以(yi)(yi)管道作為陽極，從外部通入(ru)(ru)電(dian)(dian)(dian)流，一(yi)般將(jiang)加速(su)腐蝕，腐蝕電(dian)(dian)(dian)流隨(sui)陽極極化(hua)而(er)增大。但是對可以(yi)(yi)鈍(dun)化(hua)的(de)(de)金(jin)屬則(ze)會出現(xian)另一(yi)情況，當電(dian)(dian)(dian)位(wei)隨(sui)電(dian)(dian)(dian)流上(shang)升，達到致(zhi)鈍(dun)電(dian)(dian)(dian)位(wei)后，腐蝕電(dian)(dian)(dian)流急速(su)下降，甚至可下降幾(ji)萬(wan)倍，以(yi)(yi)后隨(sui)電(dian)(dian)(dian)位(wei)上(shang)升，電(dian)(dian)(dian)流不變，直到過鈍(dun)區(qu)為止。利(li)用(yong)這個原理(li)Edleanu 首先提出陽極保(bao)護的(de)(de)概念，以(yi)(yi)需要保(bao)護的(de)(de)設(she)備(bei)為陽極，導入(ru)(ru)電(dian)(dian)(dian)流，使電(dian)(dian)(dian)位(wei)保(bao)持(chi)在鈍(dun)化(hua)區(qu)的(de)(de)中段（以(yi)(yi)免波動時進(jin)入(ru)(ru)活化(hua)區(qu)），腐蝕速(su)率可保(bao)持(chi)很低值，通入(ru)(ru)的(de)(de)電(dian)(dian)(dian)流就(jiu)表示設(she)備(bei)的(de)(de)腐蝕速(su)率。這種(zhong)方法需要一(yi)臺恒電(dian)(dian)(dian)位(wei)儀，用(yong)以(yi)(yi)控(kong)制設(she)備(bei)的(de)(de)電(dian)(dian)(dian)位(wei)。因為它(ta)只(zhi)適用(yong)于接觸鈍(dun)化(hua)溶液的(de)(de)可鈍(dun)化(hua)金(jin)屬，所以(yi)(yi)用(yong)途受限制。工業(ye)上(shang)已用(yong)于處理(li)硫酸(suan)、磷酸(suan)、碳酸(suan)氫銨(an)生產液、硝(xiao)銨(an)混肥等的(de)(de)不銹鋼或碳鋼制的(de)(de)各種(zhong)管道設(she)備(bei)。