【正文】 構(gòu)成。根據(jù)設(shè)計要求、使用環(huán)境、成本等因素，選用MQ2型半導(dǎo)體電阻式氣體傳感器。該傳感器是對以烷類氣體為主的多種氣體有良好敏感特性的廣譜型半導(dǎo)體敏感器件。它的靈敏度適中，具有響應(yīng)與恢復(fù)特性好，長期工作穩(wěn)定性、重現(xiàn)性、不易受環(huán)境影響及抗溫濕度影響等優(yōu)點。在系統(tǒng)單片機(jī)控制電路的設(shè)計上，采用了STC89C52單片機(jī)作為核心芯片，充分利用了其高速數(shù)據(jù)處理能力和豐富的片內(nèi)外設(shè)，實現(xiàn)了儀器的小型化和智能化。使儀器具有結(jié)構(gòu)簡單、性能穩(wěn)定、體積小、成本低等優(yōu)點。由于氣體傳感器需要在加熱狀態(tài)下工作，溫度越高，反應(yīng)越快，響應(yīng)時間和恢復(fù)時間就越快。為提高響應(yīng)時間，保證傳感器準(zhǔn)確地、穩(wěn)定地工作，需要向氣體傳感器持續(xù)供給5V的加熱電壓。本報警器能實現(xiàn)范圍檢測工作，當(dāng)煙霧的濃度達(dá)到設(shè)定的濃度以及溫度達(dá)到設(shè)定值時，發(fā)出聲光報警。在本論文研制的報警器的基礎(chǔ)上，可以再做適當(dāng)?shù)墓δ軘U(kuò)展，使可燃性氣體報警器的功能更加完善，安全性更高，使用更加方便等。 沈陽理工大學(xué)學(xué)士學(xué)位論文致謝通過這一階段的努力，我的畢業(yè)論文《基于單片機(jī)的煙霧報警裝置設(shè)計》終于完成了，這意味著大學(xué)生活即將結(jié)束。在大學(xué)階段，我在學(xué)習(xí)上和思想上都受益非淺，這除了自身的努力外，與各位老師、同學(xué)和朋友的關(guān)心、支持和鼓勵是分不開的。在本論文的寫作過程中，我的導(dǎo)師杜焱，廉哲老師傾注了大量的心血，從選題到開題報告，從寫作提綱，到一遍又一遍地指出每稿中的具體問題，嚴(yán)格把關(guān)，循循善誘，在此我表示衷心感謝。同時我還要感謝在我學(xué)習(xí)期間給我極大關(guān)心和支持的各位老師以及關(guān)心我的同學(xué)和朋友。寫作畢業(yè)論文是一次再系統(tǒng)學(xué)習(xí)的過程，畢業(yè)論文的完成，同樣也意味著新的學(xué)習(xí)生活的開始。我將銘記我曾是一名沈陽理工學(xué)子，在今后的工作中把理工的優(yōu)良傳統(tǒng)發(fā)揚(yáng)光大。參考文獻(xiàn)[1] [M]..[2] 陳愛萍,何智勇,[J].1999(7)[3] [M]..[4] [M]..[5] 樓然苗,[J]..[6] [M]..[7] [M]..[8] [M].[1].[9] [M]..[10]吳丙申,[M]..[11] [M]..附錄ANew HighAccurac0y LowCost Approach for tanδ OnlineMonitoring Based on MCUAbstract Through analyzing the principle of microcurrent sensor and the shortage of zeroflux microcurrent sensor, a new online monitoring method of dielectric tangent of loss angle (tanδ) based on passive microcurrent sensor technology is presented. This method can not only overe difficulties existing in the manufacturing sensors of the high precision relative scale difference and the high precision angular difference which is often necessary in online monitoring of insulation dielectric tanδ, but also can achieve high precision at low cost. This method bines the balance measurement principle and potential puter difference measuring technology, and it can be easily realized by using microcontroller unit (MCU). It also adopts anticircumstance electromagnetic interference and intelligent diagnostic techniques in the course of measurement, so it possesses great antiinterference ability under strong electromagnetic interference environment. Both the principle analysis and the onsite test have proved that this measure method can reach goodtanδ monitoring precision.Index Terms Balance measurement principle, Dielectric loss, High voltage and insulation engineering, Online measurement, Zeroflux, Microcurrent sensor.I. INTRODUCTIONIT will be a great technical advance in power system safelyworking if electric equipment insulation onlinemonitoring could carry into effect, it is worth to researchand develop deeply. There are more than twenty years ofdevelopment of the power equipment online monitoringmeasurement in China. Many universities and institutes arepaying attention to new methods in this field. Now theresearch is focus on technology of signal obtaining andprocessing, and also reducing molestation. The way ofsignal obtaining is to measure current which passed thecapacitance equipment by microcurrent sensor. Microcurrentsensors used in this way always are no energy, their intensityof iron core magnetic inductions is affected by temporal inputcurrent and load characteristic easily. This brings unsteadinessof sensor39。s angle difference and relative scale difference IXitwill bring measurement difference and steadiness. To solvethis question, part of researchers are researching zero fluxcurrent sensor, which is expected to have capability ofmonitoring system. Another part of researchers try tosolve the question of unsteadiness of sensor39。s angle differenceby signal processing technology and data fusion technology. It is also a brainteaser to obtain a steadiness and accuratetanδmeasurement of online monitoring. It is important if anew tanδonline monitoring method could be found to applyon it.Owing to the difficulties existing in the manufacture ofsensor and microcurrent dielectric loss tanδmeasurementmethods have not been resolved until now, which blocks thepopularization of the insulation online monitoring technology. Based on the existing status of insulation online monitoringmicrocurrent sensor and dielectric loss tanδmonitoringmeasuring technique, this paper proposes a low cost highprecision online dielectric loss tanδmonitoring measurementmethod.II. PRINCIPLE OF MICROCURRENT SENSOR AND ANALYSIS OF EXISTING PROBLEMCurrent sensor39。s primary coil and secondary coil cancouple by magnetic energy. Using T model equivalent circuit, the current sensor can be equivalent as Figl:Fig. 1. The equivalent circuit of current sensor. The vector map of current sensorIn , I1 is the measured primary current, Z1 is the primary loop impedance including the leaking reactance and the coil internal resistance, Z2e is the value of converted secondary circuit resistance, Zi, is converted value of the secondary load reactance, Zm is the field resistance, 1o is the field current. The is the vector map of current sensor corresponding to 39。s equivalent circuit. In Bm is the intensity of iron core magnetic induction. Relative scale difference of current sensor f is the relative error of converted secondary current at rated ratio to primary current with the primary practicable current, .:The angular difference of current sensor is obtained by reversing the phase angle of secondary current, then subtracting the primary practicable phase angel. Theoretically the error of current sensor mostly caused by field current lo. From and , it can be seen that because , then , which causes relative scale difference and angular difference. If=0, there is no field current, then current sensor will be in the ideal condition and the phase angle difference between primary current and secondary current is 180α, so angular difference and relative scale difference will not exist. Based on this theory the zero flux microcurrent sensor is designed for insulation online monitoring at the present time. By dynamic tracking field current change and using negative feedback technology, it will automatically pensate the