An evaluation method applicable to the insulation crosslinking and curing degree of generator stator windings

Abstract

The invention discloses a method for evaluating the cross-linking and curing degree of the insulation of the stator winding of a generator, and belongs to the technical field of the stator winding material of the generator. The method comprises: testing the insulation sample of the stator winding at a heating rate k 1 The thermal weight loss curve of the stator winding insulation sample is obtained when the test temperature rises to T 1 The residual mass W T1 , and obtain the test temperature rise to T 2 The residual mass W T2 ; Test the initial weight of the stator winding insulation sample W S0 , at a temperature T s Then, the stator winding insulation sample is immersed in the solvent S to ensure that it is fully immersed; then, it is taken out of the solvent, dried thoroughly, and weighed, and the weight of the stator winding insulation sample at this time is recorded as W S1 , the solubility parameter of solvent S is SP S , the cross-linking and curing degree parameters of the stator winding insulation are calculated to ensure high test accuracy, and can well reflect the cross-linking and curing degree of the stator winding insulation. The invention has high accuracy, and the test process is fast, simple and easy to implement.

Description

Technical Field

[0001] The present invention relates to a method for evaluating the degree of crosslinking and curing, and particularly to a method for evaluating the degree of crosslinking and curing of the insulation of a generator stator winding, belonging to the technical field of generator stator winding materials. Background Art

[0002] At present, the insulation material of the stator winding of a large generator is an epoxy mica glass fiber composite material. Among them, the thermosetting epoxy resin plays roles such as an adhesive and a reinforcing agent in the insulation of the generator stator winding, which makes the insulation composite material of the generator stator winding become an integrally combined composite material. This is of great significance for evaluating the degree of crosslinking and curing of the insulation of the generator stator winding.

[0003] In the prior art CN105547896A, an analysis method for rubber foaming materials is proposed, which uses the equilibrium swelling method in combination with the results of scanning electron microscopy and calculates the degree of crosslinking and curing using a designed formula; CN105388081A proposes a method for testing the crosslinking density of foaming materials based on the equilibrium swelling method and modifies the Flory-Rehner formula; CN105424735A proposes a method for the crosslinking density in a sulfur-containing polymer composite material, irradiates the sulfur-containing polymer composite material with high-intensity X-rays, and measures the X-ray absorption spectrum of the composite material while changing the X-ray energy. Through the reverse Monte Carlo method, a visualization step for determining the three-dimensional structure of sulfur atoms in the sulfur-containing polymer composite material based on the X-ray absorption spectrum is carried out, and the crosslinking density of each bond number of sulfur atoms is calculated; CN104697927A proposes a measurement method for measuring the curing degree of an imprint or coating with a radiation-curable pigment or radiation-curable paint on a container, mainly performs such measurement on the container by an optical method, and proposes a device for implementing such a method and a computer-readable medium having computer-readable instructions for controlling such a method; CN103529070A proposes an on-line monitoring system for the curing degree of epoxy resin and a method for monitoring the curing degree of epoxy resin using this system. The on-line monitoring of the curing process of epoxy resin is realized by collecting electrical signals; CN103528947A proposes a rapid detection method for the curing degree of a polyurethane enamel film, mainly uses a tensile tester or a tensile testing machine to stretch the extracted and straightened specimens to the conductor fracture point respectively, measures the distance from the point where the film color significantly turns white to the fracture point, and judges the curing degree of the film by calculation; CN103383330A proposes a material curing degree testing system, a testing method and a method for manufacturing a solder mask layer, mainly applies force to the surface of a sample to be tested by a indenter, applies a plurality of different pressures to form indentations. The curing degree is determined by measuring the depth of the indentations; CN102753332A proposes a method for measuring crosslinking density, a method for setting conditions, a laminating treatment method for a laminated processed product, a crosslinking density measuring device and an adjusting device; CN112834548A proposes a method and device for measuring crosslinking density, and measures the crosslinking density of a material by obtaining a nuclear magnetic resonance double quantum sequence and a plurality of preset regularization parameters.

