 300-465 parts of inorganic thermal conductive filler, and 8-15 parts of toughening agent.

Preferably, the epoxy resin includes one or more combinations of bisphenol A epoxy resin and diglycidyl hexahydrophthalate.

Preferably, the curing agent is one or a combination of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and polyamide resin.

Preferably, the preparation process of the high thermal conductivity epoxy material comprises the following steps: preheating the epoxy resin, curing agent, accelerator, inorganic thermal conductive filler and toughening agent to the same temperature respectively; adding the preheated raw materials into a mixing container and stirring evenly under a constant temperature vacuum environment to obtain the high thermal conductivity epoxy material.

Preferably, the bisphenol A epoxy resin has an epoxy value of 0.55-0.58.

Preferably, the amine value of the polyamide resin is 180-300.

Preferably, the inorganic thermal conductive filler includes one or a combination of Al ₂ O ₃ , ZnO, AlN, and SiC.

Preferably, the Al2O3 comprises amorphous α- _{Al2O3 that} has been subjected to surface activation treatment.

Preferably, the median diameter of the amorphous α-Al ₂ O ₃ is 5-30 μm.

Preferably, the toughening agent includes polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, polypropylene glycol, and polymers containing hydroxyl groups, ester groups, and ether groups.

Preferably, the molecular weight of the polypropylene glycol diglycidyl ether is 288-462.

Preferably, the fiber bundles used in the fiber bundle flat winding layer and the fiber bundle flower winding layer are alkali-free untwisted glass fiber bundles.

Preferably, the linear density of the alkali-free untwisted glass fiber bundle is 1200-4800 Tex.

Based on the same inventive concept, the present invention also provides a method for preparing a high thermal conductivity encapsulation layer of a dry-type air-core reactor, which is used for preparing the high thermal conductivity encapsulation layer of the dry-type air-core reactor. The preparation method comprises the following steps:

S1: Pulling the fiber bundle through the liquid high thermal conductivity epoxy material continuously by a pulling device to obtain the impregnated fiber bundle;

S2: Arranging the dipped fiber bundle into a fiber tape through a yarn arrangement device;

S3: Winding the fiber tape in a spiral manner with a spacing smaller than the width of the fiber tape on the surface of the coil of the reactor to form a fiber bundle flat winding layer;

S4: reciprocatingly winding the fiber tape on the surface of the fiber bundle flat winding layer from one end to the other end in a spiral manner with a spacing greater than the width of the fiber tape to form a fiber bundle flower winding layer;

S5: placing the reactor after completing steps S4 and S5 in a curing furnace for curing to obtain the high thermal conductivity encapsulation layer of the dry-type air-core reactor.

Preferably, the preparation method comprises multiple alternating cycles of steps S3 and S4.

Preferably, the step S3 or S4 includes winding a plurality of fiber tapes simultaneously.

Preferably, the overlap width of the fiber tapes of the flat-wound layer of the fiber bundle is within a range of 10-20 mm.

Preferably, the fiber bundle winding layer has a winding pitch of 250-350 mm.

Preferably, the fiber bundle winding layer has a winding grid spacing of 30-80 mm.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention further reduces the viscosity of the high thermal conductivity epoxy material by selecting a low-viscosity liquid epoxy resin with a high epoxy value and a diluting active toughening agent, thereby achieving a high filling rate of the inorganic thermal conductive filler and rapid infiltration with the fiber bundle, thereby improving the thermal conductivity of the encapsulation layer;

2. The present invention further reduces the viscosity of the high thermal conductivity epoxy material by using anhydride curing agent, thereby achieving high uniformity distribution and filling of the inorganic thermal conductive filler in the winding process; at the same time, the anhydride curing agent significantly extends the operability period of the system, further improves the toughness of the cured product while ensuring sufficient mechanical strength, improves the anti-cracking performance of the dry-type air-core reactor encapsulation layer, ensures the stability of the insulation performance, and provides an important guarantee for the long-term stable operation of the dry-type air-core reactor;

3. The present invention uses surface activation to treat micron-sized α-Al ₂ O ₃ , thereby enhancing the interface bonding with epoxy, reducing the interface thermal resistance between particles and epoxy, and improving its anti-settling ability, arc resistance and flame retardancy. Compared with spherical alumina, amorphous particles can increase the filling rate and significantly reduce material costs; the high filling of Al ₂ O ₃ particles greatly improves the thermal conductivity of the encapsulation layer, reduces the aging speed of the insulation layer, and achieves the beneficial technical effect of significantly extending the service life of the equipment;

4. The fiber bundle flat winding layer in the encapsulation layer disclosed in the present invention provides radial binding force for the transposed aluminum conductor, and the fiber bundle flower winding layer mainly provides axial binding force. The combination of the two winding forms realizes the fixation of large-size coils at each layer of the air-core reactor. At the same time, the dense fiber bundle flat winding layer plays a major role in isolating the coil from the environment, avoiding the insulation failure problem caused by water vapor entering the coil from the environment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the unfolding of a flat-wound layer of a fiber bundle of the present invention;

FIG2 is a schematic diagram of the fiber bundle winding layer unfolding of the present invention;

Wherein: 1-fiber tape; 2-coil; 3-fiber tape overlap width; 4-grid spacing; 5-fiber tape width.

Detailed ways

The technical solution is further described below in conjunction with the accompanying drawings and specific embodiments to help understand the content of the present invention.

Example 1

The invention discloses a high thermal conductivity encapsulation layer of a dry-type air-core reactor, wherein the encapsulation layer comprises: a fiber bundle flat winding layer and a fiber bundle flower winding layer overlapped and bonded by a high thermal conductivity epoxy material; wherein the fiber bundle flower winding layer is in contact with a coil of the reactor.

