大型地網接地電阻測試儀結構與原理

本(ben)儀器主要由提(ti)供測試電(dian)(dian)(dian)(dian)流(liu)(liu)的(de)異頻電(dian)(dian)(dian)(dian)源、電(dian)(dian)(dian)(dian)流(liu)(liu)和(he)電(dian)(dian)(dian)(dian)壓測量(liang)電(dian)(dian)(dian)(dian)路以及(ji)微電(dian)(dian)(dian)(dian)腦測控系統組成。儀器通過測量(liang)接(jie)(jie)地裝置的(de)電(dian)(dian)(dian)(dian)位升高與(yu)流(liu)(liu)入接(jie)(jie)地裝置的(de)電(dian)(dian)(dian)(dian)流(liu)(liu)之(zhi)比來測量(liang)接(jie)(jie)地阻抗。

大型地網接地電阻測試儀結構與原理

異頻恒流電源可輸出頻率為45Hz或55Hz的正弦波測試電流，輸出頻率受微電腦系統控制。其輸出經過隔離后通過儀器面板上的C1、C2兩個端子輸出。電壓放大器為一個高輸入阻抗放大器，它將P1、P2兩端的電壓放大后送給濾波器。電流放大器將從電流互感器取得的電流信號進行放大后送給濾波器。濾波器用于濾除干擾信號，只允許45Hz和55Hz信號通過。A/D轉換器用于將電壓和電流信號轉換為數字信號以便微電腦系統進行分析處理。 大型地網接地電阻測試儀用戶啟(qi)動接(jie)地(di)阻(zu)(zu)(zu)抗(kang)(kang)(kang)測(ce)(ce)量后，儀器首先(xian)開啟(qi)異頻(pin)(pin)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)使之(zhi)輸(shu)出(chu)(chu)頻(pin)(pin)率為(wei)45Hz的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)，待電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)穩定(ding)之(zhi)后，微電(dian)(dian)(dian)(dian)(dian)(dian)(dian)腦系統(tong)通(tong)過(guo)A/D轉(zhuan)換器取得(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓和(he)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)波(bo)形數(shu)據(ju)，進(jin)(jin)行數(shu)字濾波(bo)后計(ji)算(suan)出(chu)(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓V45和(he)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)I45及(ji)其(qi)相位差,再進(jin)(jin)一步計(ji)算(suan)出(chu)(chu)阻(zu)(zu)(zu)抗(kang)(kang)(kang)Z45、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)分量R45和(he)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)抗(kang)(kang)(kang)分量X45。然后，切換異頻(pin)(pin)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)的(de)輸(shu)出(chu)(chu)頻(pin)(pin)率為(wei)55Hz，經過(guo)同(tong)樣的(de)步驟后可計(ji)算(suan)出(chu)(chu)阻(zu)(zu)(zu)抗(kang)(kang)(kang)Z55、電(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)(zu)(zu)分量R55和(he)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)抗(kang)(kang)(kang)分量X55。取Z45 和(he)Z55的(de)平均值作(zuo)為(wei)工頻(pin)(pin)接(jie)地(di)阻(zu)(zu)(zu)抗(kang)(kang)(kang)Z50。后，關閉(bi)異頻(pin)(pin)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)，通(tong)過(guo)液晶屏顯(xian)示(shi)測(ce)(ce)量結(jie)果。因此(ci)阻(zu)(zu)(zu)抗(kang)(kang)(kang)測(ce)(ce)量時(shi)，儀器測(ce)(ce)量的(de)是兩(liang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓輸(shu)入端P1、P2之(zhi)間的(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓與電(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)輸(shu)出(chu)(chu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)之(zhi)比。