EHV POWER HAS PROJECTS ACROSS
NORTH, CENTRAL AND SOUTH AMERICA.
EHV Power has a long record of delivering high voltage underground transmission cable system projects successfully – safely, on time and on budget. We work collaboratively with clients to meet their needs with a quality, cost-effective solution. Our electrical transmission projects have taken our highly experienced and mobile work crews across Canada, the United States and into parts of Central and South America.
Central / South America
EHV Power has a long record of delivering high voltage underground transmission cable system projects successfully – safely and on time. A section of two 230kV high-pressure ﬂuid ﬁlled (HPFF) cable circuits route crosses through the future Light Rail Transit in the City of Ottawa. To accommodate the future rail system, the HPFF cables were required to be relocated. To decrease the project costs, EHV Power worked with the City and the utility on reducing the amount of the relocated section.
A custom designed joint bay was built to accommodate the new and current high-pressure steel pipes. The utility’s approved cable joints were supplied by our parent company, USi, and registered with the provincial standards authority.
Effective coordination and logistics with the liquid nitrogen supplier were fundamental to maintain a freeze plug on the pipes during the cable splicing works. Despite a major fire at the electrical substation causing a 6-month project delay, the circuits were successfully relocated and placed back into service before year’s end – in time for the construction of the rail transit system.
In Lake Ontario, Canada, on Amherst Island, 26 wind turbines produce 75 Megawatts (MW) of generating capacity. A 3 phase 115kV submarine cable interconnects the wind farm on the island to the electrical grid. EHV Power was contracted to install the submarine anchor clamp and cable terminations on riser poles.
EHV Power worked with the Owner’s Engineer to simplify the installation process for both the anchor clamp and cable terminations. Additionally, as an approved electrical contractor with the Electrical Safety Authority, EHV worked with the Authority to add safety measures to the riser poles for safe operation of the submarine cable circuit.
The works were performed during a cold Canadian winter. Enclosed heated scaffolding was erected on Amherst Island and on the mainland for the cable termination works. The submarine cable was unwound and trained onto the riser poles. The 115kV cable terminations were assembled and supervised by the manufacturer’s inspector. A successful AC HiPot test with PD measurements was achieved.
On November 3, 2008, a fire hit the surface of a cable shaft at the Churchill Falls 5,428 MW hydroelectric facility in Labrador, Canada. The fire damaged the 245 kV power cables connecting the underground transformers to transformers on the surface. Two of the 11 generating units at the facility became inoperable. This resulted in a reduction in generating capacity available. At the request of the owner of the facility, EHV Power’s personnel flew to the facility on the evening of the fire to assess the damage. RGP (Residual Gas Pressure) analysis on the spare LPOF (Low Pressure Oil Filled) cable reels commenced the next day. A day-by-day project schedule was prepared to remove the damaged cables from the tunnel and shaft. Installation of new cables began immediately after the removal. One of the two disabled generators returned to service just two and half months after the fire. Repairs to allow the second unit to return to service occurred in the summer of 2009 upon the arrival of new underground high voltage cable materials.
Forty-year-old oil-impregnated 138 kV power cables were replaced with solid dielectric XLPE cables in Calgary, Alberta. This two-year project included removing both the two circuits SCFF and two circuits HPFF cable system. The entire length of each circuit’s dielectric fluid were drain, collected and properly disposed. The underground high voltage cable, cable pipe, pothead risers, pothead termination foundations were removed. Also included in the scope of work was the disposal of contaminated soil and the installation of steel pipes underneath the railway and LRT tracks.
The new XLPE cables were installed in a new encased concrete ductbank with 16 manholes in the downtown core. Asbestos was discovered on the HPFF pipe and proper asbestos abatement procedures were implemented. Despite this setback and even obliging the city’s 10-day major festival (Calgary Festival), the project schedule was still maintained within two weeks of the original in-service date. A complete restoration was performed along the city’s sidewalks and streets on the utility’s right-of-way. At the substation, a Distributed Temperature Sensing (DTS) system was installed to monitor the newly installed circuits.