Anti-halo structure of stator bar

Abstract

The present application relates to a kind of stator bar anti-hum structure, it is by being arranged in the low-resistance anti-hum layer of the straight section of stator bar and the high-resistance anti-hum layer being arranged in the end of the stator bar and partially lap on the low-resistance anti-hum layer, the low-resistance anti-hum layer is formed by low-resistance paint curing, the high-resistance anti-hum layer is formed by high-resistance paint curing.The stator bar anti-hum structure of the present application is formed by the low-resistance anti-hum layer of low-resistance paint curing and the high-resistance anti-hum layer of high-resistance paint curing, simple structure, convenient construction, and good anti-hum performance.

Description

Technical Field

[0001] This invention belongs to the technical field of anti-corona structure for high-voltage motors, and specifically relates to an anti-corona structure for stator bars. Background Technology

[0002] Corona prevention is a crucial technology for high-voltage motors. With the increasing rated voltage and capacity of high-voltage motors, the requirements for anti-corona materials are becoming increasingly stringent. Traditional brush-wrapping anti-corona processes require thoroughly brushing the fiberglass tape during construction, which is inconvenient and introduces numerous air pockets, hindering the improvement of corona initiation voltage and impacting the long-term service life of the unit. Furthermore, these anti-corona structures are relatively large, limiting the improvement of unit design capabilities to some extent.

[0003] Patent CN 105245050 B discloses a secondary multi-layer anti-corona structure. A low-resistance paint is applied to the outer layer of the low-resistance band, and a polyester fiber shrink tape layer is first wrapped around the high-resistance band before applying high-resistance paint. The low-resistance and high-resistance parts overlap. This structure can improve the corona performance of the motor to some extent, but it suffers from complex manufacturing processes, and the corona initiation voltage of a single stator bar is around 30kV, resulting in a relatively low rated voltage for the unit.

[0004] Patent CN 113726112B discloses a layered anti-corona structure, which involves wrapping an epoxy-coated mica tape between low-resistance and medium-resistance, and between medium-resistance and high-resistance bands, and then heating and curing it. This structure can improve the dielectric properties of the stator bars while protecting the overlapping positions of the multi-layer anti-corona layers, strengthening the adhesion of the anti-corona layers, avoiding delamination of the stator bar anti-corona layers and uncontrollable resistance values ​​at the anti-corona overlaps, thus ensuring the stability of the stator bar's anti-corona performance. However, this structure is complex and inconvenient to operate.

[0005] In summary, existing anti-sickness structures suffer from problems such as complex structure, cumbersome construction, and poor anti-sickness performance. Summary of the Invention

[0006] The purpose of this invention is to provide a stator bar anti-corona structure that is simple in structure and has good anti-corona performance.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A stator bar anti-corona structure comprises a low-resistance anti-corona layer disposed on a straight section of the stator bar and a high-resistance anti-corona layer disposed at the end of the stator bar and partially overlapping the low-resistance anti-corona layer. The low-resistance anti-corona layer is formed by curing low-resistance paint, and the high-resistance anti-corona layer is formed by curing high-resistance paint.

[0009] The stator bar anti-corona structure of the present invention eliminates the traditional reinforcing layer (such as glass fiber tape layer), thereby reducing the porosity left by the traditional process, which is beneficial to reduce partial discharge and improve anti-corona performance. In addition, the structure is simple and easier to construct.

[0010] Preferably, the high-resistance paint consists of separately packaged components A and B. Component A, with a total mass of 100%, comprises the following components: 20%–25% epoxy resin, 45%–60% powder, and 15%–35% first organic solvent. The powder is composed of silicon carbide, a nano-core-shell structure modifier, and filler. The mass ratio of silicon carbide to the nano-core-shell structure modifier is 100:(5–30), and the mass ratio of silicon carbide to the filler is 100:(0.5–5). The core of the nano-core-shell structure modifier is silicon carbide, and the shell layer is selected from one or more of silicon oxide, alumina, and titanium oxide. Component B, with a total mass of 100%, comprises the following components: 40%–55% polyamide resin and 45%–60% second organic solvent. The high-resistivity paint provided by this invention has high resistance, high corona initiation voltage and high voltage resistance, which can reduce the surface electric field strength and thus reduce the probability of corona occurrence.

[0011] Preferably, the mass ratio of silicon carbide to nano-core-shell structure modifier in the powder is 100:(5-20), for example, 100:5, 100:8, 100:10, 100:13, 100:15, 100:18, or 100:20. Too much or too little nano-core-shell structure modifier will affect the performance of the high-resistance paint; preferably, the ratio within the above range can simultaneously improve corona initiation voltage and corona resistance.

