The New York Power Authority (NYPA) has asked New York state regulators for a declaratory ruling regarding work to be done on the Plattsburgh to Vermont Transmission Facility (PV20).
The project involves replacing 4,791 feet of submarine/subterranean 115-kV design capacity cables in New York with 230-kV design capacity cables. The cables to be replaced have reached the end of their useful life, NYPA added in its Sept. 13 petition filed with the state Public Service Commission (PSC).
NYPA requested that the PSC declare that the replacement of seven submarine/subterranean 115-kV cables in the state with four 230-kV cables within the 4,800 foot right-of-way (ROW) in New York is not subject to Article VII review.
Article VII review is not required because PV20 is not a “major utility transmission facility,” NYPA said, adding that only “major utility transmission facilities” require a certificate of environmental compatibility and public need.
Major electric transmission facilities include circuits with a design capacity of 125-kV or more and a length of one mile or more, or circuits with a design capacity between 100-kV and 125-kV and a length of 10 or more miles.
In this case, NYPA added, PV20 must continue to operate at 115-kV because the 7.5-mile aboveground transmission portion will remain a 115-kV circuit. The project will not render PV20 a major electric transmission facility because the design capacity of the nine-mile-long PV20 will remain 115-kV.
Furthermore, the installation of four 230-kV cables within 4,800 feet of ROW within New York does not render the project subject to Article VII review as a “major utility transmission facility” because the 230-kV cables do not meet the one-mile threshold for circuits with design capacities of 125 kV or more. The continuation of the cables into Vermont should not be considered in determining the length of the facility, NYPA said.
NYPA and Vermont Electric Power Company (VELCO) jointly own PV20, which is the only bulk power transmission intertie between New York and Vermont.
PV20 is an approximately 9-mile, 115-kV circuit that begins at the Plattsburgh substation in Beekmantown, N.Y., and ends at the Grand Isle transition station in Grand Isle, Vt.
A single 115-kV circuit extends 7.5 miles from the Plattsburgh substation to the Cumberland Head transition station predominantly on H-frame wooden poles. At the Cumberland Head transition station to the Grand Isle transition station, the single 115-kV circuit is comprised of seven submarine/subterranean cables for a distance of 1.7 miles, NYPA added.
The existing submarine/subterranean cables consist of four 115-kV cables that were installed in 1958 and three 115-kV cables that were installed in 1971. The original 1958 cables consist of one single cable per phase plus one spare. NYPA also noted that one of the 1958 installed cables failed in 1969 which required the installation of the three additional cables – one per phase – in 1971.
In August 2012, an assessment of PV20 determined multiple reasons why the existing submarine/subterranean cables from the Cumberland Head transition station to the Grand Isle transition station in Vermont require replacement to safeguard system reliability.
Thermal exceedances have damaged the cables, NYPA said. Also, the cables are at risk for failure due to age and an adverse operational environment: the cables are resting on rocks without proper support, there is silt build-up on the cables and armor corrosion. The 1958 cables have exceeded their projected 50-year useful life and the 1971 cables are approaching the end of their useful life.
Additionally, in the event of a malfunction, the cables could not be repaired because the original manufacturer no longer exists.
“Submarine/subterranean cables have a useful life of 50 years,” NYPA added. “Therefore, NYPA intends to install 230-kV design capacity cables in anticipation of future upgrades to the land based portion of PV20 expected within the next 20 years. Because the land portion of the PV20 is not part of the project and will remain at 115-kV design capacity, PV20 will remain a 115-kV circuit.”
NYPA has sufficient land rights at and near the existing Cumberland Head transition station to allow for the installation of the four 230-kV design capacity cables and it will negotiate with the New York State Office of General Services (OGS) for new ROW slightly north of NYPA’s existing ROW in Lake Champlain.
NYPA also noted that it will obtain all local, state and federal permits and approvals required for the project, including from the Army Corps of Engineers, the New York Department of State and OGS. VELCO has committed to obtaining all approvals and permits required within Vermont, NYPA added.