| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a galvanic anode from causing direct-current interference in peripheral another buried metallic body, without increasing a risk of corrosion of a pipeline, even when the galvanic anode is connected in the vicinity of a portion at which a selection drainage device is placed. <P>SOLUTION: This cathodic protection system includes: inserting a diode 10 in a connecting line L which electrically connects the buried pipeline P with the galvanic anode M; connecting a constant-current control circuit 20 having a switching element 21 which turns the circuit on and off, with the connecting line L so as to be parallel with the diode 10; and providing a monitoring control means 30 which can control on/off of the switching element 21 by monitoring an inter-terminal voltage V of the diode 10 and a main current I of the connecting line L. The monitoring control means 30 turns on the switching element 21 in a state that the inter-terminal voltage V is positive in a forward direction of the diode 10 and is equal to set voltage V<SB>F</SB>or less which exceeds an operating voltage of the diode 10, and determines a corrosion protection condition of the buried pipeline P according to whether the main current I is a value I<SB>C</SB>of a constant current passed from the constant-current control circuit 20 or not. <P>COPYRIGHT: (C)2010,JPO&INPIT |
