A: The main problems of zinc oxide surge arresters:
1: The zinc oxide lightning arrester is contaminated by rain, snow, leucorrhea, and dust. The potential difference between the inner zinc oxide valve piece and the outer porcelain sleeve may be generated due to the different potential distribution inside and outside the zinc oxide arrester, resulting in a radial discharge phenomenon. Occurs and damages the entire arrester.
2: The zinc oxide surge arrester is subject to the impact voltage and the valve plate will also age under the action of the impact voltage energy.
3: As the zinc oxide surge arrester cancels the series gap, under the action of the grid operating voltage, the body must flow current, and the active component in the current will cause the zinc oxide valve slice to generate heat, which in turn will cause changes in the volt-ampere characteristics. This is a positive feedback process. The long-term effect will cause the zinc oxide valve to age until thermal breakdown occurs.
4: The internal moisture of the zinc oxide arrester or poor insulation performance of the insulating bracket will increase the power frequency current and increase the power consumption. In severe cases, internal discharge may be caused.
II: Instrument Test Principles and Features 1: The software can be used to find the voltage reference so that the voltage signal does not need to be taken from the PT. (This item can be selected by software)
2: The use of FPGA hardware sampling technology, program-controlled amplification technology, making the sampling rate increased to 200k, you can actually capture the original current and voltage signals. Make the test result stable and reliable. Can effectively filter out high-frequency interference harmonics.
3: On-site testing is very convenient because of the internal lithium-ion battery and data wireless transmission technology.
4: The use of embedded industrial processors, making the speed of operation faster, easy to set up, you can simulate a variety of algorithms, the transparency of the test method increases, the instrument as an analysis tool, truly arbitrary.
5: Three-phase simultaneous test can easily remove interphase interference. (This item can be selected by software)
6: The software has various functions such as device management and database management. The upper computer and the instrument share one software.
7: Measure voltage and current signals, perform fast Fourier transform, and calculate capacitive and resistive components (fundamental and harmonic).
III: Theory and Practice Conclusion 1: The capacitive current at the bottom does not change only when the arrester is uniformly degraded. When uneven degradation occurs, the bottom capacitive current increases. When half of the arresters deteriorate, the capacitive current at the bottom increases most.
2: The fundamental component of the resistive current has a large increase. When the content of harmonics does not increase significantly, it usually appears as serious or damp.
3: Interphase interference affects the test results but does not affect the validity of the test results. Longitudinal comparison using historical data can better reflect the operation of zinc oxide arresters.
4: When the content of resistive current harmonics grows large, and the fundamental component does not increase significantly, it generally shows aging.
IV: Why <br> <br> resistive current test determines whether MOA or moisture aging occurs, the normal operating voltage is typically observed flowing through changes MOA resistive current, i.e., whether the observed increase in resistive leakage current As a basis for judgment. When the zinc oxide arrester is in a suitable charge rate condition, the resistive leakage current only accounts for 10% to 20% of the total current. Therefore, the change of the resistive current of the zinc oxide arrester is only determined by observing the change of the total current. It is difficult. Only by separating the resistive leakage current from the total current can we clearly understand its changes.
1: The zinc oxide lightning arrester is contaminated by rain, snow, leucorrhea, and dust. The potential difference between the inner zinc oxide valve piece and the outer porcelain sleeve may be generated due to the different potential distribution inside and outside the zinc oxide arrester, resulting in a radial discharge phenomenon. Occurs and damages the entire arrester.
2: The zinc oxide surge arrester is subject to the impact voltage and the valve plate will also age under the action of the impact voltage energy.
3: As the zinc oxide surge arrester cancels the series gap, under the action of the grid operating voltage, the body must flow current, and the active component in the current will cause the zinc oxide valve slice to generate heat, which in turn will cause changes in the volt-ampere characteristics. This is a positive feedback process. The long-term effect will cause the zinc oxide valve to age until thermal breakdown occurs.
4: The internal moisture of the zinc oxide arrester or poor insulation performance of the insulating bracket will increase the power frequency current and increase the power consumption. In severe cases, internal discharge may be caused.
II: Instrument Test Principles and Features 1: The software can be used to find the voltage reference so that the voltage signal does not need to be taken from the PT. (This item can be selected by software)
2: The use of FPGA hardware sampling technology, program-controlled amplification technology, making the sampling rate increased to 200k, you can actually capture the original current and voltage signals. Make the test result stable and reliable. Can effectively filter out high-frequency interference harmonics.
3: On-site testing is very convenient because of the internal lithium-ion battery and data wireless transmission technology.
4: The use of embedded industrial processors, making the speed of operation faster, easy to set up, you can simulate a variety of algorithms, the transparency of the test method increases, the instrument as an analysis tool, truly arbitrary.
5: Three-phase simultaneous test can easily remove interphase interference. (This item can be selected by software)
6: The software has various functions such as device management and database management. The upper computer and the instrument share one software.
7: Measure voltage and current signals, perform fast Fourier transform, and calculate capacitive and resistive components (fundamental and harmonic).
III: Theory and Practice Conclusion 1: The capacitive current at the bottom does not change only when the arrester is uniformly degraded. When uneven degradation occurs, the bottom capacitive current increases. When half of the arresters deteriorate, the capacitive current at the bottom increases most.
2: The fundamental component of the resistive current has a large increase. When the content of harmonics does not increase significantly, it usually appears as serious or damp.
3: Interphase interference affects the test results but does not affect the validity of the test results. Longitudinal comparison using historical data can better reflect the operation of zinc oxide arresters.
4: When the content of resistive current harmonics grows large, and the fundamental component does not increase significantly, it generally shows aging.
IV: Why <br> <br> resistive current test determines whether MOA or moisture aging occurs, the normal operating voltage is typically observed flowing through changes MOA resistive current, i.e., whether the observed increase in resistive leakage current As a basis for judgment. When the zinc oxide arrester is in a suitable charge rate condition, the resistive leakage current only accounts for 10% to 20% of the total current. Therefore, the change of the resistive current of the zinc oxide arrester is only determined by observing the change of the total current. It is difficult. Only by separating the resistive leakage current from the total current can we clearly understand its changes.
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