CN103884918B - Method for detecting aging degree of zinc oxide arrester resistor disc - Google Patents

Abstract

A detection method aimed at the aging degree of zinc oxide arrester resistors, comprising the steps of: cutting the resistors to be tested into at least 5 equal parts on average along the direction perpendicular to the current; respectively testing the dielectric properties of several slices obtained in the previous steps; The imaginary part of the permittivity εˊˊ of the slice is the ordinate, and the frequency f is the abscissa, and the change law of the imaginary part of the permittivity εˊˊ with the frequency f at different temperatures is obtained, and the relaxation activation energy value corresponding to each loss peak is calculated according to the Arrhenius formula According to the relaxation activation energy, the defects corresponding to the loss peaks are oxygen vacancies and zinc interstitial intrinsic defects; the loss peak-to-peak comparison of the dielectric spectrum εˊˊ～f of each slice at -100 ° C is obtained to obtain the oxygen vacancies in the resistor. The distribution of the two intrinsic defect concentrations of vacancies and zinc interstitials in the current direction, and the aging degree of the resistor can be judged according to the change rate of the zinc interstitial defect concentration. The invention can more accurately detect the aging degree of the resistance sheet of the zinc oxide arrester from a microcosmic perspective.

Description

A detection method for the aging degree of zinc oxide arrester resistors

【Technical field】

The invention belongs to the technical field of resistance plates of zinc oxide arresters, and in particular relates to a detection method for the aging degree of resistance plates of zinc oxide arresters.

【Background technique】

Zinc oxide varistor ceramics use zinc oxide as the main raw material, adding about 10% additive raw materials as doping additives, such as Bi ₂ O ₃ , Co ₂ O ₃ (Co ₃ O ₄ ), MnO ₂ (MnCO ₃ ), Sb ₂ O ₃ , SiO ₂ and Cr ₂ O ₃ etc. are prepared by ceramic sintering process. Due to its good nonlinearity and large flow capacity, zinc oxide arresters have been widely used in power systems. Due to long-term exposure to working voltage and overvoltage, the performance of zinc oxide arrester resistors will gradually deteriorate or even fail. Therefore, effective evaluation of the aging degree of zinc oxide arrester resistors is a key issue in the practical application of zinc oxide arresters.

So far, people have carried out relevant research on the aging characteristics of zinc oxide arrester resistors. Most of the research focuses on the overall electrical performance, but the factory value is unknown from time to time, which makes it more difficult to measure the aging degree of zinc oxide arrester resistors.

【Content of invention】

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a detection method for the aging degree of the resistive sheet of the zinc oxide arrester.

To achieve the above object, the present invention adopts the following technical solutions:

A method for detecting the aging degree of a zinc oxide surge arrester resistor, comprising the following steps:

1) Cut the resistance sheet to be tested into at least 5 equal parts perpendicular to the current direction to obtain several slices parallel to the current direction;

2) Test the dielectric properties of several slices obtained in step 1) separately, wherein, when the temperature range is -130°C to 40°C, each slice is measured once at an interval of 10°C from low temperature to high temperature, and at the same time At one temperature, the frequency range is 10 ^-1 Hz to 10 ⁶ Hz, and each slice is measured once at a decreasing ratio of 1.5 times from high frequency to low frequency;

3) Through the measured data obtained in step 2), the imaginary part of the permittivity ε" of each slice is taken as the ordinate, and the frequency f is taken as the abscissa, and the imaginary part of the permittivity ε" is changed with the frequency f at different temperatures According to the Arrhenius formula, the relaxation activation energy value corresponding to each loss peak is calculated, and the defects corresponding to the loss peak are judged by the relaxation activation energy to be oxygen vacancies and zinc interstitial intrinsic defects respectively;

4) Compare the peak-to-peak loss of the dielectric spectrum ε"~f of each slice at -100°C to obtain the distribution of the two intrinsic defect concentrations in the resistor sheet in the direction of current, oxygen vacancies and zinc interstitials. The change rate k of the interstitial defect concentration is used to judge the aging degree of the zinc oxide arrester resistor. Among them, when 0<k≤20%, the zinc oxide arrester resistor is in the early aging stage, and when 20<k≤100%, the oxidation Zinc arrester resistors are in the middle stage of aging, and when k>100%, the zinc oxide arrester resistors are in the late aging stage.

The further improvement of the present invention is that in step 1), each slice is polished and cleaned with distilled water or alcohol as a cleaning solution, and cleaned 6 to 7 times with an ultrasonic cleaner, each time for 15 minutes; the slices are dried at 80°C and then sprayed with gold. electrodes for testing.

A further improvement of the present invention is that in step 3), the calculation formula of the relaxation activation energy u is as follows:

$\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&pi;\&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; u</span>}}{\mathrm{<span\; class="notranslate">\; k</span>}\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

where f _m is the frequency corresponding to the relaxation loss peak, in Hz;

T is the absolute temperature in K;

_τ0 is a constant independent of temperature;

u is the relaxation activation energy in eV;

k is Boltzmann's constant, and its value is 1.381×10 ^-23 J/K.

