Semi-flexible gas-insulated transmission line using electric field stress shields

#This invention relates generally to gas-insulated electrical apparatus, and more particularly to a semi-flexible gas-insulated transmission line which utilizes stress shields to control electric field gradients along the transmission line.

#Prior art gas-insulated transmission lines typically comprise a hollow, rigid elongated outer sheath at low or ground electrical potential, with a rigid inner conductor disposed within the outer sheath for carrying the electric current. Insulating supports are utilized for supporting the inner conductor within the outer sheath, and an insulating gas, typical of which is sulfur hexafluoride, is utilized for electrically insulating the high potential inner conductor from the grounded outer sheath.

#One disadvantage which exists with the present gas-insulated transmission line is the inability of the lines to change direction easily. The present lines are composed of straight sections generally 30-60 feet in length, and changes in direction must be accomplished by fabricating a shorter line section and utilizing elbow sections, or their equivalent, to accomplish the change in direction. It therefore would be advantageous to manufacture and utilize a gas-insulated transmission line which can more readily accommodate changes in line direction.

#Reference is now made to the description of the preferred embodiments, illustrated in the accompanying drawings, in which:

#FIG. 1 is a view, in section, of a gas-insulated transmission line utilizing the teachings of this invention;

#FIG. 2 is a detailed sectional view of the transmission line showing the connection of the stress shields;

#Referring now more particularly to FIG. 1, therein is illustrated a compressed gas-insulated transmission line 10 illustrating the teachings of this invention. The transmission line 10 is comprised of an elongated outer sheath 12 which is corrugated to provide flexibility, and an elongated, generally cylindrical inner conductor 14 disposed within the outer sheath. A plurality of spaced insulating supports 16 are utilized for insulatably supporting the inner conductor 14 within the outer sheath 12, and an insulating gas 18, typical of which is sulfur hexafluoride at pressures of 50 pounds/square inch gauge, is used for electrically insulating the inner conductor 14 from the outer sheath 12.

#The inner conductor 14 is comprised of longitudinally spaced apart cylindrical main conductor sections 20 which each have the same diameter 22 and which have facing ends 24, 26, for example (see FIG. 2). A flexing element 28, illustrated in FIG. 2 as being a flat disc with an opening 30 therethrough, is fixedly secured, by means such as the weld 32, to the conductor end 24, and a similar flexing element 34 with an opening 50 is fixedly secured by means such as the weld 36 to the conductor end 26. As shown, each flexing element 28, 34 extends radially inwardly from the main conductor section end 24, 26, respectively, to which it is secured.

#A cylindrical conductor hub section 38, which has an outer diameter 40 less than the inner diameter 22 of the main conductor sections 20, is fixedly secured to the two flexing elements 28, 34 by means such as the welds 42, 44 adjacent the ends 46, 48 of the conductor hub section 38. By being so located, the conductor hub section 38 extends through the openings 30, 50 of the flat disc flexing elements 28, 34.