Comparison of Screening Configurations for the Mitigation of Voltages and Currents Induced on Pipelines by HVAC Power Lines

In this paper, a strategy for reducing the electromagnetic interferences induced by power lines on metallic pipelines is proposed and numerically investigated. The study considers a set of steel conductors interposed between the power line and the pipeline. Different shapes of conductor cross sections and different magnetic permeabilities are considered, to identify the solution exhibiting the greatest mitigation efficiency for the same amount of material. The investigation is carried out by means of a quasi-3D finite element analysis. Results show that the main mechanism responsible for the mitigation is constituted by the currents induced in the screening conductors by the power line. Hence, a high magnetic permeability can have a detrimental effect since it reduces the skin depth to values below the size of the screening conductor. In this case, a reduction of the screening current and in the mitigation efficiency is observed. Nevertheless, the study shows that the use of strip-shaped screening conductors allows the employment of cheaper magnetic materials without compromising the mitigation efficacy of the screening conductors.

Magnetic Flow Scattering in Ferrite Rings

It is shown that, contrary to the prevailing opinion, the scattering of the magnetic flux, even in ferrites with high magnetic permeability, is very large. A description of the technique for measuring the parameters of ferrites and inductors on ferrite rings is given. The results of experimental measurements of parameters for various grades of ferrites and various values of magnetic permeability are presented. Recommendations on the design of high-frequency transformers and inductors on ferrite rings are given.

SANDVIK SAFENI 52

Safeni 52 is a soft magnetic iron-nickel alloy with high magnetic permeability, low coercive force, a low content of nonmetallic inclusions, and thermal expansion properties that make it suitable for glass-sealing applications. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on forming and heat treating. Filing Code: Fe-161. Producer or source: Sandvik Steel Company.