兆(zhao)歐(ou)表的刻度(du)是以兆(zhao)歐(ou)(MΩ)為單位的。兆(zhao)歐(ou)表由中大規模集成(cheng)電路組成(cheng)。本表輸出功(gong)率大,短路電流值高(gao),輸出電壓等(deng)級(ji)多(duo)(每種機型有四個(ge)電壓等(deng)級(ji))。
兆(zhao)歐表是電(dian)力(li)、郵電(dian)、通信、機(ji)電(dian)安裝和(he)維修以(yi)及利用電(dian)力(li)作為工(gong)業(ye)動力(li)或(huo)能源的工(gong)業(ye)企(qi)業(ye)部門(men)常(chang)用而必不可少的儀表。它適用于測量各(ge)種絕(jue)緣(yuan)材料的電(dian)阻值及變壓器(qi)、電(dian)機(ji)、電(dian)纜(lan)及電(dian)器(qi)設(she)備等的絕(jue)緣(yuan)電(dian)阻。
數(shu)(shu)字(zi)兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)、指(zhi)針兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)、絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)表(biao)(biao)、高(gao)(gao)壓(ya)(ya)(ya)(ya)絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)試(shi)(shi)(shi)儀、絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)量(liang)儀、絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)特性測(ce)試(shi)(shi)(shi)儀、電(dian)(dian)(dian)(dian)動(dong)搖表(biao)(biao)、電(dian)(dian)(dian)(dian)子式(shi)(shi)(shi)絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)試(shi)(shi)(shi)儀、大功率(lv)高(gao)(gao)壓(ya)(ya)(ya)(ya)兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)、兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)、數(shu)(shu)字(zi)式(shi)(shi)(shi)兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)、數(shu)(shu)顯兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)、絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)試(shi)(shi)(shi)儀、高(gao)(gao)壓(ya)(ya)(ya)(ya)絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)試(shi)(shi)(shi)儀、絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)量(liang)儀、絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)特性測(ce)試(shi)(shi)(shi)儀、電(dian)(dian)(dian)(dian)動(dong)搖表(biao)(biao)、數(shu)(shu)字(zi)搖表(biao)(biao)、數(shu)(shu)顯搖表(biao)(biao)、數(shu)(shu)字(zi)兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)計、高(gao)(gao)壓(ya)(ya)(ya)(ya)數(shu)(shu)字(zi)絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)試(shi)(shi)(shi)儀、數(shu)(shu)字(zi)高(gao)(gao)壓(ya)(ya)(ya)(ya)絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)試(shi)(shi)(shi)儀、數(shu)(shu)字(zi)高(gao)(gao)壓(ya)(ya)(ya)(ya)兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)、數(shu)(shu)字(zi)式(shi)(shi)(shi)高(gao)(gao)壓(ya)(ya)(ya)(ya)兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)、高(gao)(gao)壓(ya)(ya)(ya)(ya)數(shu)(shu)字(zi)式(shi)