什么是電流表

電(dian)流表是指用來(lai)測(ce)量交、直流電(dian)路(lu)中(zhong)(zhong)電(dian)流的儀表。在(zai)電(dian)路(lu)圖(tu)中(zhong)(zhong)，電(dian)流表的符號為"圈A"。電(dian)流值以“安”或“A"為標準(zhun)單(dan)位。

電流表分類

1、直流電流表：主要采用(yong)磁電(dian)(dian)系(xi)或(huo)電(dian)(dian)動系(xi)測(ce)量(liang)機(ji)構(gou)(gou)(見機(ji)械式指(zhi)示(shi)電(dian)(dian)表測(ce)量(liang)機(ji)構(gou)(gou))，這些測(ce)量(liang)機(ji)構(gou)(gou)的測(ce)量(liang)基本量(liang)是(shi)電(dian)(dian)流，可用(yong)來(lai)直(zhi)接(jie)測(ce)小電(dian)(dian)流。

2、交流電流表：可(ke)(ke)采(cai)用(yong)(yong)電(dian)(dian)(dian)(dian)磁系或電(dian)(dian)(dian)(dian)動系測(ce)量機構(gou)。為(wei)(wei)使磁電(dian)(dian)(dian)(dian)系測(ce)量機構(gou)也能用(yong)(yong)于測(ce)量交流(liu)電(dian)(dian)(dian)(dian)流(liu)，可(ke)(ke)利(li)用(yong)(yong)整流(liu)器(qi)或熱電(dian)(dian)(dian)(dian)偶等器(qi)件先將交流(liu)轉換(huan)為(wei)(wei)直流(liu)；由它們組合而成的電(dian)(dian)(dian)(dian)表(biao)分別稱為(wei)(wei)整流(liu)式電(dian)(dian)(dian)(dian)流(liu)表(biao)(見整流(liu)式電(dian)(dian)(dian)(dian)表(biao))、熱電(dian)(dian)(dian)(dian)式電(dian)(dian)(dian)(dian)流(liu)表(biao)。為(wei)(wei)擴大量程以測(ce)量大電(dian)(dian)(dian)(dian)流(liu)，整流(liu)式電(dian)(dian)(dian)(dian)流(liu)表(biao)也采(cai)用(yong)(yong)分流(liu)器(qi)；電(dian)(dian)(dian)(dian)動系電(dian)(dian)(dian)(dian)流(liu)表(biao)的做法同前；電(dian)(dian)(dian)(dian)磁系電(dian)(dian)(dian)(dian)流(liu)表(biao)則是加粗線(xian)圈導線(xian)、減少匝數。對(dui)于更大的測(ce)量電(dian)(dian)(dian)(dian)流(liu)值需配(pei)合電(dian)(dian)(dian)(dian)流(liu)互感器(qi)使用(yong)(yong)。

電流表怎么使用

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1、接表：電(dian)(dian)流(liu)(liu)表(biao)必須串聯在待測電(dian)(dian)路中(zhong)，使電(dian)(dian)流(liu)(liu)從(cong)電(dian)(dian)流(liu)(liu)表(biao)的“+”接(jie)線柱流(liu)(liu)入，從(cong)“－”接(jie)線柱流(liu)(liu)出。使用電(dian)(dian)流(liu)(liu)表(biao)的時候，它的兩個(ge)接(jie)線柱千萬不(bu)能直(zhi)接(jie)接(jie)到電(dian)(dian)源的兩極上，否則由于電(dian)(dian)流(liu)(liu)過大而將電(dian)(dian)流(liu)(liu)表(biao)燒(shao)壞。

