Analysis on Overhead Shielded Coupling Effectiveness of Ring Seam by Matlab

it was important to study the shielded effectiveness to reduce the electromagnetic interference and to protect electronic components. in this paper, the boundary element equation of linear segment was derived from the two-dimension boundary integral equation and linear interpolating function, and the formulas of potential and electric field intensity were also given. To demonstrate the accuracy and flexibility of the LBEM (linear boundary element method), the influence of the deformation degree of shielded deformed coaxial cable compared with the multipole theory on the results were discussed. Taking the overhead shielded coaxial cable and the overhead shielded two-core cable of ring seam as the research objects. The influences of ring seam in shielded effectiveness were analyzed by applying the LBEM with Matlab. The engineering example results showed that for overhead shield two-core cable, the change of coupling capacitance was related with the ring seam in deep layer of overhead shield two-core cable at the location of parallel core distance; and the change tendency of coupling capacitor with the ring seam at the vertical core distance was almost the same as the ring seam at the parallel core distance. But, when the ring seam depth was quite deep, very likely one core was exposed, and then the coupling capacitor decreased rapidly. Therefore the study of coupling effectiveness was instructive for more effective to defense EMI and will improve the overhead shielded cable electromagnetic compatibility.