(shi)(shi)兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)、數(shu)(shu)字(zi)絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)表(biao)(biao)、數(shu)(shu)顯絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)表(biao)(biao)、電(dian)(dian)(dian)(dian)子式(shi)(shi)(shi)絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)試(shi)(shi)(shi)儀、數(shu)(shu)字(zi)式(shi)(shi)(shi)絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)試(shi)(shi)(shi)儀、數(shu)(shu)顯式(shi)(shi)(shi)絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)試(shi)(shi)(shi)儀、數(shu)(shu)顯絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)測(ce)試(shi)(shi)(shi)儀、絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)儀、數(shu)(shu)字(zi)兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)絕(jue)緣(yuan)(yuan)(yuan)(yuan)(yuan)電(dian)(dian)(dian)(dian)阻(zu)儀、數(shu)(shu)字(zi)式(shi)(shi)(shi)電(dian)(dian)(dian)(dian)動(dong)兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)、數(shu)(shu)字(zi)式(shi)(shi)(shi)高(gao)(gao)壓(ya)(ya)(ya)(ya)兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)、大功率(lv)高(gao)(gao)壓(ya)(ya)(ya)(ya)兆(zhao)(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)表(biao)(biao)。
數(shu)字兆歐(ou)表由中(zhong)大(da)(da)規模(mo)集成(cheng)(cheng)電(dian)(dian)(dian)路(lu)組成(cheng)(cheng)。本(ben)表輸出功率大(da)(da),短(duan)路(lu)電(dian)(dian)(dian)流(liu)值高,輸出電(dian)(dian)(dian)壓(ya)(ya)等(deng)級多(有四(si)個(ge)電(dian)(dian)(dian)壓(ya)(ya)等(deng)級)。工(gong)作原(yuan)理(li)為由機內電(dian)(dian)(dian)池作為電(dian)(dian)(dian)源(yuan)經(jing)DC/DC變換產生的(de)直流(liu)高壓(ya)(ya)由E極(ji)(ji)出經(jing)被(bei)測試品到達L極(ji)(ji),從而產生一個(ge)從E到L極(ji)(ji)的(de)電(dian)(dian)(dian)流(liu),經(jing)過(guo)I/V變換經(jing)除法器完成(cheng)(cheng)運(yun)算直接(jie)將被(bei)測的(de)絕緣電(dian)(dian)(dian)阻(zu)值由LCD顯示出來。
1.輸出功(gong)率大、帶載能(neng)力強,抗干擾能(neng)力強。
2.本表外(wai)殼由高強度鋁合金(jin)組成,機內設(she)有等電位保護環和四階(jie)有源低通(tong)濾(lv)波(bo)器,對外(wai)界工頻及強電磁場可(ke)起到(dao)有效的(de)屏蔽作用(yong)(yong)。對容性試(shi)品測(ce)量由于(yu)輸出短路電流大于(yu)1.6mA,很容易使測(ce)試(shi)電壓(ya)迅速(su)上升(sheng)到(dao)輸出電壓(ya)的(de)額定值。對于(yu)低阻值測(ce)量由于(yu)采用(yong)(yong)比例法設(she)計故電壓(ya)下落并不影響測(ce)試(shi)精度。
3.不需人力作(zuo)功,由(you)電(dian)池供電(dian),量(liang)程(cheng)可自動轉(zhuan)換。一目了然的面板(ban)操(cao)作(zuo)和(he)LCD顯示使(shi)得測量(liang)十分方便和(he)迅(xun)捷。
4.本表輸出短(duan)路(lu)電流(liu)可直接測(ce)量,不需帶(dai)載測(ce)量進行估算。
