If the applied voltage such as IR drop in soil is not considered, the potential measurement of pipeline and tank in soil will be wrong. In general, under the flow of protection current, the electrified potential of the protected device is measured corresponding to the reference electrode installed on the ground above the protected object. When measuring the polarization state, it is necessary to eliminate the IR drop component contained in the electrified potential. In this method, the current must be changed, but in the case of stray current caused by DC electric railway, this is impossible.
When measuring the power-off potential of cathodic protection pipeline, the time relay is installed in the cathodic protection station, which can synchronize with the adjacent protection station and interrupt the protection current for 3S every 30s. The synchronous operation of the protection station is completed as follows: the timing switch is installed in the first protection station, and the interruption of protection current can be detected from the change of tube ground potential in the next protection station. Since the transfer time is known, the timing switch on the second protection station can be activated synchronously. Other protection stations can realize synchronous conversion in the same way.
Other timing switch devices work with electronic digital clock. The cumulative counter counts according to the 1s time interval obtained by the power frequency, and the power on time can be set as required. All protection systems can be completely synchronized with the transmitted pulse. It is recommended that all instruments be equipped with additional timing switches, so that the protection current does not have to be maintained outside the working hours.
In the analysis of the results of cathodic protection pipeline, in addition to the on and off potential, pipe current, insulation point resistance and the resistance between casings, the protection current density and coating resistance should be calculated according to each pipe section of the pipeline.
Shandong Linyi Bosi conductive materials Co., Ltd. is a high-tech enterprise specializing in the production of MMO flexible anode, conductive polymer flexible anode and titanium coated anode, mainly providing cathodic protection technology, engineering design, installation and technical services. Tel: 0539 3712117, 15588026668.