Stator bar anti-corona structure

Abstract

The invention relates to a stator bar anti-corona structure which is composed of a low-resistance anti-corona layer arranged on a straight line section of a stator bar and a high-resistance anti-corona layer arranged at the end of the stator bar and partially lapped on the low-resistance anti-corona layer, and 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. The stator bar anti-corona structure is composed of the low-resistance anti-corona layer formed by curing the low-resistance paint and the high-resistance anti-corona layer formed by curing the high-resistance paint, and is simple in structure, convenient to construct and good in anti-corona performance.

Description

Technical Field

[0001] The invention belongs to the technical field of high-voltage motor anti-corona structures, and in particular relates to a stator wire bar anti-corona structure. Background Art

[0002] Anti-corona is an important technology for high-voltage motors. With the increase of rated voltage and rated capacity of high-voltage motors, the requirements for anti-corona materials are getting higher and higher. The traditional brush-wrapped anti-corona process requires the glass fiber tape to be brushed through during construction, and the construction is inconvenient. In addition, there are many pores during the construction process, which is not conducive to the improvement of the corona inception voltage and affects the long-term service of the unit. In addition, this type of anti-corona structure is large in size, which limits the improvement of the unit design level to a certain extent.

[0003] Patent CN 105245050 B discloses a secondary multi-layer anti-corona structure, in which low-resistance paint is applied to the outer layer of the low-resistance belt, a polyester fiber shrink belt layer is first wrapped around the high-resistance belt, and then high-resistance paint is applied, and the low-resistance part and the high-resistance part are overlapped. This structure can improve the corona performance of the motor to a certain extent, but there is a problem of complex process, and the corona initiation voltage of a single stator bar is about 30kV, and the rated voltage of the unit is relatively low.

[0004] Patent CN 113726112B discloses a stacking fault anti-corona structure, which wraps a layer of epoxy multi-resin mica tape between the low resistance and medium resistance, and between the medium resistance and high resistance tapes, and then heats and solidifies them. This structure can protect the multi-layer anti-corona overlap position while improving the dielectric properties of the wire rod, strengthen the bonding performance of the anti-corona layer, avoid the anti-corona layer of the stator wire rod from stratifying, and the uncontrollable resistance value at the anti-corona overlap, and ensure the stability of the anti-corona performance of the stator wire rod. However, this structure is complicated and very inconvenient to operate.

[0005] In summary, the anti-corona structure in the prior art has the problems of complex structure, cumbersome construction and poor anti-corona performance. Summary of the invention

[0006] The object of the present invention is to provide a stator wire bar anti-corona structure with simple structure and good anti-corona performance.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

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

[0009] The stator wire rod anti-corona structure of the present invention eliminates the traditional reinforcement layer (such as glass fiber belt layer, etc.), thereby reducing the pores remaining in the traditional process, which is beneficial to reducing local discharge and improving the anti-corona performance, and has a simple structure and is more convenient to construct.

[0010] Preferably, the high-resistance paint is composed of independently packaged component A and component B. Taking the total mass of component A as 100%, component A includes the following ingredients: 20% to 25% epoxy resin, 45% to 60% powder, and 15% to 35% first organic solvent, wherein the powder is composed of silicon carbide, a nano core-shell structure modifier and a filler, the mass ratio of silicon carbide to the nano core-shell structure modifier is 100:(5 to 30), the mass ratio of silicon carbide to the filler is 100:(0.5 to 5), the core of the nano core-shell structure modifier is silicon carbide, and the shell of the nano core-shell structure modifier is selected from one or more of silicon oxide, aluminum oxide, and titanium oxide; taking the total mass of component B as 100%, component B includes the following ingredients: 40% to 55% polyamide resin and 45% to 60% second organic solvent. The high-resistance paint provided by the present invention has high resistance, high corona inception voltage and high voltage resistance, and can reduce the surface electric field intensity, thereby reducing the probability of corona occurrence.

[0011] Preferably, the mass ratio of silicon carbide to the 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, 100:20. Too much or too little nano core-shell structure modifier additive will affect the performance of the high resistance paint. Preferably, the corona inception voltage and corona resistance performance can be improved simultaneously within the above range.

[0012] Preferably, the mesh size of the silicon carbide in the powder is 300-800 meshes.

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

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

[0015] In some embodiments, when preparing a silicon oxide shell layer, 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 form a first mixed liquid, dissolving tetraethyl silicate in solvent II to form a second mixed liquid, and then dripping the second mixed liquid into the first mixed liquid, reacting at 20 to 30°C, and performing the steps of filtration, washing, drying and calcining after the reaction is completed.

[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 layer, the reaction time is controlled to be 5 to 6 hours.

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

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

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

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

[0022] Furthermore, the mass volume ratio of the precursor to the solvent II in the nano core-shell structure modifier is 1 g: (0.5-100) mL, and 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 is composed of independently packaged mixture I and mixture II. Taking the total mass of the mixture I as 100%, the mixture I includes the following components: 35% to 50% epoxy resin, 2% to 10% conductive carbon black, 5% to 15% graphite, 0 to 1% additive, and 35% to 50% first organic solvent; taking the total mass of the mixture II as 100%, the mixture II includes the following components: 40% to 55% polyamide resin and 45% to 60% second organic solvent.

