GB502122A - Improvements in electric cables having shielded conductors - Google Patents

Abstract

502,122. Cables. STANDARD TELEPHONES & CABLES, Ltd. (Western Electric Co., Inc.) Oct. 19, 1937, No. 28461. [A Specification was laid open to inspection under Sect. 91 of the Acts, July 27, 1938.] [Class 36] A cable comprises a plurality of conductor units with a predetermined thickness of shield between any two units to provide a predetermined shielding effect, each unit being surrounded by a shield giving a part of the required shield effect between one unit and another, and the shields being so arranged that the sum of the shielding effects of the shields around any two units is equal to the shielding effect required between these Units. The shield may be of composite formation comprising iron and copper, the iron being applied to one unit and the copper to the other; alternatively, each unit may be surrounded by a layer of copper and a layer of iron, the copper layers being of " critical thickness," viz. : À001 to À01 inch thick. The copper and iron layers may consist of tapes lapped on the units. Fig. 6 shows a cable comprising conductor units A-G all enclosed in a lead sheath L and each surrounded by a " half shield " comprising an inner copper layer Cu of not more than critical thickness and an outer iron layer Fe. A common screen S surrounds the several units and comprises a critically thick outer copper layer and an inner iron layer. British Specifications 351,491 and 480,536, and U.S.A. Specification 1,933,261 are referred to.