The high thermal conductivity epoxy material comprises: 100 parts of epoxy resin, 80-100 parts of curing agent, 0.2-1.5 parts of accelerator, 300-465 parts of inorganic thermal conductive filler, and 8-15 parts of toughening agent.

The epoxy resin includes one or more combinations of bisphenol A epoxy resin and diglycidyl hexahydrophthalate.

The curing agent is one or a combination of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and polyamide resin.

The preparation process of the high thermal conductivity epoxy material includes the following steps: preheating the epoxy resin, curing agent, accelerator, inorganic thermal conductive filler and toughening agent to the same temperature respectively; adding the preheated raw materials into a mixing container and stirring them evenly under a constant temperature vacuum environment to obtain the high thermal conductivity epoxy material.

The epoxy value of the bisphenol A epoxy resin is 0.55-0.58.

The amine value of the polyamide resin is 180-300, and any intermediate value within the range can be selected, such as amine values of 190, 200, 210, 280, 290, etc.

The inorganic thermal conductive filler includes one or a combination of Al ₂ O ₃ , ZnO, AlN, and SiC; wherein ZnO has a particle size of 3-8 μm; AlN has a particle size of 1-12 μm; and SiC has a particle size of 10 μm.

_{The Al2O3} comprises _amorphous α- _Al2O3 after surface activation treatment. After the surface of the aluminum oxide raw powder is chemically etched, active groups capable of reacting with the epoxy system are grafted on the surface of the aluminum oxide by a chemical surface modification method, so that the epoxy matrix and the inorganic filler have better interface bonding and lower interface thermal resistance.

The median diameter of the amorphous α-Al ₂ O ₃ is 5-30 μm.

The toughening agent includes polypropylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, polypropylene glycol, and a polymer containing a hydroxyl group, an ester group, and an ether group.

The molecular weight of the polypropylene glycol diglycidyl ether is 288-462.

The fiber bundles used in the fiber bundle flat winding layer and the fiber bundle flower winding layer are alkali-free untwisted glass fiber bundles.

The linear density of the alkali-free untwisted glass fiber bundle is 1200-4800 Tex, and any intermediate value within this range can be selected according to strength requirements, such as 1300, 1400, 1500, 1600, ..., 3000, ..., 4500, 4600, 4700 and the like.

After the surface of the alumina raw powder is chemically etched, the active groups that can react with the epoxy system are grafted onto the surface of the alumina through a chemical surface modification method, so that the epoxy matrix and the inorganic filler have better interface bonding and lower interface thermal resistance.

(1) 100 g of bisphenol A epoxy resin with an epoxy value of 0.58, 93 g of methyltetrahydrophthalic anhydride, 0.8 g of dimethylbenzylamine, 10 g of polypropylene glycol diglycidyl ether, and 425 g of alumina particles were preheated at 50° C. for 4 h, then added to a final mixing tank, stirred at 50° C. and a vacuum degree of 300 Pa for 2 h to obtain a high thermal conductivity epoxy material, and the high thermal conductivity epoxy material was added to a thermostatic glue tank of a winding equipment, and the temperature of the thermostatic glue tank was 60° C.

(2) The dipping and winding reel provides traction force, and the 4400Tex glass fiber bundle is dipping and winding the fiber for use through the warp frame, guide rollers, dipping tank, scraper plate and other structures. Through this process, the weight content of the dipping fiber is controlled at 60%-65%.

(3) Place 5 rolls of spare dipped fiber discs on the dipped yarn rack, and lead out 5 bundles of fibers respectively through the yarn arrangement, guide roller, and yarn winding arm for fiber winding and encapsulation.

(4) The high thermal conductivity encapsulation layer of the dry-type air-core reactor is composed of a layer of fiber bundle flat winding layer and a layer of fiber bundle flower winding layer, wherein the flower winding layer is in contact with the coil. Production of the flat winding layer: As shown in FIG1, a fiber band 1 composed of 5 fiber bundles is wound on the surface of the coil 2 of the dry-type air-core reactor from one end to the other end in a spiral manner with a spacing less than the width of the fiber band, forming a fiber bundle flat winding layer, forming a fiber band flat overlapped winding, and the fiber band overlap width 3 is 20 mm; Production of the flower winding layer: As shown in FIG2, a fiber band composed of 5 fiber bundles is wound back and forth from one end to the other end in a spiral manner with a spacing greater than the width of the fiber band 5 on the outside of the coil of the dry-type air-core reactor, forming a fiber bundle flower winding layer, the flower winding pitch is 280 mm, and it is wound back and forth from one end to the other end, and the grid spacing 4 of the fiber bundle flower winding layer is 40 mm.

(5) After several encapsulation windings are completed, the encapsulation is placed in a curing furnace for curing to obtain a high thermal conductivity encapsulation layer of a dry-type air-core reactor.