[0026] Further preferably, based on the total mass of the mixture I being 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% additive, 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 red iron oxide.

[0028] Preferably, 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.

[0029] Preferably, the auxiliary agent in the low-resistance paint is fumed silica.

[0030] Preferably, the thickness of the high resistance anticorona layer is 150 μm to 400 μm, more preferably 200 μm to 300 μm, for example, 200 μm, 220 μm, 240 μm, 260 μm, 280 μm, or 300 μm.

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

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

[0033] Preferably, the low-resistance paint and the high-resistance paint are coated on the stator wire rods by roller coating process.

[0034] In some implementations, when the low-resistance paint is used, the mixture I and the mixture II are evenly mixed in a mass ratio of (10-15):1, and then coated on the stator wire rod.

[0035] In some implementations, when the high resistance paint is used, the component A and the component B are evenly mixed in a mass ratio of (10-15):1, and then coated on the stator wire rod.

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

[0037] In some embodiments, the stator main insulation includes a low-resin mica tape layer formed on a 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: using a vacuum pressure impregnation process to complete resin impregnation, then flatly wrapping a polytetrafluoroethylene film on the outside of the resin-impregnated low-resistance mica tape layer, fixing it with a mold and then baking it for curing, and removing the mold and the polytetrafluoroethylene film after naturally cooling to less than or equal to 50°C after curing.

[0039] Preferably, the low-resistance mica tape layer is formed by half-lapping 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 wire bar anti-corona structure of the present invention is composed of a low-resistance anti-corona layer formed by curing a low-resistance paint and a high-resistance anti-corona layer formed by curing a high-resistance paint, and has a simple structure, convenient construction, and good anti-corona performance. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0043] Among them, 1. stator conductor; 2. stator main insulation; 3. low resistance anti-corona layer; 4. overlapping section; 5. high resistance anti-corona layer. DETAILED DESCRIPTION

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

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

[0046] Unless otherwise specified, the two-component anti-corona low-resistance paint used below is prepared according to the following steps:

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

[0049] Step 3: During construction, the resin component and the curing agent component are mixed evenly in a mass ratio of 14:1, and the mixture is applied with a roller. The mixture is air-dried at room temperature (25±5° C.) and then baked to obtain a low-resistance anti-corona layer 3.

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

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

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

[0053] (3) During construction, component A and component B are mixed evenly in a mass ratio of 10:1, applied with a roller, and dried at room temperature to obtain an anti-corona layer.

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

[0055] Take 100mL of distilled water and place it in a three-necked flask, add 15g of the nuclear raw material powder to be processed (silicon carbide), stir and ultrasonically disperse for 0.5h, then add 3mL of 25% ammonia water, stir for 10min to obtain solution A. Take another 25mL of tetraethyl silicate and 40mL of anhydrous ethanol, mix and stir for 10min, put them into a dropping funnel, drip into solution A at a rate of 1 drop / min, continue stirring, and react at room temperature for 6h after the addition is completed. Filter the powder, wash it in 100mL of distilled water, filter it, wash and pump it again as before, dry it at 100℃, calcine it at 600℃ for 4h, and sieve it. Dry it before use (120-130℃, 1-2h) to remove moisture.

[0056] Example 1

[0057] The main insulation is designed according to the rated voltage of 27kV, including: the surface of the wire rod (i.e., the stator conductor 1) is half-wrapped with 20 layers of 0.15mm×30mm low-glue mica tape JF-5442-1T (Suzhou Jufeng Electrical Insulation System Co., Ltd.) for main insulation wrapping, and after completion, it is treated with JF-9955 epoxy anhydride resin (Suzhou Jufeng Electrical Insulation System Co., Ltd.) VPI treatment, and after impregnation, a layer of 0.05mm×60mm polytetrafluoroethylene film tape (Yangzhong Aifusi Pipe and Valve Co., Ltd.) is flatly wrapped on the outer surface, and the mold is placed on it for baking and curing. After the curing is completed, it is naturally cooled to 50°C to remove the mold and the polytetrafluoroethylene film tape to form the stator main insulation 2.

[0058] After the stator main insulation 2 is cured, the anti-corona layer is made. The total length of the wire rod is 1850mm. The middle 500mm is painted with low-resistance paint, and the two ends are painted with high-resistance paint symmetrically outward. The length of the overlapped part is 25mm, and the total length of the high-resistance paint is 620mm.

[0059] Apply two coats of two-component anti-corona low-resistance paint on the straight part, with an interval of 40 minutes between each coat, and apply two-component anti-corona high-resistance paint on the end, with an overlap of 25mm between high and low resistance (i.e., the length of the overlap section 4 is 25mm), and roll brush three times, with an interval of more than 2h between each coat (surface drying, which does not affect the next roller coating). After three times of roller brushing, the surface is dry (put at room temperature for more than 3h), put it into an oven and dry it under the following conditions, i.e., 90℃ / 20min-120℃ / 180min, to form a low-resistance anti-corona layer 3 and a high-resistance anti-corona layer 5 in turn, wherein the low-resistance anti-corona layer 3 has a thickness of 120μm, and the high-resistance anti-corona layer 5 has a thickness of 230μm.

