Substations

The Diamond Ridge Substation is a 115 kV main and transfer bus station with a 115 kV/ 69 subtransmission transformer and a 15 / 24.9 kVdistribution station transformer. The station serves as a critical switching station as well as a critical distribution source for the Homer area loads. The 115 kV main and transfer bus encompasses six breakers and utilizes SEL 487, SEL 311C and SEL-421 protective relays and an SEL-3354 for station automation. The distribution station includes 5 breakers and SEL-351S relays, SEL-487 relays and an SEL-3354 for station automation. The station was designed for extreme snow conditions that have been observed in the area. The project included extensive site work due to poor soil and permafrost conditions.

EPS completed the design and construction inspection for the new Retherford Substation in Anchorage. The substation consisted of two 100 MVA transformers, two 138 kV breaker and one-half bays and thirteen 34.5 kV breakers configured in a main and transfer bus scheme in metal-clad switchgear. EPS was responsible for the design of the substation civil work, bus layout, grounding and lighting. EPS was responsible for the design of the protective relay installation for the transmission lines, transformers and 34.5 kV feeders. EPS was responsible for the communications and SCADA interface with the Chugach control center. EPC completed the electrical testing and commissioning for the construction contractor. EPS completed the quality control inspection for the substation construction.

EPS completed the design and construction inspection for the new Postmark substation in Anchorage. The substation consisted of two 14 MVA transformers, two 138 kV breakers and nine 12.47 kV breakers configured in a main and transfer bus scheme with a double-ended bus arrangement in metal-clad switchgear. EPS was responsible for the design of the substation civil work, bus layout, grounding, and lighting. EPS was responsible for the switchgear specifications and protective relaying arrangement. EPS completed the quality control inspection for the substation construction.

EPS completed the design and construction inspection of the new Woodinville BP/Olympic station near Bothell, Washington. The substation consisted of four 4.16 kV feeders in metal-clad switchgear. The construction and commissioning of the substation was required to be completed within a single four day outage, and the design accommodated this restriction by pre-constructing a significant portion of the station prior to the outage.

EPS was responsible for the switchgear design and specifications, station layout and civil work, protective relaying settings, medium voltage and low voltage design, and arc flash calculations. EPS completed the quality control inspection, and all testing, commission, and startup for the substation construction.

EPS completed the civil, structural and electrical design for the 34.5 / 12.47 kV Airai Substation. Project included concrete block control building, relaying and control panels, four 12.47 kV breakers, installation of controls and modifications for one 34.5 kV breaker and three 34.5 kV motor-operated switches and SCADA control and monitoring for the station. EPS provided the structure design, electrical service, grounding, protective relaying and controls design. EPS completed the installation and commissioning.

EPS provided structural engineering to add a new bank to this existing substation. It included adding a new 230 kV, 400 MVA power transformer and new 230 kV deadend structures. Existing lattice steel deadend structures were analyzed for attaching the new bay, and steel procurement documents were developed for the new structure. The transformer foundation was designed for High Seismic Level in accordance with IEEE 693-2005.