What is the difference between cathodic protection of external power supply and cathodic protection of sacrificial anode?

I. Different principles of BAI:

1, the principle of external power supply of Yin DU electrode protection: through the external zhi current power supply and auxiliary anode, forced dao to make the electron flow from the soil to the protected metal, the protected metal structure potential is higher than the surrounding environment to protect.

2. The principle of cathodic protection at the expense of the anode: the metal with strong reducing property is used as a protective pole, and the metal is connected to the protected metal to form a galvanic cell. The metal with strong reducing property will be used as a negative electrode for oxidation reaction and consumption, and the metal with strong reducing property can be used as a positive electrode to avoid corrosion.

Two, the advantages of the two are different:

1, the advantages of cathode protection of external power supply: the need for large current occasions, especially the protection of exposed or poorly coated structures; All conductive electrolyte solution; For the protection of large heat exchangers in water tanks, oil heating processors and other containers; The inner wall of a water storage tank.

2, sacrifice the advantages of cathodic protection anode: no external power supply; Minimal maintenance; Small current output results in little or no stray current interference; Easy to install; Easy to increase the anode in most cases; Provide uniform current distribution.

Three, the relevant requirements of the two are different:

1. Related requirements of cathode Protection Law for external power supply:

(1) Cathodic protection rectifiers or other power sources shall be installed in such a way as to minimize or minimize the likelihood of damage.

(2) The conductor connected to the rectifier shall comply with the local and national electrical regulations, in accordance with the requirements of the power supply used. External circuit breakers shall be provided in the AC circuit. The rectifier housing shall be reliably grounded.

(3) All cables should be carefully inspected to detect their insulation defects, and care should be taken to prevent damage to the cable insulation, and the cable insulation defects must be repaired.

2. Related requirements for cathodic protection of sacrificial anode:

(1) The potential is negative enough, but not too negative, so as not to produce hydrogen evolution reaction in the cathode region.

(2) The polarization of the anode should be small, and the current output of the potential pole should be stable.

(3) the capacitance of the anode material should be large.

(4) Must have high current efficiency.