The present invention further reduces the viscosity of the high thermal conductivity epoxy material by selecting a low-viscosity liquid epoxy resin with a high epoxy value and combining it with an active toughening agent with a diluting effect, thereby achieving a high filling rate of the inorganic thermal conductive filler and rapid infiltration with the fiber bundle, thereby improving the thermal conductivity of the encapsulation layer;

The present invention further reduces the viscosity of the high thermal conductivity epoxy material by using an anhydride curing agent, thereby achieving high uniformity distribution and filling of the inorganic thermal conductive filler in the winding process; at the same time, the anhydride curing agent significantly prolongs the operability period of the system, further improves the toughness of the cured product while ensuring sufficient mechanical strength, improves the anti-cracking performance of the encapsulation layer of the dry-type air-core reactor, ensures the stability of the insulation performance, and provides an important guarantee for the long-term stable operation of the dry-type air-core reactor;

The present invention uses surface activation to treat micron-sized α-Al ₂ O ₃ , thereby enhancing the interface bonding with epoxy, reducing the interface thermal resistance between the particles and epoxy, and improving its anti-settling ability, arc resistance and flame retardancy. Compared with spherical alumina, amorphous particles can increase the filling rate and significantly reduce the material cost; the high filling of Al ₂ O ₃ particles greatly improves the thermal conductivity of the encapsulation layer, reduces the aging speed of the insulation layer, and achieves the beneficial technical effect of significantly extending the service life of the equipment;

The fiber bundle flat winding layer in the encapsulation layer disclosed in the present invention provides radial binding force for the transposed aluminum conductor, and the fiber bundle flower winding layer mainly provides axial binding force. The cooperation of the two winding forms realizes the fixation of large-size coils at each layer of the air-core reactor. At the same time, the dense fiber bundle flat winding layer plays a major role in isolating the coil from the environment, avoiding the insulation failure problem caused by water vapor entering the coil from the environment.

Example 2

Based on the same inventive concept, the present invention also provides a method for preparing a high thermal conductivity encapsulation layer of a dry-type air-core reactor, which is used for preparing the high thermal conductivity encapsulation layer of the dry-type air-core reactor. The preparation method comprises the following steps:

S1: Pulling the fiber bundle through the liquid high thermal conductivity epoxy material continuously by a pulling device to obtain the impregnated fiber bundle;

S2: Arranging the dipped fiber bundle into a fiber tape through a yarn arrangement device;

S3: Winding the fiber tape in a spiral manner with a spacing smaller than the width of the fiber tape on the surface of the coil of the reactor to form a fiber bundle flat winding layer;

S4: reciprocatingly winding the fiber tape on the surface of the fiber bundle flat winding layer from one end to the other end in a spiral manner with a spacing greater than the width of the fiber tape to form a fiber bundle flower winding layer;

S5: placing the reactor after completing steps S4 and S5 in a curing furnace for curing to obtain the high thermal conductivity encapsulation layer of the dry-type air-core reactor.

The preparation method comprises steps S3 and S4 which are repeated alternately for a plurality of times.

The step S3 or S4 includes winding a plurality of fiber tapes simultaneously.

The overlap width of the fiber tapes of the fiber bundle flat winding layer is within a range of 10-20 mm.

The fiber bundle winding layer has a winding pitch of 250-350 mm.

The fiber bundle winding layer has a winding grid spacing of 30-80 mm.

The specific implementation steps of the method for preparing a high thermal conductivity encapsulation layer of a dry-type air-core reactor are as follows:

(1) Preheat 100 g of hexahydrophthalic acid diglycidyl ester, 93 g of methyl hexahydrophthalic anhydride, 0.8 g of dimethylbenzylamine, 10 g of polypropylene glycol diglycidyl ether, and 425 g of alumina particles at 50° C. for 4 h, respectively, then add them to a final mixing tank, stir them at 50° C. and a vacuum degree of 300 Pa for 2 h to obtain a high thermal conductivity epoxy material, and add the high thermal conductivity epoxy material to a constant temperature glue tank of a winding equipment, wherein the temperature of the constant temperature glue tank is 60° C.

(2) The dipping and winding reel provides traction force, and the 4400Tex glass fiber bundle is dipping and winding the fiber for use through the warp frame, guide rollers, dipping tank, scraper plate and other structures. Through this process, the weight content of the dipping fiber is controlled at 60%-65%.

(3) Place 5 rolls of spare dipped fiber discs on the dipped yarn rack, and lead out 5 bundles of fibers respectively through the yarn arrangement, guide roller, and yarn winding arm for fiber winding and encapsulation.

(4) The high thermal conductivity encapsulation layer of the dry-type air-core reactor is composed of a layer of flat-wound fiber bundles and a layer of flower-wound fiber bundles, wherein the flower-wound fiber bundles are in contact with the coil. Production of the flat-wound fiber bundle: As shown in FIG1, a fiber band 1 composed of 5 fiber bundles is wound on the surface of the coil 2 of the dry-type air-core reactor from one end to the other end in a spiral manner with a spacing less than the width of the fiber band, forming a flat-wound fiber bundle layer, and the fiber band is wound in a flat overlapping manner, and the overlap width 3 of the fiber band is 10 mm; Production of the flower-wound fiber bundle: As shown in FIG2, a fiber band composed of 5 fiber bundles is wound back and forth from one end to the other end in a spiral manner with a spacing greater than the width 5 of the fiber band on the outside of the coil of the dry-type air-core reactor, forming a fiber bundle flower-wound fiber bundle layer, the flower-wound pitch is 250 mm, and the fiber bundle flower-wound fiber bundle layer is wound back and forth from one end to the other end in a spiral manner with a spacing greater than the width 5 of the fiber band. The mesh spacing 4 of the fiber bundle flower-wound fiber bundle layer is 30 mm.

(5) After several encapsulation windings are completed, the encapsulation is placed in a curing furnace for curing to obtain a high thermal conductivity encapsulation layer of a dry-type air-core reactor.

The technical contents and technical effects not mentioned are the same as those in Example 1, so they will not be repeated here.

Example 3

The invention discloses a high thermal conductivity encapsulation layer of a dry-type air-core reactor, wherein the encapsulation layer comprises: a fiber bundle flat winding layer and a fiber bundle flower winding layer overlapped and bonded by a high thermal conductivity epoxy material; wherein the fiber bundle flower winding layer is in contact with a coil of the reactor.

