Patent ID: 7265559

Claim:
A loop-powered corrosion measurement device for measuring or monitoring corrosion of a structure exposed to an electrolyte, comprising: a loop interface coupleable to a 4-20 mA loop and comprising a power system to power the device using power from the 4-20 mA loop; a probe interface system with signal conditioning circuitry to interface with a plurality of measurement electrodes situated in the electrolyte, the signal conditioning circuitry comprising: excitation circuitry operative to provide an AC excitation signal to the electrolyte via a first one of the electrodes, and sensing circuitry operative to sense one or more corrosion-related electrical signals via at least a second one of the electrodes; and a processing system operatively coupled with the probe interface system to control the excitation signal provided to the electrolyte and to compute an electrolyte resistance value in each of a series of device cycles based on signals sensed by the sensing circuitry, wherein the processing system provides the excitation signal at a first amplitude and selectively increases the excitation signal amplitude until a resulting sensed signal exceeds a predefined threshold value.