熱電偶是(shi)一(yi)種(zhong)感溫(wen)(wen)(wen)元件 , 它把溫(wen)(wen)(wen)度(du)(du)(du)(du)信號(hao)轉(zhuan)換(huan)(huan)成(cheng)熱電(dian)(dian)(dian)動(dong)勢(shi)(shi)(shi)信號(hao) , 通(tong)過電(dian)(dian)(dian)氣儀表(biao)轉(zhuan)換(huan)(huan)成(cheng)被測介質的(de)(de)(de)(de)(de)溫(wen)(wen)(wen)度(du)(du)(du)(du)。熱電(dian)(dian)(dian)偶(ou)(ou)測溫(wen)(wen)(wen)的(de)(de)(de)(de)(de)基(ji)本原理是(shi)兩(liang)種(zhong)不同成(cheng)份的(de)(de)(de)(de)(de)均質導體組成(cheng)閉合回(hui)路(lu)(lu) , 當(dang)兩(liang)端(duan)存在溫(wen)(wen)(wen)度(du)(du)(du)(du)梯度(du)(du)(du)(du)時 , 回(hui)路(lu)(lu)中(zhong)(zhong)就(jiu)(jiu)會(hui)有(you)(you)電(dian)(dian)(dian)流通(tong)過，此(ci)時兩(liang)端(duan)之(zhi)間就(jiu)(jiu)存在 Seebeck 電(dian)(dian)(dian)動(dong)勢(shi)(shi)(shi)——熱電(dian)(dian)(dian)動(dong)勢(shi)(shi)(shi)，這就(jiu)(jiu)是(shi)所謂的(de)(de)(de)(de)(de)塞貝克效(xiao)應。兩(liang)種(zhong)不同成(cheng)份的(de)(de)(de)(de)(de)均質導體為(wei)(wei)熱電(dian)(dian)(dian)極，溫(wen)(wen)(wen)度(du)(du)(du)(du)較(jiao)高的(de)(de)(de)(de)(de)一(yi)端(duan)為(wei)(wei)工作端(duan)， 溫(wen)(wen)(wen)度(du)(du)(du)(du)較(jiao)低(di)的(de)(de)(de)(de)(de)一(yi)端(duan)為(wei)(wei)自(zi)(zi)由端(duan)，自(zi)(zi)由端(duan)通(tong)常處于某(mou)個恒定的(de)(de)(de)(de)(de)溫(wen)(wen)(wen)度(du)(du)(du)(du)下(xia)。根(gen)據熱電(dian)(dian)(dian)動(dong)勢(shi)(shi)(shi)與溫(wen)(wen)(wen)度(du)(du)(du)(du)的(de)(de)(de)(de)(de)函數(shu)關系 , 制成(cheng)熱電(dian)(dian)(dian)偶(ou)(ou)分(fen)度(du)(du)(du)(du)表(biao) ; 分(fen)度(du)(du)(du)(du)表(biao)是(shi)自(zi)(zi)由端(duan)溫(wen)(wen)(wen)度(du)(du)(du)(du)在 0 ℃ 時 的(de)(de)(de)(de)(de)條件下(xia)得到的(de)(de)(de)(de)(de)，不同的(de)(de)(de)(de)(de)熱電(dian)(dian)(dian)偶(ou)(ou)具(ju)有(you)(you)不同的(de)(de)(de)(de)(de)分(fen)度(du)(du)(du)(du)表(biao)。在熱電(dian)(dian)(dian)偶(ou)(ou)回(hui)路(lu)(lu)中(zhong)(zhong)接(jie)(jie)入(ru)第三種(zhong)金屬(shu)材料時 , 只(zhi)要該(gai)材料兩(liang)個接(jie)(jie)點的(de)(de)(de)(de)(de)溫(wen)(wen)(wen)度(du)(du)(du)(du)相同 , 熱電(dian)(dian)(dian)偶(ou)(ou)所產(chan)生(sheng)的(de)(de)(de)(de)(de)熱電(dian)(dian)(dian)勢(shi)(shi)(shi)將保持不變，即(ji)不受第三種(zhong)金屬(shu)接(jie)(jie)入(ru)回(hui)路(lu)(lu)中(zhong)(zhong)的(de)(de)(de)(de)(de)影響。因(yin)此(ci) , 在熱電(dian)(dian)(dian)偶(ou)(ou)測溫(wen)(wen)(wen)時 , 可接(jie)(jie)入(ru)測量儀表(biao) , 測得熱電(dian)(dian)(dian)動(dong)勢(shi)(shi)(shi)后 , 即(ji)可知道被測介質的(de)(de)(de)(de)(de)溫(wen)(wen)(wen)度(du)(du)(du)(du)。

