國際上應用(yong)(yong)的(de)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)具有一(yi)(yi)個標準規范,國際上規定熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)分(fen)為(wei)(wei)八個不(bu)(bu)同(tong)的(de)分(fen)度(du),分(fen)別為(wei)(wei)B,R,S,K,N,E,J和(he)(he)T,其測量溫(wen)度(du)的(de)最低可測零下270攝(she)氏度(du),最高可達1800攝(she)氏度(du),其中(zhong)B,R,S屬(shu)(shu)于鉑(bo)系列的(de)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou),由(you)于鉑(bo)屬(shu)(shu)于貴(gui)重金(jin)(jin)屬(shu)(shu),所以他們又被(bei)稱為(wei)(wei)貴(gui)金(jin)(jin)屬(shu)(shu)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)而(er)剩(sheng)(sheng)下的(de)幾個則稱為(wei)(wei)廉價金(jin)(jin)屬(shu)(shu)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)。熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)的(de)結構有兩種(zhong)(zhong),普(pu)通型(xing)和(he)(he)鎧裝型(xing)。普(pu)通性熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)一(yi)(yi)般(ban)(ban)由(you)熱(re)(re)(re)電(dian)(dian)極(ji),絕緣管,保(bao)護套管和(he)(he)接(jie)線(xian)(xian)(xian)(xian)(xian)(xian)盒(he)等(deng)部分(fen)組成,而(er)鎧裝型(xing)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)則是(shi)將熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)絲,絕緣材(cai)料和(he)(he)金(jin)(jin)屬(shu)(shu)保(bao)護套管三者組合裝配后,經過(guo)拉伸加工(gong)而(er)成的(de)一(yi)(yi)種(zhong)(zhong)堅實的(de)組合體。但(dan)是(shi)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)的(de)電(dian)(dian)信號(hao)卻需要一(yi)(yi)種(zhong)(zhong)特(te)殊的(de)導(dao)線(xian)(xian)(xian)(xian)(xian)(xian)來(lai)進行傳遞,這種(zhong)(zhong)導(dao)線(xian)(xian)(xian)(xian)(xian)(xian)我們稱為(wei)(wei)補(bu)(bu)(bu)償導(dao)線(xian)(xian)(xian)(xian)(xian)(xian)。不(bu)(bu)同(tong)的(de)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)需要不(bu)(bu)同(tong)的(de)補(bu)(bu)(bu)償導(dao)線(xian)(xian)(xian)(xian)(xian)(xian),其主要作用(yong)(yong)就(jiu)是(shi)與(yu)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)連接(jie),使熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)的(de)參比端遠離電(dian)(dian)源,從(cong)而(er)使參比端溫(wen)度(du)穩定。補(bu)(bu)(bu)償導(dao)線(xian)(xian)(xian)(xian)(xian)(xian)又分(fen)為(wei)(wei)補(bu)(bu)(bu)償型(xing)和(he)(he)延(yan)長型(xing)兩種(zhong)(zhong),延(yan)長導(dao)線(xian)(xian)(xian)(xian)(xian)(xian)的(de)化(hua)學成分(fen)與(yu)被(bei)補(bu)(bu)(bu)償的(de)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)相(xiang)同(tong),但(dan)是(shi)實際中(zhong),延(yan)長型(xing)的(de)導(dao)線(xian)(xian)(xian)(xian)(xian)(xian)也并(bing)不(bu)(bu)是(shi)用(yong)(yong)和(he)(he)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)相(xiang)同(tong)材(cai)質的(de)金(jin)(jin)屬(shu)(shu),一(yi)(yi)般(ban)(ban)采用(yong)(yong)和(he)(he)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)具有相(xiang)同(tong)電(dian)(dian)子(zi)密度(du)的(de)導(dao)線(xian)(xian)(xian)(xian)(xian)(xian)代(dai)替。補(bu)(bu)(bu)償導(dao)線(xian)(xian)(xian)(xian)(xian)(xian)的(de)與(yu)熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)的(de)連線(xian)(xian)(xian)(xian)(xian)(xian)一(yi)(yi)般(ban)(ban)都是(shi)很明了(le),熱(re)(re)(re)電(dian)(dian)偶(ou)(ou)(ou)(ou)(ou)(ou)(ou)(ou)的(de)正極(ji)連接(jie)補(bu)(bu)(bu)償導(dao)線(xian)(xian)(xian)(xian)(xian)(xian)的(de)紅(hong)色線(xian)(xian)(xian)(xian)(xian)(xian),而(er)負極(ji)則連接(jie)剩(sheng)(sheng)下的(de)顏色。一(yi)(yi)般(ban)(ban)的(de)補(bu)(bu)(bu)償導(dao)線(xian)(xian)(xian)(xian)(xian)(xian)的(de)材(cai)質大部分(fen)都采用(yong)(yong)銅鎳合金(jin)(jin)。
鎧裝熱電偶和工業用裝配式熱電偶一樣,作為測量溫度的傳感器,通常和顯示儀表、記錄儀表和電子調節器配套使用,同時,亦可以作為裝配式熱電偶的感溫元件。它可以直接測量各種生產過程中從0℃~800℃范圍內的液體、蒸汽和其氣體介質以及固體表面的溫度。與裝配式熱電偶相比,鎧裝熱電偶具有可彎曲、耐高壓、熱響應時間短和堅固耐用等優點。
由于鎧裝熱電偶的材料一般都比較貴重(特別是采用貴金屬時),而測溫點到儀表的距離都很遠,為了節省鎧裝熱電偶材料,降低成本,通常采用補償導線把鎧裝熱電偶的冷端(自由端)延伸到溫度比較穩定的控制室內,連接到儀表端子上。必須指出,熱電偶補償導線的作用只起延伸熱電極,使鎧裝熱電偶的冷端移動到控制室的儀表端子上,它本身并不能消除冷端溫度變化對測溫的影響,不起補償作用。因此,還需采用其他修正方法來補償冷端溫度t0≠0℃時對測溫的影響。 在使用鎧裝熱電偶補償導線時必須注意型號相配,極性不能接錯,補償導線與鎧裝熱電偶連接端的溫度不能超過100℃。