Based on the same inventive concept, the present invention also provides a method for preparing a high thermal conductivity encapsulation layer of a dry-type air-core reactor, which is used for preparing the high thermal conductivity encapsulation layer of the dry-type air-core reactor. The preparation method comprises the following steps:

S1: Pulling the fiber bundle through the liquid high thermal conductivity epoxy material continuously by a pulling device to obtain the impregnated fiber bundle;

S2: Arranging the dipped fiber bundle into a fiber tape through a yarn arrangement device;

S3: Winding the fiber tape in a spiral manner with a spacing smaller than the width of the fiber tape on the surface of the coil of the reactor to form a fiber bundle flat winding layer;

S4: reciprocatingly winding the fiber tape on the surface of the fiber bundle flat winding layer from one end to the other end in a spiral manner with a spacing greater than the width of the fiber tape to form a fiber bundle flower winding layer;

S5: placing the reactor after completing steps S4 and S5 in a curing furnace for curing to obtain the high thermal conductivity encapsulation layer of the dry-type air-core reactor.

The preparation method comprises steps S3 and S4 which are repeated alternately for a plurality of times.

The step S3 or S4 includes winding a plurality of fiber tapes simultaneously.

The overlap width of the fiber tapes of the fiber bundle flat winding layer is within a range of 10-20 mm.

The fiber bundle winding layer has a winding pitch of 250-350 mm.

The fiber bundle winding layer has a winding grid spacing of 30-80 mm.

The specific implementation steps of the method for preparing a high thermal conductivity encapsulation layer of a dry-type air-core reactor are as follows:

(1) Preheat 100 g of hexahydrophthalic acid diglycidyl ester, 77 g of methyl hexahydrophthalic anhydride, 15 g of polyamide resin, 0.5 g of dimethylbenzylamine, 10 g of polypropylene glycol diglycidyl ether, and 465 g of alumina particles at 50° C. for 4 h, add them to a final mixing tank, stir them at 50° C. and a vacuum degree of 300 Pa for 2 h to obtain a high thermal conductivity epoxy material, and add the high thermal conductivity epoxy material to a constant temperature glue tank of a winding equipment, wherein the temperature of the constant temperature glue tank is 60° C.

(2) The dipping and winding reel provides traction force, and the 4400Tex glass fiber bundle is dipping and winding the fiber for use through the warp frame, guide rollers, dipping tank, scraper plate and other structures. Through this process, the weight content of the dipping fiber is controlled at 60%-65%.

(3) Place 5 rolls of spare dipped fiber discs on the dipped yarn rack, and lead out 5 bundles of fibers respectively through the yarn arrangement, guide roller, and yarn winding arm for fiber winding and encapsulation.

(4) The high thermal conductivity encapsulation layer of the dry-type air-core reactor is composed of a layer of flat-wound fiber bundles and a layer of flower-wound fiber bundles, wherein the flower-wound fiber bundles are in contact with the coil. Production of the flat-wound fiber bundle: As shown in FIG1, a fiber band 1 composed of 5 fiber bundles is wound on the surface of the coil 2 of the dry-type air-core reactor from one end to the other end in a spiral manner with a spacing less than the width of the fiber band, forming a flat-wound fiber bundle layer, and the fiber band is wound in a flat overlapping manner, and the overlap width 3 of the fiber band is 15 mm; Production of the flower-wound fiber bundle: As shown in FIG2, a fiber band composed of 5 fiber bundles is wound back and forth from one end to the other end in a spiral manner with a spacing greater than the width 5 of the fiber band on the outside of the coil of the dry-type air-core reactor, forming a fiber bundle flower-wound fiber bundle layer, the flower-wound pitch is 300 mm, and the fiber bundle flower-wound fiber bundle layer is wound back and forth from one end to the other end in a spiral manner with a spacing greater than the width 5 of the fiber band, and the mesh spacing 4 of the fiber bundle flower-wound fiber bundle layer is 55 mm.

(5) After completing several encapsulation windings, the encapsulation is placed in a curing furnace for curing to obtain a high thermal conductivity encapsulation layer of a dry-type air-core reactor.

The technical contents and technical effects not mentioned are the same as those in Example 1, so they will not be repeated here.

Example 4

The invention discloses a high thermal conductivity encapsulation layer of a dry-type air-core reactor, wherein the encapsulation layer comprises: a fiber bundle flat winding layer and a fiber bundle flower winding layer overlapped and bonded by a high thermal conductivity epoxy material; wherein the fiber bundle flower winding layer is in contact with a coil of the reactor.

Based on the same inventive concept, the present invention also provides a method for preparing a high thermal conductivity encapsulation layer of a dry-type air-core reactor, which is used for preparing the high thermal conductivity encapsulation layer of the dry-type air-core reactor. The preparation method comprises the following steps:

S1: Pulling the fiber bundle through the liquid high thermal conductivity epoxy material continuously by a pulling device to obtain the impregnated fiber bundle;

S2: Arranging the dipped fiber bundle into a fiber tape through a yarn arrangement device;

S3: Winding the fiber tape in a spiral manner with a spacing smaller than the width of the fiber tape on the surface of the coil of the reactor to form a fiber bundle flat winding layer;

S4: reciprocatingly winding the fiber tape on the surface of the fiber bundle flat winding layer from one end to the other end in a spiral manner with a spacing greater than the width of the fiber tape to form a fiber bundle flower winding layer;

S5: placing the reactor after completing steps S4 and S5 in a curing furnace for curing to obtain the high thermal conductivity encapsulation layer of the dry-type air-core reactor.