[0012] Preferably, the silicon carbide in the powder has a mesh size of 300 to 800.

[0013] In some embodiments, the silicon carbide in the powder is a mixture of first silicon carbide and second silicon carbide. The first silicon carbide has a mesh size of 300-350 mesh, and the second silicon carbide has a mesh size of 600-800 mesh. Further, the mass ratio of the first silicon carbide to the second silicon carbide is 1:(0.5-1.5), more preferably 1:(0.6-1.2). By optimizing the silicon carbide, the performance of high-resistance paint can be further improved.

[0014] Preferably, the preparation method of the nano-core-shell structure modifier includes: dispersing silicon carbide in solvent I, selectively adding a catalyst to prepare a first mixture, dissolving a precursor in solvent II, selectively adding a chelating agent to prepare a second mixture, then adding the second mixture dropwise into the first mixture for reaction, and after the reaction is completed, washing, filtering, drying and calcining are performed, wherein the precursor is selected from one or more of tetraethyl silicate, aluminum isopropoxide and tetrabutyl titanate.

[0015] In some embodiments, when preparing the silicon oxide shell, the preparation method specifically includes: dispersing silicon carbide in solvent I, adding a catalyst, wherein the catalyst is ammonia water with a mass concentration of 20% to 30%, to prepare a first mixture; dissolving tetraethyl silicate in solvent II to prepare a second mixture; then adding the second mixture dropwise into the first mixture; reacting at 20 to 30°C; and after the reaction is completed, performing the steps of filtration, washing, drying, and calcination.

[0016] Preferably, the mass ratio of silicon carbide to tetraethyl silicate in the nano-core-shell structure modifier is 1:(1.3-1.8), and more preferably 1:(1.5-1.7).

[0017] Specifically, when preparing the silicon oxide shell, the reaction time is controlled to be 5 to 6 hours.

[0018] Specifically, the mass ratio of silicon carbide to catalyst (ammonia) in the nano-core-shell structure modifier is 1:(0.1-0.5), and more preferably 1:(0.2-0.35).

[0019] Specifically, solvent I is water (such as distilled water) and / or ethanol.

[0020] Furthermore, the mass-to-volume ratio of silicon carbide to solvent I in the nano-core-shell structure modifier is 1 g: (2-20) mL.

[0021] Specifically, solvent II is ethanol and / or isopropanol.

[0022] Furthermore, the mass-to-volume ratio of the precursor to solvent II in the nano-core-shell structure modifier is 1 g:(0.5-100) mL, more preferably 1:(1-20), for example 1:1, 1:1.5, 1:2, 1:5, 1:10, 1:20.

[0023] Specifically, the calcination temperature is 500–700°C.

[0024] Furthermore, the calcination time is 1 to 6 hours.

[0025] Preferably, the low-resistance paint consists of separately packaged mixture I and mixture II. Mixture I, based on 100% of its total mass, comprises the following components: 35%–50% epoxy resin, 2%–10% conductive carbon black, 5%–15% graphite, 0–1% additives, and 35%–50% first organic solvent. Mixture II, based on 100% of its total mass, comprises the following components: 40%–55% polyamide resin and 45%–60% second organic solvent.

[0026] More preferably, based on the total mass of the mixture I as 100%, the mixture I comprises the following components: 40% to 45% epoxy resin, 5% to 8% conductive carbon black, 6% to 10% graphite, 0.1% to 0.5% additives, and 40% to 45% first organic solvent.

[0027] Preferably, the filler in the high-resistance paint is selected from one or more of acetylene black, graphite, quartz powder, zinc oxide, fumed silica, and iron oxide red.

[0028] Preferably, the first organic solvent and the second organic solvent in the high-resistance paint and the low-resistance paint are each independently selected from one or more of toluene, butanol, and acetone, and the first organic solvent and the second organic solvent in the high-resistance paint and the low-resistance paint may be the same or different.

[0029] Preferably, the additive in the low-resistivity paint is fumed silica.

[0030] Preferably, the thickness of the high-resistance anti-corona layer is 150μm to 400μm, more preferably 200μm to 300μm, such as 200μm, 220μm, 240μm, 260μm, 280μm, and 300μm.

[0031] Preferably, the thickness of the low-resistance anti-corona layer is 50μm to 200μm, for example, 80μm, 100μm, 120μm, 140μm, or 180μm.

[0032] Preferably, the length of the portion of the high-resistance anti-corona layer overlapping the low-resistance anti-corona layer is 20mm to 30mm, and more preferably 23mm to 28mm.