熱電偶是工業中常用的溫度測溫元件，具有如下特點：
① 測量精度高：熱電偶與被測對象直接接觸，不受中間介質的影響。
② 熱響應時間快：熱電偶對溫度變化反應靈敏。
③ 測量范圍大：熱電偶從 -40~+ 1600℃ 均可連續測溫。
④性能可靠， 機械強度好。
⑤ 使用壽命長，安裝方便。

（ 1 ）熱電偶的種類
熱電偶有 K 型（鎳鉻 - 鎳硅） WRN 系列， N 型（鎳鉻硅 - 鎳硅鎂） WRM 系列， E 型（鎳鉻 - 銅鎳） WRE 系列， J 型（鐵 - 銅鎳） WRF 系列， T 型（銅 - 銅鎳） WRC 系列， S 型（鉑銠 10- 鉑） WRP 系列， R 型（鉑銠 13- 鉑） WRQ 系列， B 型（鉑銠 30- 鉑銠 6 ） WRR 系列等。
（ 2 ）熱電偶的結構形式：
熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)的基本結構(gou)是熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)極(ji)，絕緣材料(liao)和保(bao)護管；并(bing) 與顯示(shi)儀(yi)(yi)表、記(ji)錄儀(yi)(yi)表或計算機等(deng)配(pei)套使用(yong)(yong)(yong)(yong)。在(zai)現場(chang)使用(yong)(yong)(yong)(yong)中根據(ju)環境，被測介質等(deng)多種因(yin)素研制成適合各種環境的熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)。 熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)簡單分(fen)為(wei)裝(zhuang)(zhuang)配(pei)式熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，鎧裝(zhuang)(zhuang)式熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)和特殊形式熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)；按使用(yong)(yong)(yong)(yong)環境細分(fen)有(you)耐(nai) 高(gao)溫熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，耐(nai)磨熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，耐(nai)腐熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，耐(nai)高(gao)壓熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，隔爆熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，鋁(lv)液測溫用(yong)(yong)(yong)(yong)熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，循環硫(liu)化床用(yong)(yong)(yong)(yong)熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，水泥回轉窯爐(lu)(lu)用(yong)(yong)(yong)(yong)熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，陽極(ji)焙燒爐(lu)(lu)用(yong)(yong)(yong)(yong)熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，高(gao)溫熱(re)(re)(re)(re)(re)風(feng)爐(lu)(lu)用(yong)(yong)(yong)(yong)熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，汽(qi)化爐(lu)(lu)用(yong)(yong)(yong)(yong)熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，滲碳(tan)爐(lu)(lu)用(yong)(yong)(yong)(yong)熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，高(gao)溫鹽浴爐(lu)(lu)用(yong)(yong)(yong)(yong)熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，銅、鐵及鋼水用(yong)(yong)(yong)(yong)熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，抗氧化鎢錸(lai)熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，真空爐(lu)(lu)用(yong)(yong)(yong)(yong)熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)，鉑銠熱(re)(re)(re)(re)(re)電(dian)(dian)(dian)(dian)(dian)偶(ou)(ou)(ou)(ou)等(deng)。

；景向前