合成電(dian)阻(zu)的(de)方法由于受到設(she)計成本和尺(chi)寸規格的(de)限制被排除在外(wai)。采用的(de)是(shi)分立式高(gao)壓電(dian)阻(zu)器(qi)矩(ju)陣(zhen)的(de)方法,組(zu)成一個陣(zhen)列,能(neng)夠提(ti)(ti)供(gong)500,000多種(zhong)電(dian)阻(zu)值輸(shu)出(chu)。在這種(zhong)校準器(qi)中,有8個范圍的(de)電(dian)阻(zu)值,覆(fu)蓋了10kΩ到10GΩ的(de)范圍,每個范圍均(jun)能(neng)提(ti)(ti)供(gong)4.5位的(de)穩定輸(shu)出(chu)。
收集合適的(de)高壓電(dian)阻器并將其(qi)集成到一(yi)個儀器內又存在另(ling)一(yi)項挑戰。這就是與歐(ou)盟CE認證的(de)一(yi)項強制性要求《低電(dian)壓指令》相(xiang)關的(de)安(an)(an)全性標準(zhun)(zhun)挑戰。與儀器制造商相(xiang)關的(de)標準(zhun)(zhun)是EN61010-測量、控制和實驗室用電(dian)氣設(she)備(bei)的(de)安(an)(an)全要求。
低電(dian)壓指令要求將校準(zhun)器電(dian)壓限制(zhi)為1,000Vrms。那么如何校準(zhun)測試(shi)電(dian)壓高達5kV的(de)兆歐表呢?這(zhe)類(lei)儀器具(ju)有更寬(kuan)的(de)動態范(fan)圍(wei),可測量高到10TΩ的(de)電(dian)阻(zu),并且(qie)提供了(le)如上所(suo)述的(de)保(bao)護端子(zi),使(shi)其(qi)能夠(gou)(gou)準(zhun)確測量非(fei)常(chang)高的(de)電(dian)阻(zu)值。幸(xing)運的(de)是(shi),這(zhe)樣的(de)保(bao)護配(pei)置(zhi)可以使(shi)其(qi)本身形(xing)成一個(ge)電(dian)阻(zu)倍增(zeng)器,能夠(gou)(gou)有效地將一個(ge)已知(zhi)電(dian)阻(zu)倍增(zeng)為1000 倍,如圖(tu)2的(de)例子(zi)所(suo)示。同樣重(zhong)要的(de)是(shi),由于倍增(zeng)器是(shi)一個(ge)分立、隔離、獨立的(de)設備,可以滿(man)足(zu)倍增(zeng)器所(suo)需的(de)高電(dian)壓,它已經不是(shi)《低電(dian)壓指令》所(suo)管轄的(de)范(fan)圍(wei)。
規定(ding)(ding)兆(zhao)(zhao)(zhao)歐表(biao)(biao)(biao)的(de)(de)(de)(de)電(dian)壓(ya)等級應高于被(bei)測物的(de)(de)(de)(de)絕緣電(dian)壓(ya)等級。所以(yi)測量額定(ding)(ding)電(dian)壓(ya)在500V以(yi)下的(de)(de)(de)(de)設備或線(xian)路的(de)(de)(de)(de)絕緣電(dian)阻(zu)時(shi),可選(xuan)(xuan)(xuan)用500V或1000V兆(zhao)(zhao)(zhao)歐表(biao)(biao)(biao);測量額定(ding)(ding)電(dian)壓(ya)在500V以(yi)上(shang)的(de)(de)(de)(de)設備或線(xian)路的(de)(de)(de)(de)絕緣電(dian)阻(zu)時(shi),應選(xuan)(xuan)(xuan)用1000~2500V兆(zhao)(zhao)(zhao)歐表(biao)(biao)(biao);測量絕緣子時(shi),應選(xuan)(xuan)(xuan)用2500~5000V兆(zhao)(zhao)(zhao)歐表(biao)(biao)(biao)。一般(ban)情況(kuang)下,測量低壓(ya)電(dian)氣設備絕緣電(dian)阻(zu)時(shi)可選(xuan)(xuan)(xuan)用0~200MΩ量程(cheng)的(de)(de)(de)(de)兆(zhao)(zhao)(zhao)歐表(biao)(biao)(biao)。
1.測量前(qian)必須將被測設(she)備電源(yuan)切斷,并對地短路(lu)放電。決不能(neng)讓設(she)備帶電進(jin)行(xing)測量,以(yi)保證(zheng)人(ren)身(shen)和設(she)備的(de)(de)安全。對可(ke)能(neng)感應(ying)出高壓電的(de)(de)設(she)備,必須消除這種可(ke)能(neng)性后(hou),才能(neng)進(jin)行(xing)測量。
2.被測(ce)物(wu)表面要清潔.減少接觸電阻,確保(bao)測(ce)量結果的正確性。
3.測量前應將兆(zhao)歐(ou)表(biao)進行(xing)一次開路和(he)短路試驗,檢查(cha)兆(zhao)歐(ou)表(biao)是否(fou)良好。即在兆(zhao)歐(ou)表(biao)未接上被測物之(zhi)前.搖(yao)動手柄使發(fa)電機達到額定轉(zhuan)速(120r/min),觀(guan)察指(zhi)針是否(fou)指(zhi)在標尺(chi)的“∞”位置。將接線柱“線(L)和(he)地(di)(E)”短接,緩(huan)慢搖(yao)動手柄,觀(guan)察指(zhi)針是否(fou)指(zhi)在標尺(chi)的“0”位。如指(zhi)針不能指(zhi)到該指(zhi)的位置,表(biao)明(ming)兆(zhao)歐(ou)表(biao)有故障.應檢修后再用。
