A new method for determining the content of ATH in HTV silicone rubber

Abstract

The application discloses a novel ATH content determination method for HTV silicone rubber, which is high in determination accuracy, strong in reliability, simple in operation and free from damage to the silicone rubber material. The method comprises the following steps: obtaining silicone rubber samples with different ATH contents; performing terahertz time-domain spectrum testing on the silicone rubber samples with different ATH contents to obtain terahertz time-domain spectra of the silicone rubber samples with different ATH contents; performing transformation on the terahertz time-domain spectra of the silicone rubber samples with different ATH contents to obtain terahertz frequency-domain spectra of the silicone rubber samples with different ATH contents; obtaining a domain spectrum amplitude based on the terahertz frequency-domain spectra of the silicone rubber samples with different ATH contents and calculating dielectric constants; and establishing a relationship between the ATH content and the dielectric constant to realize quantitative determination of the ATH content.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-voltage insulating materials, in particular to a new ATH content determination method for HTV silicone rubber. BACKGROUND

[0002] Composite insulator is an important device of ultra / extra-high voltage transmission line, which plays an important role in electrical insulation and mechanical support in ultra / extra-high voltage transmission line. High temperature vulcanization (HTV) silicone rubber is the most commonly used umbrella sleeve material of composite insulator, and its performance stability determines the operation reliability of the composite insulator. Among them, the arc resistance of HTV silicone rubber is the key to avoid external insulation flashover, which is directly related to the safety of power system operation.

[0003] Adding ATH filler is a common method to improve the arc resistance of silicone rubber in the industry, and the content of which will have a great impact on the performance of silicone rubber. Studies have shown that adding an appropriate amount of ATH can significantly improve the tracking resistance, arc resistance and arc resistance of silicone rubber. However, when the ATH content is too high, not only will it reduce the tracking resistance of silicone rubber, but also will reduce the mechanical properties of the material. Therefore, the electrical properties and mechanical properties of silicone rubber are closely related to the ATH content.

[0004] At present, there is a lack of determination method for ATH content in HTV silicone rubber. The thermal analysis method based on the thermal gravimetric curve proposed in recent years lacks practical application and is destructive, and the non-destructive testing of component content in silicone rubber is still a technical problem faced by the power industry. Therefore, developing a new non-destructive determination method with high accuracy and simple operation has become a key problem to be solved in the field of composite insulators. SUMMARY

[0005] The purpose of the present application is to provide a new ATH content determination method for HTV silicone rubber, to overcome the defects of the prior art, the present application has high determination accuracy, high reliability and simple operation, and will not damage the silicone rubber material.

[0006] The present application is achieved by the following technical solutions:

[0007] A new ATH content determination method for HTV silicone rubber, comprising the following steps:

[0008] Obtain silicone rubber samples with different ATH contents;

[0009] Perform terahertz time domain spectrum test on the silicone rubber samples with different ATH contents to obtain the terahertz time domain spectrum of the silicone rubber samples with different ATH contents;

[0010] Transform the terahertz time domain spectrum of the silicone rubber samples with different ATH contents to obtain the terahertz frequency domain spectrum of the silicone rubber samples with different ATH contents;

[0011] Based on the terahertz frequency domain spectrum of the silicone rubber sample with different ATH content, the domain spectrum amplitude is obtained and the dielectric constant is calculated;

[0012] The relationship between the ATH content and the dielectric constant is established to realize quantitative determination of the ATH content.

[0013] Preferably, the silicone rubber sample with different ATH content comprises:

[0014] The random cutting part of the silicone rubber insulator is taken as the silicone rubber sample, wherein the thickness of the cutting part is not less than 1mm.

[0015] Preferably, the information of the terahertz time domain spectrum comprises:

[0016] The phase of the reference signal, the amplitude of the reference signal and the frequency information of the reference signal;

[0017] And the phase of the sample signal, the amplitude of the sample signal and the frequency information of the sample signal.

[0018] Preferably, the terahertz time domain spectrum of the silicone rubber sample with different ATH content is transformed to obtain the terahertz frequency domain spectrum of the silicone rubber sample with different ATH content, wherein the fast Fourier transform is used to obtain the terahertz frequency domain spectrum from the terahertz time domain spectrum.

[0019] Preferably, the terahertz frequency domain spectrum of the silicone rubber sample with different ATH content comprises:

[0020] According to the amplitude information in the terahertz frequency domain spectrum, the position of the ATH characteristic peak in the HTV silicone rubber is determined;

[0021] According to the position and amplitude information of the ATH characteristic peak, the characteristic peak area is obtained and the relationship between the characteristic peak area and the ATH content is determined.

[0022] Preferably, the position of the ATH characteristic peak is 1.2THz and 1.33THz.