[0060] Example 2

[0061] The method is basically the same as that of Example 1, except that the thickness of the formed high-resistance anticorona layer 5 is different.

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

[0063] Example 3

[0064] The method is basically the same as that of Example 1, except that the thickness of the formed high-resistance anticorona layer 5 is different.

[0065] In this embodiment, the thickness of the high-resistance anticorona 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 with a brand name of R-407-D (purchased from Zhejiang Rongtai Technology Enterprise Co., Ltd.) was used to replace the two-component anti-corona low-resistance paint, and a high-resistance paint with a brand name of R-407-G (purchased from Zhejiang Rongtai Technology Enterprise Co., Ltd.) was used to replace the two-component anti-corona high-resistance paint.

[0069] Comparative Example 2

[0070] The method 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 is prepared according to the following steps:

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

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

[0074] (3) During construction, component A and component B are uniformly mixed in a mass ratio of 10:1, and the anti-corona layer is obtained by construction in the same manner as in Example 1.

[0075] Performance test: The above-mentioned wire rods are subjected to corona inception voltage test and corona resistance test, with a certain voltage applied for 1 minute. The test is considered passed if there is no creepage, longitudinal discharge, smoke or ablation on the surface of the anti-corona layer, otherwise it is considered failed. The test results are shown in Table 1.

[0076] Table 1

[0077]

[0078] The anti-corona structure formed by the high-resistance paint and the low-resistance paint of the present invention can effectively increase the corona inception voltage and improve the anti-corona performance. In addition, during construction, it is only necessary to apply the high-resistance paint and the low-resistance paint on the surface of the stator wire rod, which makes the construction more convenient.

[0079] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A stator bar anti-corona structure, characterized in that: The anti-corona structure is composed of a low-resistance anti-corona layer (3) arranged on a straight section of a stator wire bar, and a high-resistance anti-corona layer (5) arranged at an end of the stator wire bar and partially overlapping the low-resistance anti-corona layer (3); the low-resistance anti-corona layer (3) is formed by curing a low-resistance paint, and the high-resistance anti-corona layer (5) is formed by curing a high-resistance paint.

2. The stator bar anti-corona structure according to claim 1, characterized in that: The high-resistance paint is composed of independently packaged component A and component B. Taking the total mass of component A as 100%, component A includes the following ingredients: Epoxy resin 20%~25%, Powder 45%~60%, The first organic solvent is 15% to 35%, The powder is composed of silicon carbide, a nano core-shell structure modifier and a filler, the mass ratio of silicon carbide to the nano core-shell structure modifier is 100:(5-30), 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 of the nano core-shell structure modifier is selected from one or more of silicon oxide, aluminum oxide and titanium oxide; Taking the total mass of component B as 100%, component B includes the following ingredients: Polyamide resin 40%~55%, The second organic solvent is 45% to 60%.

3. The stator bar anti-corona structure according to claim 2, characterized in that: The preparation method of the nano core-shell structure modifier comprises: dispersing silicon carbide in solvent I, selectively adding a catalyst to prepare a first mixed liquid, dissolving a precursor in solvent II, selectively adding a chelating agent to prepare a second mixed liquid, then dropping the second mixed liquid into the first mixed liquid for reaction, and washing, filtering, drying and calcining after the reaction is completed. The precursor is selected from one or more of tetraethyl silicate, aluminum isopropoxide and tetrabutyl titanate.

4. The stator bar anti-corona structure according to claim 1, characterized in that: The low-resistance paint is composed of independently packaged mixture I and mixture II. Taking the total mass of the mixture I as 100%, the mixture I includes the following components: Epoxy resin 35%~50%, Conductive carbon black 2% to 10%, Graphite 5% to 15%, Additives 0~1%, The first organic solvent is 35% to 50%; Taking the total mass of the mixture II as 100%, the mixture II comprises the following components: Polyamide resin 40%~55%, The second organic solvent is 45% to 60%.

5. The stator bar anti-corona structure according to claim 2 or 4, characterized in that: The filler in the high resistance paint is selected from one or more of acetylene black, graphite, quartz powder, zinc oxide, fumed silica, and red iron oxide; 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.

6. The stator bar anti-corona structure according to claim 1, characterized in that: The thickness of the high-resistance anti-corona layer (5) is 150 μm to 400 μm.

7. The stator bar anti-corona structure according to claim 1, characterized in that: The thickness of the low-resistance anti-corona layer (3) is 50 μm to 200 μm.

8. The stator bar anti-corona structure according to claim 1, characterized in that: The length of the portion of the high-resistance anti-corona layer (5) overlapping the low-resistance anti-corona layer (3) is 20 mm to 30 mm.

9. The stator bar anti-corona structure according to claim 1, characterized in that: The low-resistance paint and the high-resistance paint are coated on the stator wire rods by roller coating.

10. The stator bar anti-corona structure according to claim 1, characterized in that: 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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