The preparation method comprises steps S3 and S4 which are repeated alternately for a plurality of times.

The step S3 or S4 includes winding a plurality of fiber tapes simultaneously.

The overlap width of the fiber tapes of the fiber bundle flat winding layer is within a range of 10-20 mm.

The fiber bundle winding layer has a winding pitch of 250-350 mm.

The fiber bundle winding layer has a winding grid spacing of 30-80 mm.

The specific implementation steps of the method for preparing a high thermal conductivity encapsulation layer of a dry-type air-core reactor are as follows:

(1) Preheat 67 g of bisphenol A epoxy resin, 33 g of hexahydrophthalic acid diglycidyl ester, 77 g of methyltetrahydrophthalic anhydride, 15 g of polyamide resin, 0.5 g of dimethylbenzylamine, 10 g of polypropylene glycol diglycidyl ether, and 465 g of alumina particles at 50° C. for 4 h, add them to a final mixing tank, stir them at 50° C. and a vacuum degree of 300 Pa for 2 h to obtain a high thermal conductivity epoxy material, and add the high thermal conductivity epoxy material to a constant temperature glue tank of a winding equipment, wherein the temperature of the constant temperature glue tank is 60° C.

(2) The dipping and winding reel provides traction force, and the 4400Tex glass fiber bundle is dipping and winding the fiber for use through the warp frame, guide rollers, dipping tank, scraper plate and other structures. Through this process, the weight content of the dipping fiber is controlled at 60%-65%.

(3) Place 5 rolls of spare dipped fiber discs on the dipped yarn rack, and lead out 5 bundles of fibers respectively through the yarn arrangement, guide roller, and yarn winding arm for fiber winding and encapsulation.

(4) The high thermal conductivity encapsulation layer of the dry-type air-core reactor is composed of a layer of flat-wound fiber bundles and a layer of flower-wound fiber bundles, wherein the flower-wound fiber bundles are in contact with the coil. Production of the flat-wound fiber bundle: As shown in FIG1, a fiber band 1 composed of 5 fiber bundles is wound on the surface of the coil 2 of the dry-type air-core reactor from one end to the other end in a spiral manner with a spacing less than the width of the fiber band, forming a flat-wound fiber bundle layer, and the fiber band is wound in a flat overlapping manner, and the overlap width 3 of the fiber band is 12 mm; Production of the flower-wound fiber bundle: As shown in FIG2, a fiber band composed of 5 fiber bundles is wound back and forth from one end to the other end in a spiral manner with a spacing greater than the width 5 of the fiber band on the outside of the coil of the dry-type air-core reactor, forming a fiber bundle flower-wound fiber bundle layer, the flower-wound pitch is 260 mm, and the fiber bundle flower-wound fiber bundle layer is wound back and forth from one end to the other end in a spiral manner with a spacing greater than the width 5 of the fiber band, and the mesh spacing 4 of the fiber bundle flower-wound fiber bundle layer is 80 mm.

(5) After several encapsulation windings are completed, the encapsulation is placed in a curing furnace for curing to obtain a high thermal conductivity encapsulation layer of a dry-type air-core reactor.

The technical contents and technical effects not mentioned are the same as those in Example 1, so they will not be repeated here.

Example 5

The invention discloses a high thermal conductivity encapsulation layer of a dry-type air-core reactor, wherein the encapsulation layer comprises: a fiber bundle flat winding layer and a fiber bundle flower winding layer overlapped and bonded by a high thermal conductivity epoxy material; wherein the fiber bundle flower winding layer is in contact with a coil of the reactor.

Based on the same inventive concept, the present invention also provides a method for preparing a high thermal conductivity encapsulation layer of a dry-type air-core reactor, which is used for preparing the high thermal conductivity encapsulation layer of the dry-type air-core reactor. The preparation method comprises the following steps:

S1: Pulling the fiber bundle through the liquid high thermal conductivity epoxy material continuously by a pulling device to obtain the impregnated fiber bundle;

S2: Arranging the dipped fiber bundle into a fiber tape through a yarn arrangement device;

S3: Winding the fiber tape in a spiral manner with a spacing smaller than the width of the fiber tape on the surface of the coil of the reactor to form a fiber bundle flat winding layer;

S4: reciprocatingly winding the fiber tape on the surface of the fiber bundle flat winding layer from one end to the other end in a spiral manner with a spacing greater than the width of the fiber tape to form a fiber bundle flower winding layer;

S5: placing the reactor after completing steps S4 and S5 in a curing furnace for curing to obtain the high thermal conductivity encapsulation layer of the dry-type air-core reactor.

The preparation method comprises steps S3 and S4 which are repeated alternately for a plurality of times.

The step S3 or S4 includes winding a plurality of fiber tapes simultaneously.

The overlap width of the fiber tapes of the fiber bundle flat winding layer is within a range of 10-20 mm.

The fiber bundle winding layer has a winding pitch of 250-350 mm.

The fiber bundle winding layer has a winding grid spacing of 30-80 mm.

The specific implementation steps of the method for preparing a high thermal conductivity encapsulation layer of a dry-type air-core reactor are as follows:

(1) Preheat 67 g of bisphenol A epoxy resin, 33 g of hexahydrophthalic acid diglycidyl ester, 77 g of methyl hexahydrophthalic anhydride, 15 g of polyamide resin, 0.5 g of dimethylbenzylamine, 10 g of polypropylene glycol diglycidyl ether, and 465 g of alumina particles at 50° C. for 4 h, add them to a final mixing tank, stir at 50° C. and a vacuum degree of 300 Pa for 2 h to obtain a high thermal conductivity epoxy material, and add the high thermal conductivity epoxy material to a constant temperature glue tank of a winding equipment, wherein the temperature of the constant temperature glue tank is 60° C.

