以(yi)(yi)管(guan)道(dao)作為陽極(ji)(ji)(ji)，從(cong)外部(bu)通入(ru)(ru)電(dian)(dian)(dian)(dian)流(liu)，一(yi)般將(jiang)加速腐蝕(shi)，腐蝕(shi)電(dian)(dian)(dian)(dian)流(liu)隨陽極(ji)(ji)(ji)極(ji)(ji)(ji)化(hua)(hua)而增大。但是對可(ke)以(yi)(yi)鈍化(hua)(hua)的(de)(de)金(jin)屬則會(hui)出現(xian)另一(yi)情況(kuang)，當電(dian)(dian)(dian)(dian)位(wei)隨電(dian)(dian)(dian)(dian)流(liu)上(shang)升(sheng)，達到(dao)致(zhi)鈍電(dian)(dian)(dian)(dian)位(wei)后，腐蝕(shi)電(dian)(dian)(dian)(dian)流(liu)急速下降，甚至可(ke)下降幾萬(wan)倍，以(yi)(yi)后隨電(dian)(dian)(dian)(dian)位(wei)上(shang)升(sheng)，電(dian)(dian)(dian)(dian)流(liu)不(bu)變(bian)，直到(dao)過鈍區為止。利用這個(ge)原理Edleanu 首(shou)先(xian)提出陽極(ji)(ji)(ji)保護的(de)(de)概念，以(yi)(yi)需要保護的(de)(de)設(she)備(bei)為陽極(ji)(ji)(ji)，導入(ru)(ru)電(dian)(dian)(dian)(dian)流(liu)，使電(dian)(dian)(dian)(dian)位(wei)保持在鈍化(hua)(hua)區的(de)(de)中段（以(yi)(yi)免波動時(shi)進入(ru)(ru)活化(hua)(hua)區），腐蝕(shi)速率可(ke)保持很(hen)低值，通入(ru)(ru)的(de)(de)電(dian)(dian)(dian)(dian)流(liu)就表示設(she)備(bei)的(de)(de)腐蝕(shi)速率。這種(zhong)方法需要一(yi)臺恒電(dian)(dian)(dian)(dian)位(wei)儀(yi)，用以(yi)(yi)控制設(she)備(bei)的(de)(de)電(dian)(dian)(dian)(dian)位(wei)。因為它只(zhi)適用于接觸鈍化(hua)(hua)溶液(ye)的(de)(de)可(ke)鈍化(hua)(hua)金(jin)屬，所以(yi)(yi)用途受限制。工業(ye)上(shang)已用于處理硫酸、磷酸、碳(tan)酸氫銨生(sheng)產液(ye)、硝銨混肥等的(de)(de)不(bu)銹鋼或碳(tan)鋼制的(de)(de)各種(zhong)管(guan)道(dao)設(she)備(bei)。