Diagnosis of reference electrodes in cathodic protection systems by electrochemical impedance spectroscopy

Laboratory and field investigation results have been presented of cathodic protection installation elements of an underground steel pipeline by the electrochemical impedance spectroscopy (EIS) technique. Impedance spectra have been presented of the following systems: reference electrode/auxiliary electrodes, pipeline/buried and portable reference electrodes. It has been shown that the discussed technique makes it possible to investigate the technical state of reference electrodes, allowing evaluation of the reliability of potential measurement results of the protected structure. EIS gives information unavailable through traditional DC measurement techniques used in cathodic protection installations. It allows, for example, determination of the resistance of the system: structure/reference electrode. This can be used for estimation of the potential IR component.