[0023] Preferably, the calculation of the dielectric constant comprises:

[0024] The refractive index and the extinction coefficient are obtained by processing the terahertz frequency domain spectrum;

[0025] Based on the refractive index and the extinction coefficient, the real part of the dielectric constant and the imaginary part of the dielectric constant in the terahertz domain are calculated according to the Maxwell electromagnetic field theory equation.

[0026] Preferably, the expression of the refractive index is:

[0027]

[0028] wherein n s n(ω) is the refractive index, φ(ω) is the transfer function argument, ω is the frequency, c is the vacuum light speed, and d is the sample thickness.

[0029] Preferably, the expression of the extinction coefficient is:

[0030]

[0031] wherein κ s n(ω) is the extinction coefficient, n s n(ω) is the refractive index, ω is the frequency, c is the vacuum light speed, and d is the sample thickness.

[0032] Preferably, the relationship between the ATH content and the dielectric constant is:

[0033] y = 0.00704x - 0.000785

[0034] wherein y is the sum of the dielectric constant imaginary part of the characteristic peak after deducting the baseline, and x is the ATH content.

[0035] Compared with the prior art, the present application has the following beneficial technical effects:

[0036] The present application designs a new ATH content determination method for HTV silicone rubber, based on the terahertz time-domain spectroscopy technology, by measuring the terahertz time-domain spectrogram of the silicone rubber sample and the terahertz frequency domain spectrogram obtained by conversion, the amplitude of the ATH in the silicone rubber is obtained based on the optical and electromagnetic calculation, so as to evaluate the amount of the ATH content in the silicone rubber. Since the dielectric constant imaginary part is a characteristic parameter of the material and is not disturbed by uncertain factors such as test environment, the present application adopts this characteristic parameter which is accurate and universal, the relationship between the dielectric constant and the ATH content is constructed by calculation, the determination result is accurate, the reliability of the result is improved, and the operation is simple, non-destructive and accurate. The present application can be used for controlling and improving the ATH content, detecting the quality of the goods of the silicone rubber manufacturer or providing the life evaluation basis for the aging of the silicone rubber, etc. Because it has the advantages of non-destructive, high signal-to-noise ratio, strong reliability, convenience and speed, it is expected to be widely used in actual power grid operation. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creating any creative labor.

[0038] Figure 1A schematic diagram of a transmission type terahertz time domain spectrum in an embodiment of the present application;

[0039] Figure 2 A terahertz time domain spectrum in an embodiment of the present application;

[0040] Figure 3a A frequency domain spectrum in an embodiment of the present application;

[0041] Figure 3b A spectrum amplitude difference graph in an embodiment of the present application;

[0042] Figure 4 A graph of the relationship between ATH content and spectrum characteristic peak area in an embodiment of the present application;

[0043] Figure 5a A schematic diagram of the real part of the dielectric constant in the terahertz domain of silicone rubber in an embodiment of the present application;

[0044] Figure 5b A schematic diagram of the imaginary part of the dielectric constant in the terahertz domain of silicone rubber in an embodiment of the present application;

[0045] Figure 6 A fitting graph of the relationship between ATH content and the size of the imaginary part of the dielectric constant of the loss peak after deducting the baseline in an embodiment of the present application.

[0046] Figure 7 A flowchart of the method for determining the ATH content in the novel HTV silicone rubber of the present application.

[0047] In the figure, 1 is a sapphire femtosecond laser, 2 is a terahertz detection device, 3 is an electrically driven translation stage, 4 is a beam splitter prism, and 5 is a sample stage. DETAILED DESCRIPTION

[0048] The present application will be further described in detail below, which is an explanation rather than a limitation of the present application.

[0049] The present application provides a method for determining the ATH content in a novel HTV silicone rubber, as shown in the figure, comprising the following steps: Figure 7

[0050] Obtaining silicone rubber samples with different ATH contents;

[0051] Performing terahertz time domain spectrum testing on the silicone rubber samples with different ATH contents to obtain the terahertz time domain spectra of the silicone rubber samples with different ATH contents;

[0052] Transforming the terahertz time domain spectra of the silicone rubber samples with different ATH contents to obtain the terahertz frequency domain spectra of the silicone rubber samples with different ATH contents;

[0053] Based on the terahertz frequency domain spectra of the silicone rubber samples with different ATH contents, obtaining the domain spectrum amplitude and calculating the dielectric constant;​

[0054] The relationship between ATH content and dielectric constant is established to realize quantitative determination of ATH content.