4.兆歐表使用時應放在平穩、牢固(gu)的地方,且(qie)遠離大的外(wai)電流導(dao)體(ti)和外(wai)磁(ci)場。
5.必須正確接線。兆歐表上一(yi)(yi)般(ban)有三個接線柱,其中L接在(zai)被(bei)測(ce)物(wu)和大地絕(jue)緣(yuan)的(de)(de)導體部分(fen),E接被(bei)測(ce)物(wu)的(de)(de)外(wai)殼(ke)或(huo)大地。G接在(zai)被(bei)測(ce)物(wu)的(de)(de)屏(ping)蔽(bi)上或(huo)不需要測(ce)量的(de)(de)部分(fen)。測(ce)量絕(jue)緣(yuan)電阻時,一(yi)(yi)般(ban)只用“L”和“E”端(duan)(duan).但在(zai)測(ce)量電纜對(dui)地的(de)(de)絕(jue)緣(yuan)電阻或(huo)被(bei)測(ce)設備的(de)(de)漏電流較嚴重(zhong)時,就(jiu)要使(shi)用“G”端(duan)(duan),并(bing)將(jiang)“G”端(duan)(duan)接屏(ping)蔽(bi)層(ceng)或(huo)外(wai)殼(ke)。線路接好后,可按順時針方向(xiang)轉(zhuan)動搖把.搖動的(de)(de)速(su)(su)度應由慢而快,當轉(zhuan)速(su)(su)達(da)到每分(fen)鐘(zhong)120轉(zhuan)左(zuo)右時(ZC-25型),保(bao)持勻(yun)速(su)(su)轉(zhuan)動,1分(fen)鐘(zhong)后讀數(shu),并(bing)且要邊搖邊讀數(shu),不能停下(xia)來(lai)讀數(shu)。
6.搖(yao)測(ce)時將兆歐表置于水平位置,搖(yao)把轉動時其(qi)端鈕間不(bu)(bu)許短路。搖(yao)動手柄應由慢(man)漸快,若發(fa)現指針指零說明被測(ce)絕緣物可能發(fa)生(sheng)了短路,這時就(jiu)不(bu)(bu)能繼續搖(yao)動手柄.以(yi)防表內線圈發(fa)熱損壞(huai)。
7.讀數完畢(bi).將被測(ce)(ce)設備(bei)放(fang)(fang)電。放(fang)(fang)電方法是將測(ce)(ce)量時(shi)使用的地線從兆歐表(biao)上取下來與被測(ce)(ce)設備(bei)短接一(yi)下即可(ke)(不是兆歐表(biao)放(fang)(fang)電)。
測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)前(qian)(qian)要(yao)先切斷(duan)被(bei)(bei)(bei)測(ce)(ce)(ce)(ce)(ce)設(she)(she)(she)(she)備(bei)的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源,并將(jiang)設(she)(she)(she)(she)備(bei)的(de)(de)(de)(de)(de)(de)(de)導電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)部(bu)分(fen)(fen)與(yu)(yu)(yu)大(da)地接(jie)(jie)(jie)(jie)通,進(jin)行(xing)(xing)充分(fen)(fen)放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian),以保(bao)證安全。用(yong)(yong)數(shu)(shu)字(zi)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)過(guo)的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)氣設(she)(she)(she)(she)備(bei),也要(yao)及(ji)(ji)(ji)時(shi)接(jie)(jie)(jie)(jie)地放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian),方(fang)可進(jin)行(xing)(xing)再(zai)次(ci)測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)。