【鉗(qian)形電(dian)流表(biao)】鉗(qian)形電(dian)流表(biao)使用(yong)方法 怎樣正確(que)使用鉗形電流(liu)表
鉗形電流(liu)(liu)表是(shi)由電流(liu)(liu)互感器和電流(liu)(liu)表組合而(er)成(cheng)。電流(liu)(liu)互感器的(de)(de)鐵(tie)心(xin)在捏緊扳手時可(ke)以張開;被測電流(liu)(liu)所通過的(de)(de)導線可(ke)以不必切斷就可(ke)穿過鐵(tie)心(xin)張開的(de)(de)缺口,當放(fang)開扳手后鐵(tie)心(xin)閉(bi)合。
通常用普通電流表測量電流時,需要將電路切斷停機后才能將電流表接入進行測量,這是很麻煩的,有時正常運行的電動機不允許這樣做。此時,使用鉗形電流表就顯得方便多了,可以在不切斷電路的情況下來測量電流,但(dan)只(zhi)限(xian)于在被(bei)測線路電壓不超過(guo)500V的情況下使用。
鉗形電流表使用方法
1、測量前(qian),應先檢查鉗(qian)形鐵心的(de)橡膠絕緣(yuan)是否(fou)完好(hao)無(wu)損。鉗(qian)口應清潔、無(wu)銹,閉合(he)后(hou)無(wu)明顯的(de)縫隙(xi)。
2、測量時(shi),應先(xian)估計(ji)被(bei)測電(dian)流大小,選(xuan)擇適(shi)當量程。若無法估計(ji),可先(xian)選(xuan)較大量程,然(ran)后逐檔(dang)減(jian)少(shao),轉換到合(he)適(shi)的檔(dang)位。轉換量程檔(dang)位時(shi),必須在不(bu)帶電(dian)情況(kuang)下或者在鉗口張開情況(kuang)下進行,以免(mian)損(sun)壞儀表。
3、測量時,被測導線應盡量放在鉗(qian)口(kou)中部,鉗(qian)口(kou)的結(jie)合(he)面(mian)如有(you)雜聲(sheng),應重(zhong)新開(kai)合(he)一(yi)次(ci),仍有(you)雜聲(sheng),應處理(li)結(jie)合(he)面(mian),以使(shi)讀數準確。另外,不(bu)可同時鉗(qian)住兩根導線。
4、測(ce)量(liang)5A以(yi)(yi)下(xia)電(dian)流(liu)時,為得到較(jiao)為準確的讀(du)數(shu)(shu),在條件許可時,可將(jiang)導線(xian)多繞幾圈(quan),放進(jin)(jin)鉗口測(ce)量(liang),其(qi)實際電(dian)流(liu)值應為儀表讀(du)數(shu)(shu)除以(yi)(yi)放進(jin)(jin)鉗口內的導線(xian)根數(shu)(shu)。
5、每次(ci)測(ce)量前后,要把調節電流(liu)量程的切(qie)換開關放在(zai)最高檔(dang)位(wei),以免(mian)下次(ci)使用(yong)時(shi),因未經選擇(ze)量程就進行(xing)測(ce)量而損壞儀表。
注意事項
用鉗形電流表檢測電流時,一定要夾入一根被測導線(電線)。夾入兩(liang)根(gen)(平行線(xian))則不(bu)能檢(jian)(jian)(jian)測(ce)(ce)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)。另(ling)外,使用鉗形(xing)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)表(biao)中心(鐵心)檢(jian)(jian)(jian)測(ce)(ce)時(shi),檢(jian)(jian)(jian)測(ce)(ce)誤差小。在檢(jian)(jian)(jian)查家(jia)電(dian)(dian)(dian)(dian)(dian)產品(pin)的(de)耗電(dian)(dian)(dian)(dian)(dian)量(liang)時(shi),使用線(xian)路分離器比較方(fang)便,有的(de)線(xian)路分離器可將檢(jian)(jian)(jian)測(ce)(ce)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)放(fang)大(da)10倍(bei),因此(ci)1A以下的(de)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)可放(fang)大(da)后(hou)再檢(jian)(jian)(jian)測(ce)(ce)。用直流(liu)(liu)(liu)鉗形(xing)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)表(biao)檢(jian)(jian)(jian)測(ce)(ce)直流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(DCA)時(shi),如(ru)果電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)的(de)流(liu)(liu)(liu)向相反(fan),則顯示出負(fu)數。可使用該功(gong)能檢(jian)(jian)(jian)測(ce)(ce)汽車(che)的(de)蓄電(dian)(dian)(dian)(dian)(dian)池是(shi)充(chong)電(dian)(dian)(dian)(dian)(dian)狀態(tai)還是(shi)放(fang)電(dian)(dian)(dian)(dian)(dian)狀態(tai)。
真有效值檢測
平(ping)均值(zhi)(zhi)方式的(de)(de)鉗形(xing)電(dian)流(liu)(liu)(liu)(liu)表通過交流(liu)(liu)(liu)(liu)檢測,檢測正弦(xian)(xian)波(bo)(bo)(bo)的(de)(de)平(ping)均值(zhi)(zhi),并(bing)將(jiang)放大(da)(da)1.11倍(bei)(正弦(xian)(xian)波(bo)(bo)(bo)交流(liu)(liu)(liu)(liu))之后的(de)(de)值(zhi)(zhi)作為有效(xiao)值(zhi)(zhi)顯示出來(lai)。波(bo)(bo)(bo)形(xing)率不同(tong)的(de)(de)正弦(xian)(xian)波(bo)(bo)(bo)以(yi)外(wai)(wai)的(de)(de)波(bo)(bo)(bo)形(xing)和(he)歪波(bo)(bo)(bo)也同(tong)樣放大(da)(da)1.11倍(bei)后顯示出來(lai),所以(yi)會產(chan)生指示誤差。因此檢測正弦(xian)(xian)波(bo)(bo)(bo)以(yi)外(wai)(wai)的(de)(de)波(bo)(bo)(bo)形(xing)和(he)歪波(bo)(bo)(bo)時,請選(xuan)用可直接測試出真有效(xiao)值(zhi)(zhi)的(de)(de)鉗形(xing)電(dian)流(liu)(liu)(liu)(liu)表。
漏電檢測
漏電(dian)(dian)檢(jian)測(ce)(ce)與(yu)通常的電(dian)(dian)流(liu)檢(jian)測(ce)(ce)不(bu)同,兩根(gen)(單相(xiang)2線(xian)式(shi))或三根(gen)(單相(xiang)3線(xian)式(shi),三相(xiang)3線(xian)式(shi))要全部夾住。也可夾住接地線(xian)進行檢(jian)測(ce)(ce)。在低壓電(dian)(dian)路上(shang)檢(jian)測(ce)(ce)漏電(dian)(dian)電(dian)(dian)流(liu)的絕緣管理方法,已成(cheng)為首(shou)要的判斷手段。自其被1997年電(dian)(dian)氣設備(bei)技術標準的修正確認以(yi)來,在不(bu)能停電(dian)(dian)的樓宇和工(gong)廠,便(bian)逐漸采用漏電(dian)(dian)電(dian)(dian)流(liu)鉗表來檢(jian)測(ce)(ce)。