Minimizing the Magnetic Field Surrounding Isolated-Phase Bus by Electrically Continuous Enclosures

This paper describes a bus with electrically continuous phase enclosures interconnected at both ends. Currents in the shielding loop thus formed reduce external magnetic flux to less than one tenth the amount experienced with a discontinuous sheath. Circulating currents in nearby metallic loops are greatly reduced thereby, making joint insulation and banding of steel beams unnecessary. Over-all sheath losses are practically unchanged, for shielding current losses are approximately balanced by substantial elimination of sheath eddy-current losses. Analytical predictions are confirmed by tests.