[0004] In addition, the prior art CN111505459A discloses "a method for evaluating the insulation aging of generator stator windings", which includes the following steps: a. Sample preparation; b. Determination of functional group attribution and phase change behavior: Determine the change trend of the phase behavior according to the change trend of the intensity of the characteristic absorption peak spectrum band; c. Perform two-dimensional correlation infrared high-order operation to determine the law of the movement change of each functional group during the aging process; d. Quantitative analysis of the relationship between the aging degree and the phase change intensity of the characteristic functional group. By establishing a suitable window model, extract the key spectral band parameters to quantitatively describe the relationship between the aging degree and the movement intensity of the characteristic functional group; CN101132140 discloses "a design method and an evaluation method for the insulation life of a turbo-generator stator winding". A computer software for designing the F-class insulation life of a turbo-generator stator winding is written in C language and installed on a computer in the design or research department of the turbo-generator manufacturing industry to evaluate the insulation life of the turbo-generator stator winding. The method is as follows: Determine the operating life index value of the generator, calculate the thermal aging life of the stator winding insulation, calculate the electrical aging life of the stator winding insulation, calculate the cumulative life loss of the stator winding insulation due to thermal aging, determine the limit value Dco of the cumulative life loss of the generator stator winding insulation, and perform insulation life evaluation and improved design; CN113390912A discloses "a method for evaluating the crosslinking and curing degree of the surface coating of a Si-containing fingerprint-resistant coated galvanized sheet", which includes the following steps: 1) After the Si-containing fingerprint-resistant coated galvanized sheet to be tested is subjected to the first wiping treatment with absorbent cotton, select the test area for the first Si content measurement, denoted as the initial Si content m1; 2) After the Si-containing fingerprint-resistant coated galvanized sheet to be tested is subjected to the second wiping treatment with absorbent cotton containing 2-butanone solution, perform the second Si content measurement in the same test area, denoted as the current Si content m2; 3) Calculate the coating attenuation rate a according to the initial Si content m1 and the current Si content m2, and compare the coating attenuation rate a with the set standard value b to evaluate the crosslinking and curing degree of the surface coating of the Si-containing fingerprint-resistant coated galvanized sheet; CN113916929A discloses "a method for evaluating the curing degree of the main insulation of a generator stator bar", which includes: (1) Test the glass transition temperature Tg0, heat distortion temperature THDT0 and tensile strength Sp0 of the main insulation material of the stator bar; (2) Measure the interlayer adhesion strength Plbl0 of the mica tape in the main insulation of the stator bar; (3) Swell the main insulation sample with a solvent, and then test the glass transition temperature Tg1, heat distortion temperature THDT1 and tensile strength Sp1 of the sample after being soaked and swollen by the solvent; (4) Perform an interlayer adhesion strength test on the main insulation sample after being soaked and swollen by the solvent to obtain the adhesion strength Plbl1; (5) Calculate the curing degree Cure% of the main insulation material of the stator bar using a formula, etc. Summary of the Invention

[0005] The present invention analyzes the uncrosslinked and uncured components of the insulation of the generator stator winding. First, it characterizes their molecular structures, and then studies their physical and chemical properties, and finds that their thermal weight loss behaviors are significantly different from those of the resin after complete crosslinking and curing; in addition, solvents with specific solubility parameters have extremely high solubility in these uncrosslinked and uncured components at appropriate temperatures, while the completely crosslinked and cured resin cannot be dissolved in this solvent;

[0006] Based on this, the inventors utilized these differences to design a suitable experimental method, determined the corresponding key parameters, which can reflect the overall content of the resin in the insulation of the generator stator winding from different angles, as well as the respective contents of the uncrosslinked and uncured components and the completely crosslinked and cured components therein, and proposed an evaluation method applicable to the crosslinking and curing degree of the insulation of the generator stator winding.

