什么是電流表
電(dian)(dian)(dian)流(liu)表是指用來測量交、直流(liu)電(dian)(dian)(dian)路中(zhong)電(dian)(dian)(dian)流(liu)的儀表。在電(dian)(dian)(dian)路圖中(zhong),電(dian)(dian)(dian)流(liu)表的符號為"圈A"。電(dian)(dian)(dian)流(liu)值以“安”或“A"為標準單(dan)位。
電流表分類
1、直流電流表:主要采(cai)用(yong)磁電(dian)系(xi)(xi)或電(dian)動系(xi)(xi)測(ce)量機(ji)構(見機(ji)械(xie)式指(zhi)示電(dian)表測(ce)量機(ji)構),這些測(ce)量機(ji)構的(de)測(ce)量基(ji)本量是電(dian)流,可用(yong)來直接測(ce)小電(dian)流。
2、交流電流表:可采(cai)用(yong)電(dian)(dian)(dian)(dian)(dian)磁(ci)系(xi)(xi)(xi)或電(dian)(dian)(dian)(dian)(dian)動系(xi)(xi)(xi)測量機構(gou)。為(wei)使磁(ci)電(dian)(dian)(dian)(dian)(dian)系(xi)(xi)(xi)測量機構(gou)也能(neng)用(yong)于(yu)測量交流(liu)(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu),可利(li)用(yong)整(zheng)(zheng)(zheng)流(liu)(liu)(liu)(liu)器(qi)或熱(re)電(dian)(dian)(dian)(dian)(dian)偶等器(qi)件先將交流(liu)(liu)(liu)(liu)轉(zhuan)換為(wei)直流(liu)(liu)(liu)(liu);由它們(men)組(zu)合而成的(de)電(dian)(dian)(dian)(dian)(dian)表(biao)分(fen)別稱為(wei)整(zheng)(zheng)(zheng)流(liu)(liu)(liu)(liu)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)表(biao)(見整(zheng)(zheng)(zheng)流(liu)(liu)(liu)(liu)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)表(biao))、熱(re)電(dian)(dian)(dian)(dian)(dian)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)表(biao)。為(wei)擴大量程以(yi)測量大電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu),整(zheng)(zheng)(zheng)流(liu)(liu)(liu)(liu)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)表(biao)也采(cai)用(yong)分(fen)流(liu)(liu)(liu)(liu)器(qi);電(dian)(dian)(dian)(dian)(dian)動系(xi)(xi)(xi)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)表(biao)的(de)做法同前;電(dian)(dian)(dian)(dian)(dian)磁(ci)系(xi)(xi)(xi)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)表(biao)則是加(jia)粗線(xian)圈(quan)導線(xian)、減少匝數。對于(yu)更大的(de)測量電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)值(zhi)需配合電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)互感器(qi)使用(yong)。
電流表怎么使用
1、接表:電流(liu)(liu)(liu)(liu)(liu)表必須串聯在(zai)待(dai)測電路中,使電流(liu)(liu)(liu)(liu)(liu)從電流(liu)(liu)(liu)(liu)(liu)表的(de)(de)“+”接(jie)(jie)線柱流(liu)(liu)(liu)(liu)(liu)入,從“-”接(jie)(jie)線柱流(liu)(liu)(liu)(liu)(liu)出。使用電流(liu)(liu)(liu)(liu)(liu)表的(de)(de)時候,它的(de)(de)兩(liang)個接(jie)(jie)線柱千萬不能直(zhi)接(jie)(jie)接(jie)(jie)到電源的(de)(de)兩(liang)極上,否則由于電流(liu)(liu)(liu)(liu)(liu)過大而將電流(liu)(liu)(liu)(liu)(liu)表燒壞。
