Optimized post-type spacers for 3-phase SF6 insulated cables

If power cables insulated with compressed SF6 gas are to have widespread application, their installed cost must be substantially reduced from the present level. The 3-phase, as opposed to the single-phase, configuration has been viewed as a means for reducing cable cost since it allows the use of materials for the outer pipe which are less onerous to purchase and install.^1,2 Another item affecting the cost of such a cable is the solid dielectric spacer required at frequent intervals to support the conductors. Post-type spacers, which are inherently less voluminous and easier to manufacture than the disc-type or cone-type spacer configurations commonly used in isolated-phase bus construction, offer the possibility of realizing appreciable economies, provided they are optimally designed. This paper reports on the development of a design method intended to minimize the volume of post-type spacers for 3-phase SF6 gas-insulated cables.