[0055] Embodiment

[0056] Specifically, the ATH content determination method of the present application has the following implementation steps:

[0057] 1) A new method for determining the ATH content in silicone rubber uses a CIP-TDS terahertz time-domain spectroscopy system produced by Da Heng Optoelectronics. The system is composed of a sapphire femtosecond laser 1, a terahertz detection device 2, an ESP301 type electric translation stage 3 (time delay control), a beam splitter prism 4, a sample stage 5, and a software control system. The sample is installed on the sample stage 5. The principle is shown in Figure 1 The femtosecond laser generated by the sapphire femtosecond laser 1 is split into two paths by the beam splitter prism 4, one as the pump light and the other as the probe light. The pump light is focused onto the photoconductive antenna to generate terahertz waves. The generated terahertz waves pass through the optical system composed of off-axis mirrors and then converge with the probe light. The terahertz waves are detected by the probe light and recorded by the terahertz detection device 2. The time delay between the pump pulse and the probe pulse is adjusted by the time delay system composed of the high-precision electric translation stage 3, and finally the entire time-domain waveform of the terahertz pulse can be detected.

[0058] 2) A part of the silicone rubber insulator is randomly cut, with a size of 2 cm x 2 cm and a thickness of more than 1 mm to eliminate the influence of the Fabry-Perot effect;

[0059] 3) The humidity is maintained below 3%, and the reference signal and the sample signal are tested three times respectively and averaged to eliminate moisture interference and measurement error;

[0060] 4) The terahertz time-domain spectra of different ATH contents are obtained, as shown in Figure 2 The terahertz time-domain spectrum information includes the phase, amplitude, and frequency information of the reference signal and the phase, amplitude, and frequency information of the sample signal;

[0061] 5) The terahertz time-domain spectrum is subjected to fast Fourier transform to obtain the terahertz frequency-domain spectrum, as shown in Figure 3a The terahertz frequency-domain spectrum information includes the amplitude information and frequency information of the reference signal and the amplitude information and frequency information of the sample signal, and the amplitude difference is shown in Figure 3b The sample signal is divided by the reference signal to obtain the transfer function of the sample;

[0062] 6) According to the amplitude information in the terahertz frequency-domain spectrum in 5), the ATH characteristic peaks in HTV silicone rubber are determined to be 1.2 THz and 1.33 THz, which are respectively derived from the free hydroxyl group and the associated hydroxyl group of ATH;

[0063] 7) Comparing the position and area of the characteristic peak in 6), it can be confirmed that the relationship between the area of the characteristic peak and the ATH content, as shown in Figure 4 The higher the ATH content, the larger the characteristic peak area.

[0064] 8) Further processing by terahertz frequency domain spectrum, the refractive index and extinction coefficient in the terahertz field are obtained, as shown in the formula: Where n s (ω) is the refractive index, φ(ω) is the transfer function amplitude angle, ω is the frequency, c is the speed of light in vacuum, d is the sample thickness, and A(ω) is the transfer function amplitude.

[0065] 9) Using the refractive index and extinction coefficient, the real part of the dielectric constant and the imaginary part of the dielectric constant in the terahertz field are obtained according to the Maxwell electromagnetic field theory equation, as shown in the formula: Figure 5a And Figure 5b As shown in the formula:

[0066]

[0067]

[0068] 10) The amplitude change of the real part of the dielectric constant in the abnormal dispersion region after processing is positively correlated with the ATH content. The real part of the dielectric constant increases, and the imaginary part of the dielectric constant in the abnormal dispersion region also increases, which is mainly due to the ionic displacement polarization of the associated hydroxyl and free hydroxyl in ATH.

[0069] 11) The sum of the imaginary part of the dielectric constant of the characteristic peaks at 1.2 THz and 1.33 THz in the terahertz spectrum and the ATH content show strong correlation, and the ATH content detection formula is obtained by linear fitting, as shown in the formula: Figure 6

[0070] y = 0.00704x - 0.000785.

[0071] y is the sum of the characteristic peak dielectric constant imaginary part after deducting the baseline, x is the ATH content, and the goodness of fit is 0.9998. The present application proposes to use the sum of the ATH characteristic peak values at 1.2 THz and 1.33 THz as a new means to evaluate the ATH content in HTV silicone rubber, which has the advantages of non-destructive, convenient, high signal-to-noise ratio, and strong reliability.

[0072] ​The present application is based on terahertz time-domain spectroscopy technology, and is a novel method for evaluating ATH content in HTV silicone rubber. The present application measures the terahertz spectrum of a silicone rubber sample, obtains the characteristic fingerprint peak of ATH in the silicone rubber through fast Fourier transform and optical and electromagnetic operations, and evaluates the amount of ATH content in the silicone rubber. Since the imaginary part of the dielectric constant is a characteristic parameter of the material and is not disturbed by uncertain factors such as the test environment, the characteristic parameter is accurate and universal. The present application can be used to control and improve the ATH content, detect the quality of goods of a silicone rubber manufacturer, or provide a life evaluation basis for the aging of silicone rubber, and has the advantages of non-destructive, high signal-to-noise ratio, high reliability, convenience, and rapidness, and is expected to be widely used in actual power grid operation.