2、選擇表的量程:電流(liu)表有(you)三個(ge)接線柱,如上(shang)(shang)圖所示(shi),若(ruo)電流(liu)表接在(zai)“+”和“0.6”兩個(ge)接線柱上(shang)(shang),其量(liang)程(cheng)為0.6A,讀(du)表盤上(shang)(shang)下(xia)面的(de)(de)那組(zu)數(shu)值(zhi)(zhi)(zhi);若(ruo)接在(zai)“+”和“3”兩個(ge)接線柱上(shang)(shang),其量(liang)程(cheng)為3A,讀(du)表盤上(shang)(shang)上(shang)(shang)面的(de)(de)那組(zu)數(shu)值(zhi)(zhi)(zhi)。在(zai)實驗前,如果不知(zhi)怎(zen)么接,可先估(gu)計電路中的(de)(de)電流(liu)值(zhi)(zhi)(zhi)。如果估(gu)計電流(liu)小于(yu)(yu)0.6A,應選(xuan)(xuan)擇(ze)的(de)(de)量(liang)程(cheng),如果估(gu)計電流(liu)大于(yu)(yu)0.6A,但小于(yu)(yu)3A,就應選(xuan)(xuan)量(liang)程(cheng)。若(ruo)不能估(gu)計,可采用試(shi)觸(chu)的(de)(de)辦(ban)法進行(固(gu)定(ding)一個(ge)接線柱,用電路的(de)(de)另(ling)一個(ge)線頭迅速試(shi)觸(chu)最大量(liang)程(cheng)的(de)(de)接線柱),再根據電流(liu)表指(zhi)針偏轉的(de)(de)角度選(xuan)(xuan)用適當(dang)的(de)(de)量(liang)程(cheng)。
3、試接電路:按(an)電(dian)路(lu)圖(tu)接(jie)好(hao)實物圖(tu)以后,必須進(jin)行(xing)(xing)試接(jie)。試接(jie)時仔(zi)細觀(guan)察(cha)電(dian)流表指針(zhen)偏轉(zhuan)(zhuan)(zhuan)情況,如果指針(zhen)不偏轉(zhuan)(zhuan)(zhuan),說(shuo)明(ming)是電(dian)路(lu)某處(chu)斷(duan)路(lu);若(ruo)(ruo)指針(zhen)向(xiang)(xiang)相反(fan)方向(xiang)(xiang)偏轉(zhuan)(zhuan)(zhuan),說(shuo)明(ming)表的(de)(de)正、負接(jie)線柱接(jie)反(fan)了(le);若(ruo)(ruo)指針(zhen)偏轉(zhuan)(zhuan)(zhuan)的(de)(de)角度太大了(le),說(shuo)明(ming)量程選小了(le);若(ruo)(ruo)指針(zhen)偏轉(zhuan)(zhuan)(zhuan)的(de)(de)角度太小了(le),說(shuo)明(ming)量程太大了(le)。然(ran)后根據試接(jie)時觀(guan)察(cha)到的(de)(de)情況,做(zuo)相應的(de)(de)調整后再進(jin)行(xing)(xing)相關的(de)(de)實驗。
電流表怎么讀數
首先弄清表盤上每個(ge)(ge)大格(ge)表示(shi)多少,每個(ge)(ge)小(xiao)格(ge)又表示(shi)多少。如圖所(suo)示(shi),每個(ge)(ge)大格(ge)表示(shi)0.2A,每個(ge)(ge)小(xiao)格(ge)表示(shi)0.02A,此時能準(zhun)確到0.02A。然(ran)后再(zai)看指針位置,現指針所(suo)指位置是2個(ge)(ge)大格(ge)零3個(ge)(ge)小(xiao)格(ge),則電(dian)流表的讀數應是。
電流表維護方法
1、由(you)于磁(ci)電(dian)系(xi)電(dian)流表(biao)的(de)過載能力很小,使(shi)用時一定要注意連接電(dian)路的(de)極(ji)性和量限的(de)選擇。
2、若在測量(liang)(liang)中發(fa)現指針反(fan)向偏(pian)轉或(huo)正(zheng)向偏(pian)轉超過標度(du)尺上滿刻度(du)線,應立即斷電(dian)停止測量(liang)(liang),待連接正(zheng)確或(huo)重新選擇更大量(liang)(liang)跟的電(dian)流(liu)表(biao)后再進行測量(liang)(liang)。
3、當測(ce)量工作完(wan)畢后,應先斷(duan)電(dian)源(yuan),再從測(ce)量電(dian)路中(zhong)取(qu)下電(dian)流表(biao),將其放置在干(gan)燥、通風和陰涼的環境中(zhong)對靈敏度、準確(que)度很高的微(wei)安表(biao)和室安表(biao),應用(yong)導線將正、負端鈕連接起來,以保護儀(yi)表(biao)的測(ce)量機構。