METHOD FOR MEASUREMENT OF POLARISATION POTENTIAL OF METAL UNDERGROUND STRUCTURES Russian patent published in 2009 - IPC G01R27/20 

FIELD: physics.

SUBSTANCE: method for measurement of polarisation potential of metal underground structures by measurement of difference of "pipe-ground" potentials consists in the following: measuring instrument is connected between cathode lead and comparison electrode installed on ground surface above pipeline axis (or near). Measurement of polarisation potential is carried out after disconnection of protective current after short period of time expires required for exclusion of transitional processes effect. Multirange millivoltmeter is used in inlet resistance of at least 1.0 MOhm to measure difference of potentials between cathode (pipe) and nonpolarisable comparison electrode installed at the first station of measurement, afterwards all subsequent measurements of potentials difference are carried out between comparison electrodes installed in the first and second measurement stations, and further between comparison electrodes of every preceding and subsequent measurement stations along pipeline length. In process of measurements one and the same terminal of voltmeter is connected to cathode and further to all preceding comparison electrodes. To obtain value of polarisation potential of station No. N, all readings of millivoltmeter obtained from the first measurement to station No. N are summed up with as cumulative sum with account of measured potentials sign, and comparison electrode potential is subtracted from sum. In order to reduce effect of soil heterogeneity, measurements are done in section with pitch of up to 100 m.

EFFECT: efficient measurement of polarisation potential of metal underground structures.