Method and apparatus for measuring the polarized potential of a buried or submerged structure protected by impressed current

摘要

The polarized potential at the boundary between a submerged pipe and a medium is measured unaffected by the presence of a distributed IR drop in the medium due to an impressed current from a corrosion protection system. The voltage between the pipe and a reference electrode in the medium is measured when the protection system current is zero. This is accomplished with a sample-and-hold circuit controlled by a trigger signal derived from the input signal and having a variable phase for controlling the phase angle at which the sample is taken.