[0033] Preferably, the low-resistivity paint and the high-resistivity paint are applied to the stator bars by a roller coating process.

[0034] In some embodiments, when using the low-resistivity paint, the mixture I and the mixture II are mixed evenly at a mass ratio of (10-15):1, and then coated onto the stator bar.

[0035] In some embodiments, when using the high-resistance paint, component A and component B are mixed evenly at a mass ratio of (10-15):1, and then coated onto the stator bar.

[0036] Preferably, the stator bar includes a stator conductor and a stator main insulation formed on the surface of the stator conductor.

[0037] In some embodiments, the stator primary insulation includes a low-resin mica tape layer formed on the surface of the stator conductor and a resin formed in the low-resin mica tape layer.

[0038] Furthermore, the method for forming the resin includes: impregnating the resin using a vacuum pressure impregnation process, then wrapping a polytetrafluoroethylene film flat on the outside of the resin-impregnated low-adhesion mica tape layer, fixing it with a mold, baking and curing it, and removing the mold and the polytetrafluoroethylene film after the curing is completed and the material is naturally cooled to less than or equal to 50°C.

[0039] Preferably, the low-adhesion mica tape layer is formed by semi-overlapping 10 to 30 layers on the surface of the stator conductor.

[0040] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0041] The stator bar anti-corona structure of the present invention consists of a low-resistivity anti-corona layer formed by curing low-resistivity paint and a high-resistivity anti-corona layer formed by curing high-resistivity paint. It has a simple structure, is easy to construct, and has good anti-corona performance. Attached Figure Description

[0042] Figure 1 A schematic diagram of an anti-sickness structure provided by the present invention;

[0043] Among them, 1. Stator conductor; 2. Stator main insulation; 3. Low resistance anti-corona layer; 4. Overlap section; 5. High resistance anti-corona layer. Detailed Implementation

[0044] The present invention will be further described below with reference to embodiments. However, the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific applications, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0045] Unless otherwise specified, all raw materials mentioned below are commercially available products or can be prepared by referring to existing preparation methods.

[0046] Unless otherwise specified, the two-component anti-halo low-resistivity paint used below shall be prepared according to the following steps:

[0047] Step 1: Take 50g of toluene solvent and 50g of butanol solvent respectively, mix them evenly to form a mixed solvent, take 100g of bisphenol A type epoxy resin E-20 (Jiangsu Sanmu Group Co., Ltd.) and 0.5g of fumed silica, disperse them in the mixed solvent to prepare resin varnish, then add 15g of conductive carbon black and 20g of graphite powder, stir evenly, and sand mill for 1 hour to prepare resin component.

[0048] Step 2: Weigh 25 grams of toluene and 25 grams of butanol to prepare a mixed solvent. Add 40 grams of low molecular weight polyamide resin 600 (Jiangsu Sanmu Group Co., Ltd.) to the mixed solvent and mix evenly to prepare the curing agent component.

[0049] Step 3: During construction, mix the resin component and the curing agent component evenly at a mass ratio of 14:1, apply with rollers, and dry at room temperature (25±5℃) before baking to obtain the low resistance anti-corona layer 3.

[0050] Unless otherwise specified, the two-component anti-halo high-resistance paint used below shall be prepared according to the following steps:

[0051] (1) Take 50g of toluene solvent and 50g of butanol solvent respectively, mix them evenly and use them as mixed solvents. Take 100g of bisphenol A type epoxy resin E-20 (Jiangsu Sanmu Group Co., Ltd.) and 0.5g of fumed silica, disperse them in the mixed solvents to prepare resin varnish. Then add 100g of 320-mesh silicon carbide powder and 120g of 600-mesh silicon carbide powder to it, stir evenly, add 15g of core-shell structure modifier SiC@SiO2 with SiO2 as shell and SiC as core and 2g of iron oxide red, stir evenly and prepare component A.

[0052] (2) Weigh 25g of toluene and 25g of butanol to prepare a mixed solvent. Add 40g of low molecular weight polyamide resin 600 (Jiangsu Sanmu Group Co., Ltd.) to the mixed solvent to prepare component B.

[0053] (3) During construction, mix component A and component B evenly at a mass ratio of 10:1, apply with rollers, and dry at room temperature before baking to obtain the anti-dizziness layer.