(2) The dipping and winding reel provides traction force, and the 4400Tex glass fiber bundle is dipping and winding the fiber for use through the warp frame, guide rollers, dipping tank, scraper plate and other structures. Through this process, the weight content of the dipping fiber is controlled at 60%-65%.

(3) Place 5 rolls of spare dipped fiber discs on the dipped yarn rack, and lead out 5 bundles of fibers respectively through the yarn arrangement, guide roller, and yarn winding arm for fiber winding and encapsulation.

(4) The high thermal conductivity encapsulation layer of the dry-type air-core reactor is composed of a layer of flat-wound fiber bundles and a layer of flower-wound fiber bundles, wherein the flower-wound fiber bundles are in contact with the coil. Production of the flat-wound fiber bundle: As shown in FIG1, a fiber band 1 composed of 5 fiber bundles is wound on the surface of the coil 2 of the dry-type air-core reactor from one end to the other end in a spiral manner with a spacing less than the width of the fiber band, forming a flat-wound fiber bundle layer, and the fiber band is wound in a flat overlapping manner, and the overlap width 3 of the fiber band is 18 mm; Production of the flower-wound fiber bundle: As shown in FIG2, a fiber band composed of 5 fiber bundles is wound back and forth from one end to the other end in a spiral manner with a spacing greater than the width 5 of the fiber band on the outside of the coil of the dry-type air-core reactor, forming a fiber bundle flower-wound fiber bundle layer, the flower-wound pitch is 350 mm, and the fiber bundle flower-wound fiber bundle layer is wound back and forth from one end to the other end in a spiral manner with a spacing greater than the width 5 of the fiber band, and the mesh spacing 4 of the fiber bundle flower-wound fiber bundle layer is 70 mm.

(5) After several encapsulation windings are completed, the encapsulation is placed in a curing furnace for curing to obtain a high thermal conductivity encapsulation layer of a dry-type air-core reactor.

The technical contents and technical effects not mentioned are the same as those in Example 1, so they will not be repeated here.

Example 6

The invention discloses a high thermal conductivity encapsulation layer of a dry-type air-core reactor, wherein the encapsulation layer comprises: a fiber bundle flat winding layer and a fiber bundle flower winding layer overlapped and bonded by a high thermal conductivity epoxy material; wherein the fiber bundle flower winding layer is in contact with a coil of the reactor.

Based on the same inventive concept, the present invention also provides a method for preparing a high thermal conductivity encapsulation layer of a dry-type air-core reactor, which is used for preparing the high thermal conductivity encapsulation layer of the dry-type air-core reactor. The preparation method comprises the following steps:

S1: Pulling the fiber bundle through the liquid high thermal conductivity epoxy material continuously by a pulling device to obtain the impregnated fiber bundle;

S2: Arranging the dipped fiber bundle into a fiber tape through a yarn arrangement device;

S3: Winding the fiber tape in a spiral manner with a spacing smaller than the width of the fiber tape on the surface of the coil of the reactor to form a fiber bundle flat winding layer;

S4: reciprocatingly winding the fiber tape on the surface of the fiber bundle flat winding layer from one end to the other end in a spiral manner with a spacing greater than the width of the fiber tape to form a fiber bundle flower winding layer;

S5: placing the reactor after completing steps S4 and S5 in a curing furnace for curing to obtain the high thermal conductivity encapsulation layer of the dry-type air-core reactor.

The preparation method comprises steps S3 and S4 which are repeated alternately for a plurality of times.

The step S3 or S4 includes winding a plurality of fiber tapes simultaneously.

The overlap width of the fiber tapes of the fiber bundle flat winding layer is within a range of 10-20 mm.

The fiber bundle winding layer has a winding pitch of 250-350 mm.

The fiber bundle winding layer has a winding grid spacing of 30-80 mm.

The specific implementation steps of the method for preparing a high thermal conductivity encapsulation layer of a dry-type air-core reactor are as follows:

(1) Preheat 67 g of bisphenol A epoxy resin, 33 g of hexahydrophthalic acid diglycidyl ester, 77 g of methyl hexahydrophthalic anhydride, 15 g of polyamide resin, 0.5 g of dimethylbenzylamine, 15 g of polypropylene glycol diglycidyl ether, and 465 g of alumina particles at 50° C. for 4 h, add them to a final mixing tank, stir at 50° C. and a vacuum degree of 300 Pa for 2 h to obtain a high thermal conductivity epoxy material, and add the high thermal conductivity epoxy material to a thermostatic glue tank of a winding equipment, wherein the temperature of the thermostatic glue tank is 60° C.

(2) The dipping and winding reel provides traction force, and the 4400Tex glass fiber bundle is dipping and winding the fiber for use through the warp frame, guide rollers, dipping tank, scraper plate and other structures. Through this process, the weight content of the dipping fiber is controlled at 60%-65%.

(3) Place 5 rolls of spare dipped fiber discs on the dipped yarn rack, and lead out 5 bundles of fibers respectively through the yarn arrangement, guide roller, and yarn winding arm for fiber winding and encapsulation.

