A, open circuit potential measurement
Before measuring the open circuit potential of the sacrificial anode, the connection between the sacrificial anode and the pipeline should be disconnected first, and the measured potential is the open circuit potential of the sacrificial anode. If it is found that the positive deviation of the open circuit potential is serious, it may be caused by the dry soil environment and the oxidation products on the anode surface attached to the surface, or it may be caused by the poor quality of the anode. The open circuit potential of the magnesium anode should be negative to -1.5Vcse, and that of the zinc anode should be negative to -1.05Vcse.
Two, closed circuit potential measurement
The potential measured after the sacrificial anode is connected to the pipe is the closed circuit potential of the anode. After turning on the cathodic protection power and polarization for 24 hours, the measured data is more accurate. For measurement, the reference electrode should be longitudinal along the pipe and at least 5m away from the sacrificial anode edge.
Three, output current measurement
(1) Clamp ammeter can be used to measure the anode output current directly on the anode cable. In order to improve the measurement accuracy, the wire can be wrapped on the measuring clamp more than a few turns of current as the measured value divided by the number of turns. (2) The standard resistance with 0.1 ohm is connected in series in the loop to measure the power supply and calculate the current. (3) Directly connect the ammeter in series in the circuit to measure the current. But affected by the internal resistance of ammeter, the value measured by direct series ammeter will be less than the actual value.