[0007] In order to achieve the above technical objectives, the following technical solutions are proposed:

[0008] An evaluation method applicable to the crosslinking and curing degree of the insulation of the generator stator winding, comprising the following steps:

[0009] Test the thermal weight loss curve of the insulation sample of the stator winding at a heating rate of k1, and obtain the residual mass W of the insulation sample of the stator winding when the test temperature rises to T1 T1 , and obtain the residual mass W when the test temperature rises to T2 T2 ;

[0010] Test the initial weight W of the insulation sample of the stator winding S0 , immerse the insulation sample of the stator winding in the solvent S at a certain temperature T s , and control it to be fully immersed; then, take it out of this solvent, thoroughly dry it, and weigh it, and record the weight of the insulation sample of the stator winding at this time as W S1 , and record the solubility parameter of the solvent S as SP S . Among them, the solvent S can fully immerse the insulation sample of the stator winding at the temperature T s , and has extremely strong solubility in the resin components that are not fully crosslinked and cured, and can ensure that after the solvent immersion treatment, the uncrosslinked and uncured resin components inside the insulation sample of the stator winding are completely removed;

[0011] Calculate the crosslinking and curing degree parameter D of the insulation of the stator winding crosslinking , ensuring high test accuracy and being able to well reflect the crosslinking and curing degree of the insulation of the stator winding. The calculation formula is as follows in formula (1):

[0012]

[0013] Further, the test method of the thermogravimetric curve is carried out according to the national standard "GB / T 27761-2011 Test Method for Weight Loss and Residual Amount of Thermogravimetric Analyzer".

[0014] Further, during the thermogravimetric test, the heating rate k1 is 0.1-40 °C / min, preferably 1-20 °C / min.

[0015] Further, the thermogravimetric test temperature T1 is 30-300 °C, preferably 50-250 °C; the thermogravimetric test temperature T2 is 250-1000 °C, preferably 300-800 °C.

[0016] Further, the initial weight W of the stator winding insulation sample subjected to the soaking treatment S0 is 0.001-10 kg, preferably 0.05-1 kg.

[0017] Further, the solvent S is one or any combination of two or more of pentane, tetrahydrofuran, isobutyl acetate, methylcyclohexane, 1,2-dichloroethane, turpentine, n-octanol, methyl isobutyl ketone, isobutanol, dimethylacetamide, carbon tetrachloride, isopropanol, dimethyl ether, dimethyl sulfoxide, tetralin, n-hexane, diethyl ether, acetone, cyclohexanone, cyclohexane, amyl acetate, n-hexanol, cresol, cyclohexanol, n-butanol, xylene, acetic acid, ethanol, isobutene, n-heptane, chloromethane, ethyl isobutyrate, methyl pentyl acetate, 2,2-dichloropropane, butyl acetate, dipentene, pyridine, methyl isopropyl ketone, piperidine, n-propanol, toluene, formic acid, water, chloroform, phenol, glycerol and ethylene glycol.

[0018] Further, the solubility parameter SP of the solvent S s is its inherent characteristic parameter, which can be found in relevant materials; for the mixed solvent composed of n solvents numbered 1-n, the SP of the mixed solvent s is calculated according to the following formula (2):

[0019] SP s =(M ols1 ×SP s1 +M ols2 ×SP s2 +...+M olsn ×SP sn ) (2)

[0020] In the formula, M ols1 -M olsn are the molar percentages of the solvents numbered 1-n in the mixed solvent respectively, and SP s1 -SP sn are the solubility parameters of the solvents numbered 1-n respectively;

[0021] Furthermore, the soaking temperature Ts ≤ the boiling point of the solvent or mixed solvent.

