Energy :: Traditional
7th Avenue Substation 115-kV Rebuild
Longview, WA
DEA (formerly TriAxis, a Division of David Evans and Associates) provided design services for the reconstruction of a complex distribution substation. Fed from three high-side line positions, the substation received a new 20/26.7/33.3 MVA, 115‑13.09/7.56 kV three-phase, two-winding power transformer with LTC. The existing substation was torn down and the new substation was constructed on the same site.
Design features included:
- A 115-kV primary aluminum bus, surge arresters, a circuit switcher for over-current protection, power-circuit breakers, and provisions to serve a future second transformer
- Complete design of oil retention system for the power transformer.
- Foundation design of all high-side equipment (pull-offs, circuit breakers, switch stands, VT stands, bus supports, and circuit switcher), including anchor bolt calculations.
- Dimensioned steel support concepts and loading requirements.
- The existing ground grid was analyzed using CDEGS software to verify safe touch-and-step potentials inside and adjacent to the substation.
- Design of all substation feeder getaways, including conduits, junction boxes, pull vaults, and equipment connections.
- Fence design using a combination of concrete wall and chain-link, along with perimeter curbs, gates, and signs.
- The 13.09-kV, 1200-amp bus design with 500-MVA-rated breakers consisting of rigid aluminum tubing, and aluminum and copper jumpers.