(4) The high thermal conductivity encapsulation layer of the dry-type air-core reactor is composed of a layer of fiber bundle flat winding layer and a layer of fiber bundle flower winding layer, wherein the flower winding layer is in contact with the coil. Production of the flat winding layer: As shown in FIG1, a fiber band 1 composed of 5 fiber bundles is wound on the surface of the coil 2 of the dry-type air-core reactor from one end to the other end in a spiral manner with a spacing less than the width of the fiber band, forming a fiber bundle flat winding layer, forming a fiber band flat overlapped winding, and the fiber band overlap width 3 is 19mm; Production of the flower winding layer: As shown in FIG2, a fiber band composed of 5 fiber bundles is wound back and forth from one end to the other end in a spiral manner with a spacing greater than the width of the fiber band 5 on the outside of the coil of the dry-type air-core reactor, forming a fiber bundle flower winding layer, the flower winding pitch is 320mm, and it is wound back and forth from one end to the other end, and the grid spacing 4 of the fiber bundle flower winding layer is 65mm.

(5) After completing several encapsulation windings, the encapsulation is placed in a curing furnace for curing to obtain a high thermal conductivity encapsulation layer of a dry-type air-core reactor.

The technical contents and technical effects not mentioned are the same as those in Example 1, so they will not be repeated here.

Table 1: Experimental data summary

Table 2 Performance indicators of materials prepared in Example

Test items Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Viscosity mPa·s (60℃) 1500 800 1050 1200 1250 1100 Breakdown strength/kV/mm(1mm) 37 34 32 28 31 32 Thermal conductivity/W/m·K 1.15 1.18 1.26 1.25 1.28 1.23 Glass transition temperature/℃ 128 120 118 119 123 121 Unnotched impact strength/kJ/m2 17.4 19.6 22.1 18.5 19.2 20.7 Tensile strength/MPa 72 82 75 69 74 75

It can be seen from the above experimental results that the epoxy resin compositions provided in Examples 1-6 all have excellent thermal conductivity, electrical and mechanical properties, and have excellent process performance and impact resistance.

Table 3: The temperature rise control effect of the 500kV dry-type air-core reactor using the high thermal conductivity encapsulation layer of the present invention is as follows:

The famous "six-degree principle" in the field of electrical engineering refers to the speed of transformer insulation aging. When the transformer winding temperature is in the range of 80-130°C, the insulation aging speed will double for every 6°C increase in temperature, that is, the insulation life will be reduced by 1/2 for every 6°C increase in temperature. This is the "six-degree principle" of transformer insulation aging. Therefore, the life of the high thermal conductivity encapsulation layer proposed in the present invention can achieve a beneficial technical effect of doubling or even longer service life compared to conventional dry-type reactors, with huge economic benefits.

Example 7

The invention discloses a high thermal conductivity encapsulation layer of a dry hollow reactor, the encapsulation layer comprising: a fiber bundle flat winding layer and a fiber bundle flower winding layer overlapped and bonded by a high thermal conductivity epoxy material; wherein the fiber bundle flower winding layer is in contact with the coil of the reactor. The high thermal conductivity epoxy material comprises: 67g of bisphenol A epoxy resin with an epoxy value of 0.55, 33g of hexahydrophthalic acid glycidyl ester, 85g of methyl hexahydrophthalic anhydride, 15g of polyamide resin, 0.2g of dimethylbenzylamine, 8g of 1,4-butanediol diglycidyl ether, and 300g of AlN particles are preheated at 50°C for 4h, then added to a final mixing tank, stirred at 50°C and a vacuum degree of 300Pa for 2h to obtain a high thermal conductivity epoxy material, and the high thermal conductivity epoxy material is added to a constant temperature glue tank of a winding equipment, and the temperature of the constant temperature glue tank is 60°C.

The contents not mentioned in this embodiment are the same as those in Embodiment 1, so they will not be described again.

Example 8

The invention discloses a high thermal conductivity encapsulation layer for a dry-type hollow reactor, the encapsulation layer comprising: a fiber bundle flat winding layer and a fiber bundle flower winding layer overlapped and bonded by a high thermal conductivity epoxy material; wherein the fiber bundle flower winding layer is in contact with the coil of the reactor. The high thermal conductivity epoxy material comprises: preheating 100g of hexahydrophthalic acid glycidyl ester, 100g of methyl hexahydrophthalic anhydride, 1.5g of dimethylbenzylamine, 9g of polypropylene glycol, and 350g of SiC particles at 50°C for 4h respectively, then adding them to a final mixing tank, stirring at 50°C and a vacuum degree of 300Pa for 2h to obtain a high thermal conductivity epoxy material, and adding the high thermal conductivity epoxy material to a constant temperature glue tank of a winding equipment, the temperature of the constant temperature glue tank being 60°C.

The contents not mentioned in this embodiment are the same as those in Embodiment 1, so they will not be described again.

Example 9

The invention discloses a high thermal conductivity encapsulation layer of a dry-type hollow reactor, the encapsulation layer comprising: a fiber bundle flat winding layer and a fiber bundle flower winding layer overlapped and bonded by a high thermal conductivity epoxy material; wherein the fiber bundle flower winding layer is in contact with the coil of the reactor. The high thermal conductivity epoxy material comprises: 100g of hexahydrophthalic acid and glycidyl ester, 70g of methyl hexahydrophthalic anhydride, 15g of polyamide resin, 1.1g of dimethylbenzylamine, 8g of polypropylene glycol diglycidyl ether, 4g of 1,4-butanediol diglycidyl ether, and 400g of ZnO particles are preheated at 50°C for 4h, then added to a final mixing tank, stirred at 50°C and a vacuum degree of 300Pa for 2h to obtain a high thermal conductivity epoxy material, and the high thermal conductivity epoxy material is added to a constant temperature glue tank of a winding equipment, and the temperature of the constant temperature glue tank is 60°C.

