There are several factors to keep in mind when selecting a mitigation system that involves AC and lightning interference voltages and currents in pipelines. The system should do the following: Consider the effects of both normal and abnormal power system conditions; Integrate with the CP (cathodic protection) system and user practices; Minimize the introduction of secondary problems; Spot mitigation is very useful for minimizing steady-state-induced AC voltages and touch and step potentials at specific spots along a pipeline. However, it will not protect pipeline coatings exposed to abnormal operating conditions such as AC faults or lightning from nearby power line structures. Continuous mitigation is more suitable for this purpose. There are some advantages to using a decoupling device between the pipeline and the wire or ribbon: Allows the use of lower cost materials for the AC mitigation grounding system Simplifies both the impressed current CP system and the voltage mitigation by separating the safety and protection systems. For continuous mitigation, there are different material options: Directly bonded zinc or magnesium, isolated copper, isolated zinc or magnesium. For any AC mitigation project, a thorough economic analysis should take into account the costs of the CP system and the mitigation system for each mitigation alternative because one can affect the other.
AC mitigation using shield wires and decoupling devices
Materials Performance ; 47 , 5 ; 36-39
2008
4 Seiten, 3 Quellen
Article (Journal)
English
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