Constant current power supplies for Active Corrosion Control

Bridges, ships and offshore wind turbines are three examples where the prevention of corrosion of the structure is very important and greatly reduces operating costs. For environmental reasons, the traditional passive ‘Sacrificial Anode’ method of corrosion control is increasingly being replaced in favour of ‘Active’ prevention, which is implemented by applying an ‘impressed current’.

Figure 1 - Prevention of Corrosion - Sacrificial Anode

In the passive method, the anode of a different metal to the structure is ‘sacrificed’ in order to ensure that the structure is protected from corrosion. In the ‘active’ method, a sophisticated electronic current control system is used to inject a reverse current to that generated from corrosion to protect the structure. Since current flow is closely related to the flow of charge over time ( I = [dQ/dt] ), having constant current control allows the user to accurately control the process.

“In the first case, there is a need to periodically replace the sacrificial anode with consequent costs and dispersion of metals in the water. In the second case, the only costs will be that of the system and the energy used,” comments David Buck, Market Development Manager, TDK-Lambda EMEA.

Figure 2 - Prevention of Corrosion - Impressed Current

The availability of isolated interfaces, analogue, digital RS232/485, IEEE488 and LAN allows a high flexibility of integration and system control. Power ratings range from 200W to 15KW, with the possibility of placing up to four units in parallel to increase the power up to 60KW and output currents up to 4000A. In addition, TDK-Lambda has the capability to optimise a standard product or even develop a custom solution to meet the specific needs of a particular user application.