Analytical Calculation of Magnetic Field Shielding Factor for Cable Line with Two-Point Bonded Shields

In this paper we present an analytical model of the magnetic field of a high-voltage three-phase cable line with two-point bonded shields. The cable line is assumed to consist of three single-core XLPE insulated cables. The represented analytical model allows to calculate the electric currents induced in shields of cables and to determine the magnetic field distribution for the arbitrary layout of cables. We obtain an exact compact expression for the magnetic field shielding factor for the trefoil cable line with two-point bonded shields. Also we obtain a simplified compact expression for the magnetic field shielding factor for the flat cable line with two-point bonded shields. We show that the difference of the simplified expression with the exact analytical expression and experimental results is within 4 %.