[0022] Adopting this technical solution, the beneficial technical effects are as follows:

[0023] In the present invention, in order to improve the accuracy of the analysis technology, the inventor has carried out a large number of experimental studies, further designed a complete set of experimental methods and specific experimental conditions, and designed a special formula to ensure that the calculated results obtained can accurately reflect the crosslinking and curing degree of the sample to be tested. Finally, the parameter Dcrosslinking reflecting the crosslinking and curing degree is obtained. Among them, using this formula can calculate the parameter reflecting the crosslinking and curing degree of the generator stator winding. Compared with the traditional characterization method, the present invention has high accuracy, and the testing process is fast, simple and easy to implement;

[0024] The present invention innovatively proposes to analyze the structural characteristics of the insulation material of the generator stator winding, and finds that its uncrosslinked and uncured components are mainly small molecule monomers, additives such as crosslinking agents and accelerators, as well as incompletely crosslinked oligomers and oligomers with linear molecular backbones. By designing corresponding analysis methods, obtaining relevant parameters, and designing a formula to calculate the parameter reflecting the crosslinking and curing degree of the insulation material of the generator stator winding, the accurate and rapid evaluation of its crosslinking and curing degree can be realized. Specific Embodiments

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] The following embodiments start from the characteristics of the organic / inorganic composite material of the generator stator winding insulation, and consider that the generator stator winding insulation is a composite material composed of inorganic components such as glass fiber and mica and thermosetting resin. Among them, the crosslinking and curing degree mainly refers to the crosslinking degree of the thermosetting resin of the stator winding insulation. Further, around the difficult problem of accurately evaluating its crosslinking and curing degree, through years of research and exploration, it is found that if the crosslinking and curing degree of the generator stator winding insulation is different, the thermal weight loss behavior of the resin is also significantly different; at the same time, under the action of a solvent with a specific solubility parameter, the solubility of the uncrosslinked and uncured part in the stator winding insulation is high, while the completely crosslinked and cured resin cannot be dissolved in this solvent. Based on this, the inventor innovatively proposed the present invention, which is significantly different from the research objects, involved indicators, achieved purposes and effects of the prior art (such as CN111505459A, CN101132140, etc.). Therefore, the following specific examples are proposed to further illustrate this technical solution.

[0027] In the following embodiments, the solvents involved and the corresponding solubility parameters SP s are shown in Table 1 below:

[0028] Table 1 Solvents and the corresponding solubility parameters SP s

[0029]

[0030] Example 1

[0031] 1. Test the thermogravimetric curves of stator winding insulation samples A and B at a heating rate k1 = 1.5 °C / min, and obtain the residual mass W of the samples when the test temperature rises to T1 = 149 °C T1 which are 89 wt% and 95 wt% respectively, and the residual mass W when the test temperature rises to T2 = 800 °C T2 are both 70 wt%;

[0032] 2. Test the initial weights W of stator winding insulation samples A and B S0 = 0.1 kg, and then immerse them in the solvent n-propanol at a temperature T s = 58 ± 1 °C to ensure that they are fully immersed; then, take them out of the solvent, thoroughly dry them and weigh them, and record the weight W of the sample at this time S1 which are 0.077 kg and 0.089 kg respectively. By referring to relevant materials, the solubility parameter SP of this solvent S = 11.9 (cal / cm 3 ) 1 / 2 ;

[0033] 3. Calculate the crosslinking and curing degree parameter D of the stator winding insulation according to the formula crosslinking . The test accuracy of the method of the present invention is high and can well reflect the crosslinking and curing degree of the stator winding insulation. The calculation formula is as follows:

[0034]

[0035] Calculate the D of samples A and B crosslinking which are 61.6% and 55.5% respectively.