[0073] The above example details the core operation process of the present application. The example is only one of the various embodiments of the present application, and the content shown in the drawing is also only one of the embodiments of the present application. The actual content of the present application is not limited thereto. For the implementation of the present application, without departing from the core idea of the present application, similar structural schemes or implementation cases to the present application can be designed without the permission of the creator, and all should belong to the protection scope of the present application.

[0074] The basic principles and main features of the present application and the advantages of the present application are shown and described above, and it is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or basic characteristics of the present application. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0075] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be properly combined to form other embodiments that those skilled in the art can understand. The above content only illustrates the technical idea of the present application, and cannot limit the protection scope of the present application, and any modification made on the basis of the technical solutions according to the present application falls within the protection scope of the claims of the present application.

Claims

1. A novel method for determining the ATH content in HTV silicone rubber, characterized in that: The steps include: Obtain silicone rubber samples with different ATH contents; The terahertz time-domain spectroscopy test was performed on silicone rubber samples with different ATH contents to obtain the terahertz time-domain spectra of the silicone rubber samples with different ATH contents. The terahertz time domain spectra of the silicone rubber samples with different ATH contents are transformed to obtain the terahertz frequency domain spectra of the silicone rubber samples with different ATH contents; Based on the terahertz frequency domain spectra of silicone rubber samples with different ATH contents, the domain spectrum amplitude was obtained and the dielectric constant was calculated; Establish the relationship between ATH content and dielectric constant to achieve quantitative determination of ATH content; The calculation of the dielectric constant includes: The refractive index and extinction coefficient are obtained by processing the terahertz frequency domain spectrum; Based on the refractive index and extinction coefficient, the real part and imaginary part of the dielectric constant in the terahertz domain are calculated according to Maxwell's electromagnetic field theory equations. The expression of the extinction coefficient is: Where, is the extinction coefficient, is the refractive index, ω is the frequency, is the speed of light in vacuum, is the sample thickness, is the transfer function amplitude; The transfer function establishment process is as follows: performing fast Fourier transform on the terahertz time domain spectrum to obtain a terahertz frequency domain spectrum, wherein the terahertz frequency domain spectrum information includes the amplitude information and frequency information of the reference signal and the amplitude information and frequency information of the sample signal; dividing the sample signal by the reference signal to obtain the transfer function of the sample; The ATH content is linearly related to the sum of the imaginary parts of the dielectric constants of the characteristic peaks after deducting the baseline.

2. The method for determining the ATH content in a novel HTV silicone rubber according to claim 1, characterized in that: The obtaining of silicone rubber samples with different ATH contents comprises: Randomly cut out parts of the silicone rubber insulator as silicone rubber samples, wherein the thickness of the cut part is not less than 1mm.

3. The method for determining the ATH content in a novel HTV silicone rubber according to claim 1, characterized in that: The information of the terahertz time domain spectrum includes: Phase of the reference signal, amplitude of the reference signal, and frequency information of the reference signal; As well as the phase of the sample signal, the amplitude of the sample signal and the frequency information of the sample signal.

4. The method for determining the ATH content in a novel HTV silicone rubber according to claim 1, characterized in that: In the process of transforming the terahertz time domain spectra of the silicone rubber samples with different ATH contents to obtain the terahertz frequency domain spectra of the silicone rubber samples with different ATH contents, the terahertz time domain spectra are transformed using fast Fourier transform to obtain the terahertz frequency domain spectra.

5. The method for determining the ATH content in a novel HTV silicone rubber according to claim 1, characterized in that: The terahertz frequency domain spectrum of the silicone rubber samples with different ATH contents, and obtaining the domain spectrum amplitude includes: The position of the ATH characteristic peak in HTV silicone rubber is determined based on the amplitude information in the terahertz frequency domain spectrum; According to the position and amplitude information of the ATH characteristic peak, the characteristic peak area is obtained and the relationship between the characteristic peak area and the ATH content is determined.

6. The method for determining the ATH content in a novel HTV silicone rubber according to claim 5, wherein: The positions of the ATH characteristic peaks are 1.2 THz and 1.33 THz.

7. The method for determining the ATH content in a novel HTV silicone rubber according to claim 1, characterized in that: The expression of the refractive index is: Where, is the refractive index, is the transfer function angle, ω is the frequency, is the speed of light in vacuum, is the sample thickness.

8. The method for determining the ATH content in a novel HTV silicone rubber according to claim 1, characterized in that: The relationship between the ATH content and the dielectric constant is: Where, is the sum of the imaginary parts of the dielectric constants of the characteristic peaks after deducting the baseline. ATH content.

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