The contents not mentioned in this embodiment are the same as those in Embodiment 1, so they will not be described again.

The thermal conductivity of aluminum nitride AlN, silicon carbide SiC and zinc oxide ZnO are much higher than that of alumina Al ₂ O ₃ , which can greatly improve the thermal conductivity of the encapsulation layer. However, due to their high cost, they are not suitable for widespread practical use in the manufacture of encapsulation layers. However, with technological advances, the production costs of these high thermal conductivity fillers may be greatly reduced, so they are used as high-performance alternatives for high thermal conductivity fillers.

Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the present invention.

Claims (20)

1. A high thermal conductivity encapsulating layer for a dry air reactor, the encapsulating layer comprising: the fiber bundle flat winding layer and the fiber bundle flower winding layer are overlapped and bonded through the high-heat-conductivity epoxy material; wherein the fiber bundle flower winding layer is in contact with the coil of the reactor.

2. A dry air reactor highly thermally conductive encapsulant layer as set forth in claim 1 wherein said highly thermally conductive epoxy material comprises: 100 parts of epoxy resin, 80-100 parts of curing agent, 0.2-1.5 parts of accelerator, 300-465 parts of inorganic heat conducting filler and 8-15 parts of toughening agent.

3. A dry air reactor high thermal conductivity encapsulating layer as recited in claim 1, wherein said epoxy resin comprises one or more combinations of bisphenol a type epoxy resin, diglycidyl hexahydrophthalate.

4. A dry air reactor highly thermally conductive encapsulant layer as claimed in claim 2 wherein said curing agent is one or a combination of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and polyamide resin.

5. The high heat conduction encapsulating layer of a dry air reactor as set forth in claim 2 wherein said high heat conduction epoxy material is prepared by the steps of: respectively preheating epoxy resin, a curing agent, an accelerator, an inorganic heat-conducting filler and a toughening agent to the same temperature; and adding the preheated raw materials into a mixing container, and uniformly stirring under a constant-temperature vacuum environment to obtain the high-heat-conductivity epoxy material.

6. A dry air reactor highly thermally conductive encapsulant layer as claimed in claim 3, wherein said bisphenol a type epoxy resin has an epoxy value of 0.55 to 0.58.

7. A dry air reactor highly thermally conductive encapsulant layer as set forth in claim 4, wherein said polyamide resin has an amine value of 180-300.

8. A dry air reactor high thermal conductivity encapsulating layer as defined in claim 2, wherein said inorganic thermal conductive filler comprises one or a combination of several of Al ₂O₃, znO, alN, siC.

9. A dry air reactor highly thermally conductive encapsulant layer as set forth in claim 8 wherein said Al ₂O₃ comprises surface activated amorphous α -Al ₂O₃.

10. A dry air reactor highly thermally conductive encapsulant layer as claimed in claim 9 wherein said amorphous α -Al ₂O₃ has a median diameter size of 5-30 μm.

11. A dry air reactor high thermal conductivity encapsulating layer according to claim 2, wherein said toughening agent comprises one or more of polypropylene glycol diglycidyl ether, 1, 4-butanediol diglycidyl ether, polypropylene glycol.

12. A dry air reactor high thermal conductivity encapsulating layer according to claim 11, wherein said polypropylene glycol diglycidyl ether has a molecular weight of 288-462.

13. A dry air reactor high thermal conductivity encapsulating layer as defined in claim 1, wherein said fiber bundles used for said fiber bundle flat winding layer and said fiber bundle flower winding layer are alkali-free and twist-free glass fiber bundles.

14. A dry air reactor highly thermally conductive encapsulant layer as set forth in claim 13 wherein said alkali-free untwisted glass fiber strands have a linear density of 1200-4800Tex.

15. A method for preparing a high heat conduction encapsulating layer of a dry air-core reactor, which is used for preparing the high heat conduction encapsulating layer of the dry air-core reactor according to any one of claims 1 to 14, and is characterized in that the preparation method comprises the following steps:

S1: pulling the fiber bundles continuously through the liquid high-heat-conductivity epoxy material by using a traction device to obtain gum dipping fiber bundles;

S2: the gum dipping fiber bundles are arranged into fiber belts through yarn arranging equipment;

S3: winding the fiber band on the surface of the coil of the reactor in a spiral line mode with the interval smaller than the width of the fiber band to form a fiber bundle flat winding layer;

s4: the fiber band is wound on the surface of the fiber bundle flat winding layer in a reciprocating mode from one end to the other end in a spiral line mode with the interval larger than the width of the fiber band to form a fiber bundle flower winding layer;

s5: and (3) placing the reactor subjected to the steps S4 and S5 in a curing furnace for curing to obtain the high-heat-conductivity encapsulation layer of the dry type air-core reactor.

16. A method of preparing a high thermal conductivity encapsulating layer for a dry air reactor according to claim 15, wherein the method comprises steps S3 and S4 of alternating cycles.

17. The method of claim 15, wherein the step S3 or S4 comprises winding a plurality of fiber tapes simultaneously.

18. A method of making a high thermal conductivity encapsulating layer for a dry air reactor according to claim 15 wherein the ribbon lap width of the ribbon lap layer comprises 10-20mm.

19. The method of producing a high thermal conductivity encapsulating layer for a dry air reactor according to claim 15, wherein the spline pitch of the fiber bundle spline winding layer comprises 250-350mm.

20. The method for preparing a high thermal conductivity encapsulating layer of a dry type air reactor according to claim 15, wherein the flower-wound mesh spacing of the fiber bundle flower-wound layer is 30-80mm.