本文選題：MOV　切入點(diǎn)：結(jié)晶度　出處：《南京信息工程大學(xué)》2016年碩士論文

【摘要】：針對(duì)MOV在10/350 ps波形和8/20 μ s波形沖擊下的破壞的問題,本文使用掃描電鏡(SEM)結(jié)合材料成分分析X射線衍射儀(XRD)研究了氧化鋅壓敏電阻(MOV)在高電壓沖擊過程中伴隨的物質(zhì)變化,從微觀結(jié)構(gòu)及組分角度分析MOV在電涌沖擊下的破壞機(jī)理。研究表明：在8/20μ s波形沖擊破壞后期,MOV中的Sb203對(duì)整體致密性的控制能力明顯下降,內(nèi)部晶粒尺寸有所增加,晶界面之間有擠壓破壞的特征；在10/350μ s波形沖擊破壞過程中,大量的熱量會(huì)造成MOV中Bi2O3的逐漸揮發(fā),從而導(dǎo)致MOV內(nèi)部離子遷移不均勻；8/20 μ s波形沖擊下破裂損壞的MOV內(nèi)部微觀結(jié)構(gòu)并不一定發(fā)生很大的變化,受破壞程度與沖擊次數(shù)有關(guān)；但無論遭受哪種類型的沖擊破壞,MOV的破壞實(shí)質(zhì)是內(nèi)部的微觀物質(zhì)由晶態(tài)逐漸轉(zhuǎn)變成半晶態(tài)過程。針對(duì)MOV在單次8/20μ s波形和同時(shí)序多次脈沖沖擊下的破壞問題,本文基于黑龍江省防雷中心的多脈沖沖擊平臺(tái),采用XRD-Rietveld全譜擬合法和SEM-EDS分析研究了氧化鋅壓敏電阻(MOV)在單脈沖與多脈沖沖擊條件下的破壞機(jī)理,以壓敏電壓(U1mA)和漏電流(Iie)為自變量建立了對(duì)MOV結(jié)晶度的預(yù)測(cè)模型。研究表明：脈沖之間的時(shí)間間隔對(duì)MOV的壽命長(zhǎng)短有很大的影響；在單脈沖的沖擊破壞實(shí)驗(yàn)中Bi203與尖晶石中Bi12ZnO20之間會(huì)相互轉(zhuǎn)化,而在多脈沖的沖擊下各MOV的受損存在差異,有的與單脈沖的破壞類似,有的MOV在大電流沖擊下溫度升高會(huì)引起B(yǎng)i203的揮發(fā),造成MOV穿孔破壞；但在任何沖擊條件下,MOV的破壞實(shí)質(zhì)都是內(nèi)部的各微觀成分由晶態(tài)逐漸變?yōu)榘刖B(tài)過程。針對(duì)MOV多片并聯(lián)在沖擊老化過程中各閥片的配合問題,本文通過沖擊實(shí)驗(yàn),紅外溫槍測(cè)溫,SEM掃描電鏡分析表征等實(shí)驗(yàn)手段研究了MOV多片并聯(lián)在沖擊老化過程中溫度差的變化。研究表明：在長(zhǎng)期電涌沖擊下,并聯(lián)體中各MOV受損情況不盡相同,受損較嚴(yán)重的MOV甚至?xí)霈F(xiàn)穿晶破壞現(xiàn)象,將導(dǎo)致其阻性與其他MOV的阻性產(chǎn)生很大差異,當(dāng)再次經(jīng)受電涌沖擊時(shí)其將會(huì)吸收更多的沖擊電流,這樣就會(huì)造成各MOV的通流量不同,從而產(chǎn)生溫度差。根據(jù)此現(xiàn)象,設(shè)計(jì)了一種嵌入式多點(diǎn)溫度無線監(jiān)控系統(tǒng),該系統(tǒng)能判斷電涌保護(hù)器中各MOV的配合情況以及整體的老化程度,具有針對(duì)性強(qiáng),實(shí)時(shí)高效的特點(diǎn)。
[Abstract]:In order to solve the damage problem of MOV under the shock of 10 / 350 PS and 8 / 20 渭 s waveforms, the material changes of ZnO varistors during high voltage shock were studied by means of scanning electron microscopy (SEM) and material composition analysis (XRD). The failure mechanism of MOV under surge impact is analyzed from the point of view of microstructure and composition. The results show that the control ability of Sb203 in 8 / 20 渭 s wave shock damage is obviously decreased, and the internal grain size is increased. During the impact failure process of 10 / 350 渭 s wave, a large amount of heat will cause the gradual volatilization of Bi2O3 in MOV. As a result, the internal microstructure of MOV which is damaged by 8 / 20 渭 s waveforms of non-uniform ion migration is not necessarily changed greatly, and the degree of damage is related to the number of shocks. However, no matter what type of shock damage the MOV is subjected to, the essence of the damage is the gradual transformation of the internal microscopic matter from crystalline to semi-crystalline state. In view of the failure problem of MOV under a single 8 / 20 渭 s waveform and simultaneous sequential multiple pulses, Based on the multi-pulse impact platform in the lightning protection center of Heilongjiang Province, the failure mechanism of ZnO varistor under single pulse and multi-pulse impact is studied by XRD-Rietveld full-spectrum fitting and SEM-EDS analysis. The prediction model of MOV crystallinity was established using varistor voltage U1mAand leakage current as independent variables. The results show that the time interval between pulses has a great influence on the lifetime of MOV. In the single pulse impact failure experiment, the Bi203 and Bi12ZnO20 in spinel transform each other, but the damage of each MOV is different under the impact of multiple pulses, some of them are similar to the damage of single pulse. Some MOV under the impact of high current temperature will cause Bi203 volatilization, resulting in MOV perforation damage; However, under any impact conditions, the essence of the failure of MOV is the gradual transformation of the microcosmic components from crystalline to semi-crystalline. In view of the problem of the matching of various valves in parallel connection of MOV during impact aging, the impact experiments are carried out in this paper. The change of temperature difference during shock aging of MOV was studied by means of scanning electron microscope (SEM) analysis and characterization of infrared thermometer. The results showed that the damage of MOV in the parallel was different under long term surge shock. The more severely damaged MOV may even have transgranular breakage, which will lead to a great difference between its resistance and that of other MOV. When it is subjected to the surge shock again, it will absorb more shock current, which will result in different flux of each MOV. According to this phenomenon, an embedded multi-point temperature wireless monitoring system is designed. The system can judge the coordination of MOV in surge protector and the aging degree of the whole system. It has the characteristics of strong pertinence and high efficiency in real time.
【學(xué)位授予單位】：南京信息工程大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TM862;P427.3
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本文編號(hào)：1661094