[0036] Reference comparison method: Using the equilibrium swelling method to measure the crosslinking density, calculate the crosslinking and curing degree of the main insulation. First, use the equilibrium swelling method described in the literature "Lin Li, Zhang Hong, Li Yuan, Zhang Hua. Research progress on the test methods of crosslinking density of thermosetting polymers. Thermosetting Resin. 2012, 27(05): 60-63". Calculate the crosslinking density of the fully cured main insulation (providing sufficient curing time and curing temperature to make the curing reaction proceed fully and completely) and the uncured main insulation sample, denoted as DL-100% and DL-0% respectively. Then measure the crosslinking density of the sample to be tested, denoted as DL-to be tested. Use the following formula to calculate the crosslinking and curing degree Dcl (swelling method) of the sample to be tested:

[0037]

[0038] The crosslinking and curing degrees Dcl (swelling method) of sample A and sample B calculated by the above formula are 61.7% and 55.4% respectively. Then, use the curing degree parameter D obtained by the method proposed in the present invention crosslinking Compare with the result of Dcl (swelling method), and find that the two are very close, indicating that the calculation result of the present invention is accurate.

[0039] Example 2

[0040] 1. Test the thermogravimetric curves of the stator winding insulation samples C and D at a heating rate k1 = 5 °C / min, and obtain the residual mass W of the sample when the test temperature rises to T1 = 244 °C T1 which are 68wt% and 79wt% respectively, and the residual mass W of the sample when the test temperature rises to T2 = 690 °C T2 are both 55wt%;

[0041] 2. Test the initial weights W of the stator winding insulation samples C and D S0 = 0.5 kg, and then immerse them in a mixed solvent of n-heptane / turpentine (molar ratio of n-heptane:turpentine is 1:1) at a temperature T s = 61 ± 2 °C, and ensure that they are fully immersed; then, take them out of the solvent, thoroughly dry them and weigh them, and record the weight W of the sample at this time S1 which are 0.47 kg and 0.39 kg respectively. After consulting relevant materials and using the following formula to calculate the solubility parameter SP of the mixed solvent S = 7.75 (cal / cm 3 ) 1 / 2 ;

[0042] SP s = (M ols1 × SP s1 + M ols2 × SP s2 +... + Molsn ×SP sn )

[0043] 3. Calculate the crosslinking and curing degree parameter D of the stator winding insulation according to the formula crosslinking , the method of the present invention has high test accuracy and can well reflect the crosslinking and curing degree of the stator winding insulation. Its calculation formula is as follows:

[0044]

[0045] Calculate D of sample C and sample D crosslinking They are 19.3% and 45.2% respectively.

[0046] Reference comparison method: Use the method of measuring crosslinking density by equilibrium swelling method to calculate the crosslinking and curing degree of the main insulation. First, use the equilibrium swelling method described in the literature "Lin Li, Zhang Hong, Li Yuan, Zhang Hua. Research progress on the test methods of crosslinking density of thermosetting polymers. Thermosetting Resin. 2012, 27(05): 60 - 63". Calculate the crosslinking density of the fully cured main insulation (providing sufficient curing time and curing temperature to make the curing reaction proceed fully and completely) and the uncured main insulation sample, and record them as DL - 100% and DL - 0% respectively. Then measure the crosslinking density of the sample to be tested and record it as DL - to be tested. Use the following formula to calculate the crosslinking and curing degree Dcl (swelling method) of the sample to be tested:

[0047]

[0048] The crosslinking and curing degrees Dcl (swelling method) of sample A and sample B calculated by the above formula are 19.1% and 45.0% respectively. Then, use the curing degree parameter D obtained by the method proposed by the present invention crosslinking Compare with the result of Dc (swelling method), and it is found that the two are very close, indicating that the calculation result of the present invention is accurate.

[0049] Example 3

[0050] 1. Test the thermogravimetric curves of the stator winding insulation samples E and F at a heating rate k1 = 12 °C / min, and obtain the residual mass W of the sample when the test temperature rises to T1 = 186 °C T1 They are 72wt% and 63wt% respectively, and the residual mass W when the test temperature rises to T2 = 750 °C T2 are both 49wt%;