測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)前(qian)(qian)要(yao)先檢查數(shu)(shu)字(zi)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)是否(fou)完好,即(ji)在(zai)(zai)(zai)數(shu)(shu)字(zi)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)未接(jie)(jie)(jie)(jie)上(shang)(shang)被(bei)(bei)(bei)測(ce)(ce)(ce)(ce)(ce)物(wu)之前(qian)(qian),打開(kai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源開(kai)關(guan),檢測(ce)(ce)(ce)(ce)(ce)數(shu)(shu)字(zi)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池情(qing)況(kuang),如果(guo)數(shu)(shu)字(zi)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池欠壓應(ying)(ying)(ying)及(ji)(ji)(ji)時(shi)更(geng)換電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)池,否(fou)則測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)數(shu)(shu)據(ju)不(bu)(bu)(bu)(bu)(bu)可取。將(jiang)測(ce)(ce)(ce)(ce)(ce)試(shi)(shi)(shi)(shi)線(xian)(xian)(xian)(xian)插入接(jie)(jie)(jie)(jie)線(xian)(xian)(xian)(xian)柱“線(xian)(xian)(xian)(xian)(L)和(he)(he)地(E)”,選擇測(ce)(ce)(ce)(ce)(ce)試(shi)(shi)(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓,斷(duan)開(kai)測(ce)(ce)(ce)(ce)(ce)試(shi)(shi)(shi)(shi)線(xian)(xian)(xian)(xian),按下測(ce)(ce)(ce)(ce)(ce)試(shi)(shi)(shi)(shi)按鍵(jian),觀察顯(xian)示(shi)(shi)是否(fou)數(shu)(shu)字(zi)是否(fou)顯(xian)示(shi)(shi)無窮大(da)。將(jiang)接(jie)(jie)(jie)(jie)線(xian)(xian)(xian)(xian)柱“線(xian)(xian)(xian)(xian)(L)和(he)(he)地(E)”短接(jie)(jie)(jie)(jie),按下測(ce)(ce)(ce)(ce)(ce)試(shi)(shi)(shi)(shi)按鍵(jian),觀察是否(fou)顯(xian)示(shi)(shi)“0”。如液晶(jing)屏(ping)不(bu)(bu)(bu)(bu)(bu)顯(xian)示(shi)(shi)“0”,表(biao)(biao)(biao)(biao)明數(shu)(shu)字(zi)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)有(you)故障,應(ying)(ying)(ying)檢修后(hou)(hou)再(zai)用(yong)(yong)。必(bi)須正確接(jie)(jie)(jie)(jie)線(xian)(xian)(xian)(xian)。數(shu)(shu)字(zi)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)上(shang)(shang)一般(ban)有(you)三個接(jie)(jie)(jie)(jie)線(xian)(xian)(xian)(xian)柱,分(fen)(fen)別標有(you)L(線(xian)(xian)(xian)(xian)路)、E(接(jie)(jie)(jie)(jie)地)和(he)(he)G(屏(ping)蔽(bi)(bi)(bi))。其中(zhong)L接(jie)(jie)(jie)(jie)在(zai)(zai)(zai)被(bei)(bei)(bei)測(ce)(ce)(ce)(ce)(ce)物(wu)和(he)(he)大(da)地絕(jue)(jue)緣的(de)(de)(de)(de)(de)(de)(de)導體部(bu)分(fen)(fen),E接(jie)(jie)(jie)(jie)被(bei)(bei)(bei)測(ce)(ce)(ce)(ce)(ce)物(wu)的(de)(de)(de)(de)(de)(de)(de)外殼(ke)或(huo)大(da)地,G接(jie)(jie)(jie)(jie)在(zai)(zai)(zai)被(bei)(bei)(bei)測(ce)(ce)(ce)(ce)(ce)物(wu)的(de)(de)(de)(de)(de)(de)(de)屏(ping)蔽(bi)(bi)(bi)上(shang)(shang)或(huo)不(bu)(bu)(bu)(bu)(bu)需要(yao)測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)的(de)(de)(de)(de)(de)(de)(de)部(bu)分(fen)(fen)。