Vermont Electric needed a new 345 kV H-frame transmission line design approximately 54 miles in length in mountainous terrain in Vermont for the purpose of reinforcing the existing transmission grid system. The new 345 kV transmission line is paralleling an existing 345 kV line. The new line has a loop interconnecting into a new substation. The new line was designed to match the existing structure location and type of structure as closely as possible, as well as to avoid environmentally sensitive areas.
The design criteria of the old line had to be recreated in order to match the old code design to the current code design, hence match the existing 345 kV design. New steel poles were designed for use in selected areas. Also, existing Vermont River crossing structures were analyzed as part of this project. Modifications to the existing guying had to occur so there is not interference with the new parallel line. The conductor was two-bundle 954 kcmil “Rail” ACSR. PLS-CADD was used for the routing, permitting, and design phases of this project.