[0051] 2. Test the initial weight W of the stator winding insulation samples E and F S0 = 0.2 kg, and then place them at temperature T sSoak it in a mixed solvent of ethanol / diethyl ether / isobutanol (molar ratio of ethanol:diethyl ether:isobutanol is 2:1:1) at 15±0.5 °C, and ensure that it is fully soaked; then, take it out of the solvent, thoroughly dry it and weigh it, and record the weight W of the sample at this time S1 They are 0.19 kg and 0.166 kg respectively. After consulting relevant materials and calculating with the following formula, the solubility parameter SP of this mixed solvent is obtained S = 11.9 (cal / cm 3 ) 1 / 2 ;

[0052] SP s = (M ols1 ×SP s1 + M ols2 ×SP s2 +... + M olsn ×SP sn )

[0053] 3. Calculate the crosslinking and curing degree parameter D of the stator winding insulation according to the formula crosslinking , the method of the present invention has high test accuracy and can well reflect the crosslinking and curing degree of the stator winding insulation. Its calculation formula is as follows:

[0054]

[0055] Calculate D of sample E and sample F crosslinking They are 28.3% and 34.3% respectively.

[0056] Reference comparison method: Use the method of measuring crosslinking density by equilibrium swelling method to calculate the crosslinking and curing degree of the main insulation. First, use the equilibrium swelling method described in the literature "Lin Li, Zhang Hong, Li Yuan, Zhang Hua. Research progress on the test method of crosslinking density of thermosetting polymers. Thermosetting Resin. 2012, 27(05): 60-63". Calculate the crosslinking density of the fully cured main insulation (providing sufficient curing time and curing temperature to make the curing reaction proceed fully and completely) and the uncured main insulation sample, and record them as DL-100% and DL-0% respectively. Then measure the crosslinking density of the sample to be measured, and record it as DL-to be measured. Use the following formula to calculate the crosslinking and curing degree Dcl (swelling method) of the sample to be measured:

[0057]

[0058] The crosslinking and curing degrees Dcl (swelling method) of sample E and sample F calculated by the above formula are 28.5% and 34.4% respectively. Then, compare the curing degree parameter D crosslinking obtained by the method proposed by the present invention with the result of Dc (swelling method), and it is found that the two are very close, indicating that the calculation result of the present invention is accurate.

[0059] Example 4

[0060] 1. Test the thermogravimetric curves of stator winding insulation samples G and H at a heating rate k1 = 20 °C / min, and obtain the residual mass W of the samples when the test temperature rises to T1 = 231 °C T1 which are 88 wt% and 96 wt% respectively, and the residual mass W when the test temperature rises to T2 = 400 °C T2 are both 75 wt%;

[0061] 2. Test the initial weights W of stator winding insulation samples G and H S0 = 1 kg, and then immerse them in the solvent phenol at a temperature T s = 90 ± 1.5 °C and ensure that they are fully immersed; then, take them out of the solvent, thoroughly dry them and weigh them, and record the weight W of the specimen at this time S1 which are 0.82 kg and 0.88 kg respectively. After consulting relevant materials, the solubility parameter SP of this solvent S = 14.5 (cal / cm 3 ) 1 / 2 ;

[0062] 3. Calculate the crosslinking and curing degree parameter D of the stator winding insulation according to the formula crosslinking , the test accuracy of the method of the present invention is high, and it can well reflect the crosslinking and curing degree of the stator winding insulation. The calculation formula is as follows:

[0063]

[0064] It is calculated that the Dcrosslinking of samples G and H are 54.6% and 60.6% respectively.

[0065] Reference comparison method: Use the method of measuring crosslinking density by equilibrium swelling method to calculate the crosslinking and curing degree of the main insulation. First, use the equilibrium swelling method described in the literature "Lin Li, Zhang Hong, Li Yuan, Zhang Hua. Research progress on the test methods of crosslinking density of thermosetting polymers. Thermosetting Resin. 2012, 27(05): 60-63". Calculate the crosslinking density of the fully cured main insulation (providing sufficient curing time and curing temperature to make the curing reaction proceed fully and completely) and the uncured main insulation specimen, and record them as DL-100% and DL-0% respectively. Then measure the crosslinking density of the sample to be tested, and record it as DL-tested. Use the following formula to calculate the crosslinking and curing degree Dcl (swelling method) of the sample to be tested:

[0066]

[0067] The crosslinking and curing degrees Dc (swelling method) of sample G and sample H calculated by the above formula are 54.9% and 60.2% respectively. Then, the curing degree parameter D obtained by using the method proposed in the present invention crosslinking is compared with the result of Dcl (swelling method), and it is found that the two are very close, indicating that the calculation result of the present invention is accurate.