接(jie)(jie)(jie)(jie)線(xian)(xian)(xian)(xian)柱G是用(yong)(yong)來屏(ping)蔽(bi)(bi)(bi)表(biao)(biao)(biao)(biao)面(mian)(mian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)(de)(de)(de)(de)。如測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜的(de)(de)(de)(de)(de)(de)(de)絕(jue)(jue)緣電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)時(shi),由于絕(jue)(jue)緣材料表(biao)(biao)(biao)(biao)面(mian)(mian)存在(zai)(zai)(zai)漏(lou)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu),將(jiang)使測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)結果(guo)不(bu)(bu)(bu)(bu)(bu)準(zhun),尤其是在(zai)(zai)(zai)濕度(du)很大(da)的(de)(de)(de)(de)(de)(de)(de)場合及(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜絕(jue)(jue)緣表(biao)(biao)(biao)(biao)面(mian)(mian)又不(bu)(bu)(bu)(bu)(bu)干(gan)凈(jing)(jing)的(de)(de)(de)(de)(de)(de)(de)情(qing)況(kuang)下,會使測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)誤差很大(da)。為避免(mian)表(biao)(biao)(biao)(biao)面(mian)(mian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)(de)(de)(de)(de)影(ying)響,在(zai)(zai)(zai)被(bei)(bei)(bei)測(ce)(ce)(ce)(ce)(ce)物(wu)的(de)(de)(de)(de)(de)(de)(de)表(biao)(biao)(biao)(biao)面(mian)(mian)加(jia)一個金屬屏(ping)蔽(bi)(bi)(bi)環,與(yu)(yu)(yu)數(shu)(shu)字(zi)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)的(de)(de)(de)(de)(de)(de)(de)“屏(ping)蔽(bi)(bi)(bi)”接(jie)(jie)(jie)(jie)線(xian)(xian)(xian)(xian)柱相連。這樣,表(biao)(biao)(biao)(biao)面(mian)(mian)漏(lou)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)IB從(cong)發電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機正極出發,經(jing)接(jie)(jie)(jie)(jie)線(xian)(xian)(xian)(xian)柱G流(liu)回發電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機負極而(er)構成回路。IB不(bu)(bu)(bu)(bu)(bu)再(zai)經(jing)過(guo)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)的(de)(de)(de)(de)(de)(de)(de)測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)機構,因(yin)(yin)此從(cong)根本上(shang)(shang)消除了表(biao)(biao)(biao)(biao)面(mian)(mian)漏(lou)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)(de)(de)(de)(de)影(ying)響。接(jie)(jie)(jie)(jie)線(xian)(xian)(xian)(xian)柱與(yu)(yu)(yu)被(bei)(bei)(bei)測(ce)(ce)(ce)(ce)(ce)設(she)(she)(she)(she)備(bei)間連接(jie)(jie)(jie)(jie)的(de)(de)(de)(de)(de)(de)(de)導線(xian)(xian)(xian)(xian)不(bu)(bu)(bu)(bu)(bu)能用(yong)(yong)雙(shuang)股(gu)絕(jue)(jue)緣線(xian)(xian)(xian)(xian)或(huo)絞線(xian)(xian)(xian)(xian),應(ying)(ying)(ying)該用(yong)(yong)單(dan)股(gu)線(xian)(xian)(xian)(xian)分(fen)(fen)開(kai)單(dan)獨連接(jie)(jie)(jie)(jie),避免(mian)因(yin)(yin)絞線(xian)(xian)(xian)(xian)絕(jue)(jue)緣不(bu)(bu)(bu)(bu)(bu)良而(er)引起誤差。