EWA-NUI SUBSTATION
Oahu, Hawaii

OWNER—HAWAII ELECTRIC COMPANY
Honolulu, Hawaii

TriAxis performed the complete design of a four-line 138-kV ring bus switching station. The project included permitting, site civil, foundations, yard electrical, and relaying.

The station will initially be operated as a four-line position 138-kV ring bus. An 80 MVA 138/46-kV transformer feeds two 46-kV line positions and a 46-12.47-kV transformer with metal clad distribution breakers.

The 8-acre yard is designed to accommodate two future 138-kV lines with the 138-kV bus converting to a breaker-and-a-half scheme, three 80 MVA, 138-46 kV transformers feeding ten 46-kV line positions, two 50 MVA 138-25 kV transformers feeding ten 25-kV distribution lines, and three 12.5 MVA, forty-six 12.5-kV transformers feeding six 12.5-kV distribution lines.