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

The invention analyzes the aging characteristics of the internal current direction by cutting the resistance sheet, and compared with the traditional overall performance research, the invention can more effectively judge the degradation degree of the resistance sheet. Specifically, the deterioration of zinc oxide arrester resistors is a grain boundary phenomenon, which is the result of ion migration in the depletion layer, so the present invention is based on the concentration change rate of zinc interstitial intrinsic defects on the internal current direction of zinc oxide resistors To judge the aging degree of resistors, this detection method can more accurately detect the aging degree of zinc oxide resistors from a microscopic point of view, so as to guide the preparation process of zinc oxide varistors, so that the material has higher anti-aging performance and more suitable for industrial applications.

【Description of drawings】

Figure 1 is a schematic diagram of the cutting method of the zinc oxide arrester resistor sheet;

Figure 2 is the dielectric spectrum of a slice at low temperature;

Fig. 3 is the peak change of the oxygen vacancy loss peak and the zinc interstitial loss peak of the new zinc oxide resistor slice;

Figure 4 is the peak change of the oxygen vacancy loss peak and the zinc interstitial loss peak of a certain zinc oxide resistor slice after being subjected to 2000 continuous lightning strikes;

Figure 5 shows the peak changes of the oxygen vacancy loss peak and the zinc interstitial loss peak of a zinc oxide resistor slice after 5 years of actual operation.

【detailed description】

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

Referring to Fig. 1 to Fig. 5, a kind of detection method for the aging degree of zinc oxide surge arrester resistor of the present invention comprises the following steps:

1) Cut the resistance sheet to be tested into at least 5 equal parts on average perpendicular to the current direction, and obtain several slices parallel to the current direction, as shown in Figure 1; it should be noted that after grinding the slices, distilled water or Alcohol is used as the cleaning solution, and it is cleaned 6 to 7 times with an ultrasonic cleaner, each time for 15 minutes; the slices are dried at 80°C and then sprayed with gold electrodes for testing. Consistent in slices.

2) Test the dielectric properties of several slices obtained in step 1) separately, wherein, when the temperature range is -130°C to 40°C, each slice is measured once at an interval of 10°C from low temperature to high temperature, and at the same time At one temperature, the frequency range is 10 ^-1 Hz to 10 ⁶ Hz, and each slice is measured once at a decreasing ratio of 1.5 times from high frequency to low frequency;

3) Through the measured data obtained in step 2), the imaginary part of the permittivity ε" of each slice is taken as the ordinate, and the frequency f is taken as the abscissa, and the imaginary part of the permittivity ε" is changed with the frequency f at different temperatures According to the Arrhenius formula, the relaxation activation energy value corresponding to each loss peak is calculated, in which the values corresponding to the low-frequency loss peak and high-frequency loss peak are 0.20-0.26eV, 0.31-0.39eV, and the corresponding loss peaks are judged by the relaxation activation energy. The defects are oxygen vacancies and zinc interstitial intrinsic defects, as shown in Figure 2; where the relaxation activation energy u is calculated as follows:

$\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&pi;\&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; u</span>}}{\mathrm{<span\; class="notranslate">\; k</span>}\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

where f _m is the frequency corresponding to the relaxation loss peak, in Hz;

T is the absolute temperature in K;

_τ0 is a constant independent of temperature;

u is the relaxation activation energy in eV;

k is Boltzmann's constant, and its value is 1.381×10 ^-23 J/K.

4) Compare the dielectric spectrum ε”～f of each slice at -100°C, and obtain the ε” peak intensity of the oxygen vacancy loss peak and zinc interstitial loss peak of different slices, and draw the oxygen vacancy loss peak and zinc interstitial loss peak The change curve of the ε" peak intensity of the loss peak in the direction of the current, and the distribution of the two intrinsic defect concentrations of oxygen vacancies and zinc interstitials in the resistor sheet in the direction of the current are obtained. The change rate k of the zinc oxide arrester resistor is used to judge the aging degree of the zinc oxide arrester resistor. Among them, when 0<k≤20%, the zinc oxide arrester resistor is in the early stage of aging, and when 20<k≤100%, the zinc oxide arrester resistor In the middle stage of aging, when k>100%, the zinc oxide arrester resistor is in the late aging stage, as shown in Figure 3 to Figure 5.

Example 1:

Select a new zinc oxide arrester resistor (marked as 1#) and a zinc oxide arrester resistor (marked as 2#) after 2000 continuous 8/20μs lightning strikes. These two zinc oxide resistor samples are from the same manufacturer products of the same model. The peak value of the lightning impulse current experienced by resistor 2# is the nominal discharge current value specified in GB11032-2010. The resistor 2# is in the middle of aging, and the leakage current is 28μA, which is greater than the factory value (6μA). Cut the 1# and 2# zinc oxide resistors to be tested, and the cutting method is shown in Figure 1. Figure 2 is the dielectric spectrum of a certain slice at low temperature. It can be observed that there are two loss peaks in the ε”～f characteristic curve. Calculated by the Arrhenius formula, for all slices of resistor 1# and 2#, the low frequency loss peak and The relaxation activation energies of the high-frequency loss peaks are about 0.35 eV and 0.21 kV, respectively, corresponding to the oxygen vacancy and zinc interstitial intrinsic defects.

