The project consisted of replacing the phase conductors on the 1 km Acamac Double Circuit crossing on the 1147 & 1165 – 138kV transmission line at South Bay in Saint John, NB, with high temperature low sag ACSS conductor to alleviate a thermal constraint on the power system. The structures spanning the crossing included two 180’ double circuit lattice steel suspension towers (erected in 1976) along with two double circuit lattice steel dead-end structures with dual overhead ground wires (OHGW). The new 395.5 kcmil, Lark/ACSS/HS285 conductor was installed to allow the usage of 100MW of extra loading. The installation of aerial attachments as well as tower painting was also completed.
- Work was required to be completed within allotted 7-day outage windows on each respective circuit. Adequate preparation and identification of risks during the planning stage of the project were needed to ensure the work was executed efficiently and milestone dates were met.
- Vehicle access was not adequate for the two suspension structures; therefore, ladders and unclip-off ladders were utilized to access the conductor.
Specialized Work Methods
- Forty nine air flow spoilers were installed per phase on each circuit with an additional forty nine air flow spoilers on the OHSW on both circuits. The air flow spoilers on the conductors were installed using single conductor carts, while air flow spoilers on the OHSWs were installed by helicopter methods.
- The new conductor was pulled in using the existing conductor in the tension stringing process, suspended on the 180’ lattice towers to leverage gravity.
- Implosive connectors were used for joining conductors, rather than compression sleeves, which resulted in a faster installation time. The installation was performed using a bucket or crane.