[0054] Unless otherwise specified, the preparation method of the core-shell structure modifier SiC@SiO2 described in this article is as follows:

[0055] Place 100 mL of distilled water in a three-necked flask, add 15 g of the nuclear raw material powder (silicon carbide) to be treated, stir and ultrasonically disperse for 0.5 h, then add 3 mL of 25% ammonia water and stir for 10 min to obtain solution A. Separately, take 25 mL of tetraethyl silicate and 40 mL of anhydrous ethanol, mix and stir for 10 min, place in a dropping funnel, and add dropwise to solution A at a rate of 1 drop / min while continuously stirring. After the addition is complete, react at room temperature for 6 h. Filter to obtain powder, wash in 100 mL of distilled water, filter again, wash and filter again as before, dry at 100℃, calcine at 600℃ for 4 h, and sieve. Before use, dry (120-130℃, 1-2 h) to remove moisture.

[0056] Example 1

[0057] The main insulation is designed according to the rated voltage of 27kV, including: 20 layers of 0.15mm×30mm low-adhesion mica tape JF-5442-1T (Suzhou Jufeng Electrical Insulation System Co., Ltd.) are half-overlapped on the surface of the conductor bar (i.e., stator conductor 1) for main insulation wrapping. After completion, it is treated with JF-9955 epoxy anhydride resin (Suzhou Jufeng Electrical Insulation System Co., Ltd.) VPI. After impregnation, a layer of 0.05mm×60mm polytetrafluoroethylene film tape (Yangzhong Aifusi Pipe Valve Co., Ltd.) is flatly wrapped on the outer surface. It is then baked and cured in a mold. After curing, it is naturally cooled to 50℃ and the mold and polytetrafluoroethylene film tape are removed to form the stator main insulation 2.

[0058] After the main stator insulation 2 is cured, an anti-corona layer is made. The total length of the conductor bar is 1850mm. The middle 500mm is coated with low-resistivity paint, and the two ends are coated with high-resistivity paint symmetrically outwards. The overlap length is 25mm, and the total length of the high-resistivity paint is 620mm.

[0059] Apply two coats of two-component anti-halo low-resistivity paint to the straight section, with a 40-minute interval between each coat. Apply two-component anti-halo high-resistivity paint to the ends, with a 25-mm overlap between the high and low resistance layers (i.e., the overlap length of section 4 is 25mm). Apply three coats by roller, with an interval of more than 2 hours between each coat (to ensure surface drying without affecting the next roller coating). After the three roller coats are surface dry (let them sit at room temperature for more than 3 hours), place them in an oven and dry them under the following conditions: 90℃ / 20min—120℃ / 180min. This will sequentially form a low-resistivity anti-halo layer 3 and a high-resistivity anti-halo layer 5, where the thickness of the low-resistivity anti-halo layer 3 is 120μm and the thickness of the high-resistivity anti-halo layer 5 is 230μm.

[0060] Example 2

[0061] It is basically the same as Example 1, except that the thickness of the high-resistance anti-corona layer 5 formed is different.

[0062] In this embodiment, the thickness of the high-resistance anti-corona layer 5 is 350 μm.

[0063] Example 3

[0064] It is basically the same as Example 1, except that the thickness of the high-resistance anti-corona layer 5 formed is different.

[0065] In this embodiment, the thickness of the high-resistance anti-corona layer 5 is 150 μm.

[0066] Comparative Example 1

[0067] It is basically the same as Example 1, except that the low-resistance paint and high-resistance paint used are different.

[0068] In this comparative example, a low-resistance paint of brand name R-407-D (purchased from Zhejiang Rongtai Technology Co., Ltd.) was used to replace the two-component anti-halo low-resistance paint, and a high-resistance paint of brand name R-407-G (Zhejiang Rongtai Technology Co., Ltd.) was used to replace the two-component anti-halo high-resistance paint.

[0069] Comparative Example 2

[0070] It is basically the same as Example 1, except that a different high-resistance paint is used.

[0071] In this comparative example, the high-resistance paint was prepared according to the following steps:

[0072] (1) Take 50g of toluene solvent and 50g of butanol solvent respectively, mix them evenly and use them as mixed solvent. Take 100g of bisphenol A type epoxy resin E-20 (Jiangsu Sanmu Group Co., Ltd.) and 0.5g of fumed silica, disperse them in the mixed solvent to prepare resin varnish. Then add 100g of 320-mesh silicon carbide powder and 120g of 600-mesh silicon carbide powder to it, stir evenly, add 12g of 600-mesh silicon carbide, 3g of silicon dioxide nanoparticles (manufacturer: Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., brand name: XFI03, particle size: 20nm, purity: 99.9%), and 2g of iron oxide red, stir evenly to prepare component A.