[0068] Based on Examples 1-4, the key parameters and results involved are summarized in Table 2 below.

[0069] Table 2 List of Key Parameters of Specific Embodiments

[0070]

Claims

1. An evaluation method applicable to the insulation cross-linking and curing degree of a generator stator winding, characterized in that It includes the following steps: Test the thermogravimetric curve of the stator winding insulation sample at the heating rate k 1 to obtain the residual mass of the stator winding insulation sample when the test temperature rises to T 1 ; and obtain the residual mass when the test temperature rises to W T1 ; and obtain the residual mass when the test temperature rises to T 2 ; W T2 ; During the thermogravimetric test, the heating rate k 1 is 0.1 - 40 °C / min; the thermogravimetric test temperature T 1 is 30 - 300 °C; the thermogravimetric test temperature T 2 is 300 - 800 °C; Test the initial weight of the stator winding insulation sample W S0 , immerse the stator winding insulation sample in solvent S at a certain temperature T s , and control it to be fully immersed; then, take it out of the solvent, thoroughly dry it, weigh it, and record the weight of the stator winding insulation sample at this time as W S1 , and record the solubility parameter of solvent S as SP S ; Calculate the crosslinking and curing degree parameter D of the stator winding insulation crosslinking , and the calculation formula is as follows in formula (1): （1）。 2. The evaluation method for the insulation crosslinking and curing degree applicable to the generator stator winding according to claim 1, wherein The test method of the thermogravimetric curve is tested according to the national standard "GB / T 27761-2011 Test Method for Weight Loss and Residual Amount of Thermogravimetric Analyzer".

3. The evaluation method for the insulation crosslinking and curing degree of a generator stator winding according to claim 1, characterized in that, The initial weight of the stator winding insulation sample subjected to the soaking treatment W S0 is 0.001 - 10 kg.

4. The evaluation method for the insulation crosslinking and curing degree of a generator stator winding according to claim 1, characterized in that, The solvent S is one or any combination of two or more of pentane, tetrahydrofuran, isobutyl acetate, methylcyclohexane, 1,2-dichloroethane, turpentine, n-octanol, methyl isobutyl ketone, isobutanol, dimethylacetamide, carbon tetrachloride, isopropanol, dimethyl ether, dimethyl sulfoxide, tetralin, n-hexane, diethyl ether, acetone, cyclohexanone, cyclohexane, amyl acetate, n-hexanol, cresol, cyclohexanol, n-butanol, xylene, acetic acid, ethanol, isobutene, n-heptane, chloromethane, ethyl isobutyrate, methyl pentyl acetate, 2,2-dichloropropane, butyl acetate, dipentene, pyridine, methyl isopropyl ketone, piperidine, n-propanol, toluene, formic acid, water, chloroform, phenol, glycerol and ethylene glycol.

5. The evaluation method for the insulation crosslinking and curing degree of a generator stator winding according to claim 1, wherein The solvent S is denoted as numbers 1 - n, where n represents the mixed solvent composed of n solvents. Then, for the mixed solvent, SP s it is calculated according to the following formula (2): （2） In the formula described, M ols1 - M olsn are the molar percentages of the solvents numbered 1 - n in the mixed solvent respectively, SP s1 - SP sn are the solubility parameters of the solvents numbered 1 - n respectively.

6. The evaluation method for the insulation crosslinking and curing degree of a generator stator winding according to claim 1, characterized in that Soaking temperature T s ≤ the boiling point of the solvent or mixed solvent.

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