為獲得正確的(de)(de)(de)(de)(de)(de)(de)測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)結果(guo),被(bei)(bei)(bei)測(ce)(ce)(ce)(ce)(ce)設(she)(she)(she)(she)備(bei)的(de)(de)(de)(de)(de)(de)(de)表(biao)(biao)(biao)(biao)面(mian)(mian)應(ying)(ying)(ying)用(yong)(yong)干(gan)凈(jing)(jing)的(de)(de)(de)(de)(de)(de)(de)布或(huo)棉紗擦試(shi)(shi)(shi)(shi)干(gan)凈(jing)(jing)。測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)具有(you)大(da)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)設(she)(she)(she)(she)備(bei)的(de)(de)(de)(de)(de)(de)(de)絕(jue)(jue)緣電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu),讀(du)(du)數(shu)(shu)后(hou)(hou)不(bu)(bu)(bu)(bu)(bu)能立(li)即(ji)斷(duan)開(kai)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao),否(fou)則已(yi)被(bei)(bei)(bei)充電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)器將(jiang)對(dui)(dui)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian),有(you)可能燒壞(huai)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)。應(ying)(ying)(ying)在(zai)(zai)(zai)讀(du)(du)數(shu)(shu)后(hou)(hou)應(ying)(ying)(ying)首(shou)先斷(duan)開(kai)測(ce)(ce)(ce)(ce)(ce)試(shi)(shi)(shi)(shi)線(xian)(xian)(xian)(xian),然后(hou)(hou)再(zai)停止測(ce)(ce)(ce)(ce)(ce)試(shi)(shi)(shi)(shi),在(zai)(zai)(zai)兆(zhao)(zhao)(zhao)歐(ou)(ou)(ou)(ou)(ou)表(biao)(biao)(biao)(biao)和(he)(he)被(bei)(bei)(bei)測(ce)(ce)(ce)(ce)(ce)物(wu)充分(fen)(fen)放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)以前(qian)(qian),不(bu)(bu)(bu)(bu)(bu)能用(yong)(yong)手觸(chu)及(ji)(ji)(ji)被(bei)(bei)(bei)試(shi)(shi)(shi)(shi)設(she)(she)(she)(she)備(bei)的(de)(de)(de)(de)(de)(de)(de)導電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)部(bu)分(fen)(fen)。測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)設(she)(she)(she)(she)備(bei)的(de)(de)(de)(de)(de)(de)(de)絕(jue)(jue)緣電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)時(shi),還應(ying)(ying)(ying)記下測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)時(shi)的(de)(de)(de)(de)(de)(de)(de)溫度(du)、濕度(du)、被(bei)(bei)(bei)試(shi)(shi)(shi)(shi)物(wu)的(de)(de)(de)(de)(de)(de)(de)有(you)關(guan)狀況(kuang)等,以便(bian)于對(dui)(dui)測(ce)(ce)(ce)(ce)(ce)量(liang)(liang)(liang)(liang)(liang)結果(guo)進(jin)行(xing)(xing)分(fen)(fen)析(xi)。
