No matter which protection method is adopted, the ideal state is that the polarization potential of the protected object is lower than the corrosion potential and greater than -100mV, while the current loss should not be too large;
For example, the corrosion potential of steel is -700mV, so the protection potential of steel pipeline is generally not less than -0.85V. If the protection current is too large, it will not only cause the overload of the output unit, but also greatly shorten the protection range of cathodic protection station or sacrifice, so that some pipe sections will lose protection. Good insulation of both ground and unprotected segments can greatly reduce the leakage current.