Figure 3 is a comparison of the peak changes of the oxygen vacancy loss peak and the zinc interstitial loss peak obtained by comparing the ε”～f curve of the slice of resistor 1# at -100°C. It can be seen that before aging, the oxygen vacancy defects and zinc The concentration of interstitial defects has no obvious change in the current direction. Figure 4 is the peak change of the oxygen vacancy loss peak and the zinc interstitial loss peak obtained from the ε"～f curve of the slice of the comparative resistor 2# at -100 ° C. It can be seen that in the middle stage of aging, the concentration of oxygen vacancies and zinc interstitial intrinsic defects in the resistor chip changes monotonously in the direction of current, and the concentration change rate of zinc interstitial defects is 98%. Comparing Figure 3 and Figure 4, it can be seen that the change of zinc interstitial defect concentration can reflect the aging degree of the resistor.

Example 2:

The resistive sheet of the zinc oxide arrester that has been in operation for 5 years in the substation is selected for illustration. The resistor sheet is in the early stage of aging, the leakage current is 10μA, and the U _1mA value (5.03kV) is close to the factory value (5.02kV). Cut the zinc oxide resistor, and the cutting method is shown in Figure 1.

Calculated by the Arrhenius formula, it can be known that the relaxation activation energies of the low-frequency loss peak and high-frequency loss peak of all slices are about 0.37eV and 0.22kV, respectively, corresponding to the intrinsic defects of oxygen vacancies and zinc interstitials.

Figure 5 is a comparison of the peak changes of the oxygen vacancy loss peak and the zinc interstitial loss peak obtained by comparing the ε"~f curve of the slice at -100°C. It can be seen that the oxygen vacancy defect concentration in the resistor chip at the initial aging stage is in the direction of the current Be monotonically increasing, and the rate of change of zinc interstitial defect concentration is less (14.3%), and this is consistent with the fact that " resistor sheet is in the initial stage of aging ".Above implementation will help those skilled in the art to further understand the present invention, but Do not limit the present invention in any form.It should be noted that, for those of ordinary skill in the art, under the premise of not departing from the inventive concept, some deformations and improvements can also be made.These all belong to the protection scope of the present invention.

Claims (3)

1. A detection method for the aging degree of zinc oxide surge arrester resistance sheet, is characterized in that, comprises the following steps: 1) Cut the resistance sheet to be tested into at least 5 equal parts perpendicular to the current direction to obtain several slices parallel to the current direction; 2) Test the dielectric properties of several slices obtained in step 1) separately, wherein, when the temperature range is -130°C to 40°C, each slice is measured once at an interval of 10°C from low temperature to high temperature, and at the same time At one temperature, the frequency range is 10 ^-1 Hz to 10 ⁶ Hz, and each slice is measured once at a decreasing ratio of 1.5 times from high frequency to low frequency; 3) Through the measured data obtained in step 2), the imaginary part of the permittivity ε" of each slice is taken as the ordinate, and the frequency f is taken as the abscissa, and the imaginary part of the permittivity ε" is changed with the frequency f at different temperatures The relaxation activation energy value corresponding to each loss peak is calculated according to the Arrhenius formula, and the defects corresponding to the loss peak are judged by the relaxation activation energy to be oxygen vacancies and zinc interstitial intrinsic defects respectively; 4) Compare the peak-to-peak loss of the dielectric spectrum ε"~f of each slice at -100°C, and obtain the distribution of the two intrinsic defect concentrations of oxygen vacancies and zinc interstitials in the resistor slice in the current direction, that is, the loss The distribution of the peak-to-peak value in the current direction, according to the change rate k of the zinc interstitial defect concentration, is used to judge the aging degree of the zinc oxide arrester resistor. Among them, when 0<k≤20%, the zinc oxide arrester resistor is aging In the initial stage, when 20<k≤100%, the zinc oxide arrester resistor is in the middle aging stage, and when k>100%, the zinc oxide arrester resistor is in the late aging stage. 2. a kind of detection method for the aging degree of zinc oxide surge arrester resistive sheet according to claim 1, it is characterized in that, in step 1), after each section is polished, take distilled water or alcohol as cleaning liquid, use ultrasonic cleaner Wash 6-7 times, 15 minutes each time; dry the slices at 80°C and spray gold electrodes for testing. 3. a kind of detection method for the aging degree of zinc oxide surge arrester resistance sheet according to claim 1, is characterized in that, in step 3), the calculation formula of relaxation activation energy u is as follows: $\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; m</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&pi;\&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; u</span>}}{\mathrm{<span\; class="notranslate">\; k</span>}\mathrm{<span\; class="notranslate">\; T</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$ where f _m is the frequency corresponding to the relaxation loss peak, in Hz; T is the absolute temperature in K; _τ0 is a constant independent of temperature; u is the relaxation activation energy in eV; k is Boltzmann's constant, and its value is 1.381×10 ^-23 J/K.