1.禁止在(zai)雷電(dian)(dian)時(shi)或高(gao)壓設備(bei)附(fu)近測(ce)絕緣電(dian)(dian)阻,只能在(zai)設備(bei)不(bu)帶電(dian)(dian),也沒有感應(ying)電(dian)(dian)的(de)情況下測(ce)量。
2.搖測(ce)過程中(zhong),被測(ce)設(she)備上(shang)不能有(you)人工作。
3.兆歐表(biao)線不(bu)能絞在一起,要(yao)分(fen)開。
4.兆歐表未(wei)(wei)停止(zhi)轉動之前或被測(ce)設備未(wei)(wei)放電之前.嚴禁用手觸(chu)及。拆線(xian)時,也不要觸(chu)及引線(xian)的金(jin)屬部分。
5.測(ce)量(liang)結束時.對(dui)于(yu)大電容設(she)備要放電。
6.兆(zhao)歐表接線(xian)柱(zhu)引出的測量(liang)軟線(xian)絕緣(yuan)應良好(hao),兩根導線(xian)之(zhi)間和導線(xian)與(yu)地(di)之(zhi)間應保持適(shi)當距離,以免影響測量(liang)精度(du)。
7.為(wei)了防止被測設備(bei)表(biao)面泄漏(lou)電(dian)阻(zu),使用兆歐表(biao)時.應(ying)將被測設備(bei)的中間層(如電(dian)纜殼芯之(zhi)間的內層絕緣物)接于保(bao)護環(huan)。
8.要定期校(xiao)驗(yan)其準(zhun)確度。
1、范(fan)圍(wei)為103到1012具有(you)精(jing)度1%的(de)阻抗電橋(qiao)。高(gao)(gao)精(jing)度相對濕度表(RelativeHumidityHygrometer)高(gao)(gao)精(jing)度溫度表(HighaccuracyThermometer)。
2、打開表(biao)蓋,小心切莫損傷電路板上兩條連接電源開關的導線。
3、找到電路板右下(xia)方三(san)個校正(zheng)調節(jie)器(CalibrationPots)。
4、使表在這一環境(jing)條件下起碼1/2小時,取(qu)得自平衡后才(cai)可開始測(ce)試。
5、采用ACL-800表自帶的連接線一(yi)端(duan)連接上鱷魚夾(jia),另(ling)一(yi)端(duan)香蕉插(cha)頭。
6、將3.5毫米長的(de)插(cha)頭插(cha)入表的(de)插(cha)口。
7、用鱷魚夾連接電阻器兩端。
8、三個(ge)校正(zheng)調(diao)節器,最上(shang)面的(de)為(wei)(wei)“濕度”測(ce)量,中間(jian)的(de)為(wei)(wei)“阻(zu)抗”,最下面的(de)為(wei)(wei)“溫度用(yong)小號螺(luo)絲刀(dao)調(diao)節”。順時(shi)針方向(xiang)為(wei)(wei)增加值(zhi)調(diao)節,逆時(shi)針方向(xiang)為(wei)(wei)降低值(zhi)調(diao)節。
9、按下電源開(kai)關,同時比較“溫度”,“濕(shi)度”和“電阻”值。
10、釋放(fang)電源開關(guan),并慢慢調節(jie)相應的校正調節(jie)器。
11、再次按(an)下電源開關,觀察LCD顯示屏。
12、如需要(yao)再校準,可(ke)再按下電(dian)源開關(guan)和調(diao)節校正器(qi)。
13、蓋(gai)上(shang)(shang)表蓋(gai)并(bing)將四個固定螺(luo)絲上(shang)(shang)緊。
14、按下電源開關(guan)確(que)定表是否(fou)工(gong)作正常。
這個測(ce)量方法(fa)是用于測(ce)量物(wu)體表(biao)(biao)(biao)面(mian)一點與表(biao)(biao)(biao)面(mian)上另一接地點之間的(de)表(biao)(biao)(biao)面(mian)電阻,測(ce)量方法(fa)符合EOS/ESDS4.1測(ce)量標準。
A、將(jiang)兩(liang)條(tiao)連線的一端分別(bie)插入表的兩(liang)個3.5毫米(mi)插孔,然后將(jiang)其(qi)中一條(tiao)接(jie)鱷魚夾(jia),另外一條(tiao)與一個5磅重盤(pan)形探頭相(xiang)聯。
B、將鱷(e)魚夾子(zi)接到所(suo)知的接地點上,按照測(ce)量(liang)要(yao)求(qiu)將盤形探頭放(fang)在待(dai)測(ce)物體表面(mian)上。
C、按(an)下測(ce)量(liang)按(an)鈕(niu)直(zhi)至電(dian)阻(單位為歐姆)、相對(dui)濕度、溫度值顯(xian)(xian)示在顯(xian)(xian)示屏上(shang),測(ce)量(liang)結果符合EIA,EOS/ESD,ANSI,IEC-93,CECC,ASTM測(ce)量(liang)標準,對(dui)于(yu)高阻抗材料(liao)的測(ce)量(liang)時為保(bao)證(zheng)測(ce)得高精度測(ce)量(liang)結果,需注意不要使兩引線(xian)(xian)交(jiao)疊,不要用手接觸探頭,引線(xian)(xian)和被測(ce)物體。