2、選擇表的量程：電(dian)(dian)流表(biao)(biao)(biao)有三個(ge)(ge)(ge)接(jie)線柱(zhu)(zhu)(zhu)(zhu)，如上(shang)圖(tu)所示，若電(dian)(dian)流表(biao)(biao)(biao)接(jie)在“+”和“0.6”兩個(ge)(ge)(ge)接(jie)線柱(zhu)(zhu)(zhu)(zhu)上(shang)，其量程(cheng)(cheng)為0.6A，讀表(biao)(biao)(biao)盤(pan)上(shang)下(xia)面的(de)(de)那(nei)組(zu)數值；若接(jie)在“+”和“3”兩個(ge)(ge)(ge)接(jie)線柱(zhu)(zhu)(zhu)(zhu)上(shang)，其量程(cheng)(cheng)為3A，讀表(biao)(biao)(biao)盤(pan)上(shang)上(shang)面的(de)(de)那(nei)組(zu)數值。在實驗前，如果(guo)不(bu)知(zhi)怎(zen)么(me)接(jie)，可先估計(ji)電(dian)(dian)路(lu)中(zhong)的(de)(de)電(dian)(dian)流值。如果(guo)估計(ji)電(dian)(dian)流小于0.6A，應選擇的(de)(de)量程(cheng)(cheng)，如果(guo)估計(ji)電(dian)(dian)流大(da)于0.6A，但小于3A，就(jiu)應選量程(cheng)(cheng)。若不(bu)能估計(ji)，可采用(yong)(yong)試觸的(de)(de)辦法進(jin)行(xing)（固定一個(ge)(ge)(ge)接(jie)線柱(zhu)(zhu)(zhu)(zhu)，用(yong)(yong)電(dian)(dian)路(lu)的(de)(de)另一個(ge)(ge)(ge)線頭(tou)迅速試觸最大(da)量程(cheng)(cheng)的(de)(de)接(jie)線柱(zhu)(zhu)(zhu)(zhu)），再根據電(dian)(dian)流表(biao)(biao)(biao)指針偏轉的(de)(de)角度(du)選用(yong)(yong)適當的(de)(de)量程(cheng)(cheng)。

3、試接電路：按電路圖接好實(shi)物圖以(yi)后(hou)(hou)，必須進(jin)行試接。試接時仔細觀察電流表指(zhi)針(zhen)偏(pian)轉(zhuan)(zhuan)情(qing)況，如果指(zhi)針(zhen)不偏(pian)轉(zhuan)(zhuan)，說(shuo)明(ming)(ming)是電路某處斷(duan)路；若(ruo)指(zhi)針(zhen)向(xiang)相(xiang)反(fan)方向(xiang)偏(pian)轉(zhuan)(zhuan)，說(shuo)明(ming)(ming)表的(de)(de)正、負接線柱接反(fan)了(le)(le)；若(ruo)指(zhi)針(zhen)偏(pian)轉(zhuan)(zhuan)的(de)(de)角度(du)太大了(le)(le)，說(shuo)明(ming)(ming)量程(cheng)選小了(le)(le)；若(ruo)指(zhi)針(zhen)偏(pian)轉(zhuan)(zhuan)的(de)(de)角度(du)太小了(le)(le)，說(shuo)明(ming)(ming)量程(cheng)太大了(le)(le)。然后(hou)(hou)根據試接時觀察到的(de)(de)情(qing)況，做相(xiang)應的(de)(de)調整后(hou)(hou)再進(jin)行相(xiang)關的(de)(de)實(shi)驗。

電流表怎么讀數

首先弄清表(biao)盤(pan)上每個(ge)(ge)大(da)格(ge)(ge)表(biao)示(shi)(shi)(shi)多(duo)少(shao)(shao)，每個(ge)(ge)小(xiao)(xiao)格(ge)(ge)又表(biao)示(shi)(shi)(shi)多(duo)少(shao)(shao)。如圖所示(shi)(shi)(shi)，每個(ge)(ge)大(da)格(ge)(ge)表(biao)示(shi)(shi)(shi)0.2A，每個(ge)(ge)小(xiao)(xiao)格(ge)(ge)表(biao)示(shi)(shi)(shi)0.02A，此時能準確到0.02A。然后再看指(zhi)針位置，現指(zhi)針所指(zhi)位置是2個(ge)(ge)大(da)格(ge)(ge)零3個(ge)(ge)小(xiao)(xiao)格(ge)(ge)，則(ze)電(dian)流表(biao)的(de)讀(du)數(shu)應是。

電流表維護方法

1、由于磁(ci)電(dian)(dian)系電(dian)(dian)流表的過(guo)載(zai)能力很(hen)小(xiao)，使(shi)用(yong)時一定(ding)要注意連接電(dian)(dian)路的極性和量限的選擇。

2、若(ruo)在測量(liang)中發現指(zhi)針反(fan)向偏(pian)轉或正(zheng)向偏(pian)轉超過標度尺(chi)上滿刻度線，應立即斷(duan)電(dian)停止(zhi)測量(liang)，待連接正(zheng)確(que)或重新選擇更(geng)大(da)量(liang)跟的(de)電(dian)流表后再進行測量(liang)。

3、當(dang)測量工(gong)作完畢(bi)后，應(ying)先斷(duan)電源，再從(cong)測量電路中(zhong)取下電流表，將其放置在干(gan)燥、通風(feng)和(he)陰涼的(de)(de)環(huan)境中(zhong)對靈敏度、準(zhun)確度很高的(de)(de)微(wei)安(an)(an)表和(he)室安(an)(an)表，應(ying)用(yong)導(dao)線將正、負端鈕連接(jie)起來，以保護儀表的(de)(de)測量機構。