What Does Impressed Current Anode Mean?
Impressed current anodes refer to a kind of anode of cathodic protection systems. A cathodic protection system has two types of anodes: a galvanic or sacrificial anode and an impressed current anode.
Impressed current anodes are inert anodes used in impressed current protection in cathodic protection systems. These anodes are powered by the DC current from an external source.
A proper selection of impressed current anodes would include the consideration of the environment that surrounds a buried or submerged structure to control corrosion.
Corrosionpedia Explains Impressed Current Anode
An impressed current anode uses an external power source known as a "rectifier" to develop a high potential difference between the surface to be protected and an anode. The anodes employed are generally made of graphite, cast iron, titanium alloys, silicon iron and platinum-niobium clad metals. Impressed current anodes are found in many sizes and shapes such as wires, rods, tubes, plates and sticks.
Impressed current anodes are less likely to be attacked by corrosion due to their inert nature. The external DC power source is used to generate the electric current and this current provides cathodic protection to the structure. Impressed current systems provide better results when a large current is required for cathodic protection.
Impressed current anodes have some advantages over galvanic anodes, including:
- Achieves a much higher current output
- Fewer anodes are needed
- Involves a low initial cost
Both types of anodes in cathodic protection systems are corroded and eventually consumed. There are inverse relations that exist between the corrosion of anodes and the current output. The voltage output may need to be adjusted to maintain protection. Normally stable anodes, such as a platinum-niobium anode, require less frequent adjustment.