THE DISTRIBUTION OF MAGNETIC AND THERMAL FIELDS, POWER LOSSES IN ELECTROMAGNETIC SHIELD OF UNDERGROUND TWO-CIRCUIT CABLE LINE

Abstract

In the article, the magnetic and thermal field distributions generated by underground two-circuit extra-high voltage power cable line in the environment, particularly near the cables and flat aluminum shield, which is located at a different distance from the cables and has different thicknesses, are analyzed. The unique features of the magnetic field and temperature distributions inside the shield are computed and studied. For the cases under consideration, the Joule losses in the external shield do not exceed 3% of the losses in the cables. The primary electromagnetic characteristics are compared for the aluminum shield (shielding efficiency is 1,94) and the shield with lower conductivity (shielding efficiency is equal to 1,2). As shown, the thicker shield helps to increase the ampacity of the cable line owing to lower heating. The actual operating current of the cable line under consideration depends on the distance of the shield from the cables owing to the relation between their maximum temperature and this distance. Ref. 15, fig. 7, table.