[0073] (2) Weigh 25g of toluene and 25g of butanol to prepare a mixed solvent. Add 40g of low molecular weight polyamide resin 600 (Jiangsu Sanmu Group Co., Ltd.) to the mixed solvent to prepare component B.

[0074] (3) During construction, mix component A and component B evenly at a mass ratio of 10:1, and construct in the same manner as in Example 1 to obtain the anti-dizziness layer.

[0075] Performance testing: The above-mentioned wire rods were subjected to corona initiation voltage and corona resistance tests. A certain voltage was applied for 1 minute. The test was considered passed if there was no creepage, no longitudinal discharge, no smoke, and no ablation on the surface of the corona layer; otherwise, it was considered a failure. The test results are shown in Table 1.

[0076] Table 1

[0077]

[0078] The anti-corona structure formed by the high-resistivity and low-resistivity paints of this invention can effectively improve the corona initiation voltage and enhance corona resistance. Furthermore, during construction, only the high-resistivity and low-resistivity paints need to be applied to the surface of the stator bars, making construction more convenient.

[0079] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A de-homogenizing structure for stator bars, characterized by: The anti-hunting structure is composed of a low-resistance anti-hunting layer (3) arranged on a straight section of a stator bar and a high-resistance anti-hunting layer (5) arranged on an end portion of the stator bar and partially overlapping the low-resistance anti-hunting layer (3), the low-resistance anti-hunting layer (3) is formed by curing a low-resistance paint, and the high-resistance anti-hunting layer (5) is formed by curing a high-resistance paint; The high-resistance paint is composed of a component A and a component B packaged independently, the component A includes the following components, based on the total mass of the component A being 100%: Epoxy resin 20%-25%, Powder 45%-60%, First organic solvent 15%-35%, The powder is composed of silicon carbide, nano core-shell structure modifier and filler, the mass ratio of the silicon carbide to the nano core-shell structure modifier is 100: (5-30), the mass ratio of the silicon carbide to the filler is 100: (0.5-5), the core of the nano core-shell structure modifier is silicon carbide, and the shell layer of the nano core-shell structure modifier is selected from one or more of silicon oxide, aluminum oxide and titanium oxide; The component B includes the following components, based on the total mass of the component B being 100%: Polyamide resin 40%-55%, Second organic solvent 45%-60%; The low-resistance paint is composed of a mixture I and a mixture II packaged independently, the mixture I includes the following components, based on the total mass of the mixture I being 100%: Epoxy resin 35%-50%, Conductive carbon black 2%-10%, Graphite 5%-15%, Auxiliary agent 0-1%, First organic solvent 35%-50%; The mixture II includes the following components, based on the total mass of the mixture II being 100%: Polyamide resin 40%-55%, Second organic solvent 45%-60%.

2. The stator bar de-bunching structure of claim 1, wherein: The preparation method of the nano core-shell structure modifier includes: dispersing silicon carbide in a solvent I, selectively adding a catalyst to configure a first mixed solution, dissolving a precursor in a solvent II, selectively adding a chelating agent to configure a second mixed solution, then dropping the second mixed solution into the first mixed solution for reaction, and after the reaction is completed, performing cleaning, suction filtration, drying and calcination, and the precursor is selected from one or more of tetraethyl orthosilicate, aluminum isopropoxide and tetrabutyl titanate.

3. The stator bar de-bunching structure of claim 1, wherein: The filler in the high-resistance paint is selected from one or more of acetylene black, graphite, quartz powder, zinc oxide, fumed silica and iron oxide red; and / or, The first organic solvent and the second organic solvent in the high-resistance paint and the low-resistance paint are independently selected from one or more of toluene, butanol and acetone, and the first organic solvent and the second organic solvent in the high-resistance paint and the low-resistance paint are the same or different; and / or, The auxiliary agent in the low-resistance paint is fumed silica.

4. The stator bar de-bunching structure of claim 1, wherein: The thickness of the high-resistance anti-hunting layer (5) is 150 μm-400 μm.

5. The stator bar de-bunching structure of claim 1, wherein: The thickness of the low-resistance anti-hunting layer (3) is 50 μm-200 μm.

6. The stator bar de-bunching structure of claim 1, wherein: The length of the part of the high-resistance anti-hunting layer (5) overlapping the low-resistance anti-hunting layer (3) is 20 mm-30 mm.

7. The stator bar de-bunching structure of claim 1, wherein: The low-resistance paint and the high-resistance paint are coated on the stator bar by a process of roll coating.

8. The stator bar de-bunching structure of claim 1, wherein: The stator bar comprises a stator conductor (1) and a stator main insulation (2) formed on the surface of the stator conductor (1).

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