Power City Substation Expansion

Location: Power City, OR


The Power City Substation is an existing distribution substation within UEC’s system that provides power to many members in Umatilla, Hermiston, and the surrounding areas. Originally built in 1999, the station has been providing reliable service for 23 years. Although still operating well, the needs and abilities of our system have changed over the years and we want to be proactive to stay ahead of future growth, which falls directly in line with UEC’s mission of providing reliable power to our members. By completing the Power City Substation High Side Expansion, our members can count on reliability and resiliency for many years to come.

Anticipated Construction Schedule

Start Date: September 2022

Completion Date: June 2023

Why Expand The Existing Substation?

UEC continues to invest in new infrastructure to meet the increased needs of the rapidly growing region. The expansion to the high side of the Power City Substation will aid in the continued, dependable electric service for nearly 900 members in the Umatilla and Hermiston areas. This project will allow for increased operational flexibility and heightened resiliency in the area and allow UEC to provide enhanced electrical service now and in the future.

The project will expand the high side of the existing substation to allow for 115kV (kilovolt) transmission lines to flow in and out of the substation, tying into UEC’s existing 115kV facilities in the area. The expansion consists of adding breakers and positions to the high side of the substation to accommodate the 115kV lines that will be coming into it.

What is the “High Side” of a Substation?

Substations within UEC’s system typically have two sides: a high side and a low side. Incoming transmission lines deliver power on a large scale from a generation location (such as the McNary Dam) to a substation serving a specific area within our service territory, or from one substation to another. The side where those transmission lines come in is referred to as the high side of the substation due to the higher voltage coming in. The low side of a substation has outgoing distribution lines that deliver power on a local scale to residences and businesses, called the low side because of the lower voltage. The transition from “high side” to “low side” takes place at the main power transformers within the substation, where the power is transformed from a higher transmission voltage to a lower distribution voltage.

How Will This Impact My Electric Service?

All load currently being served by the Power City Substation will be switched and served by a nearby substation as necessary during construction. There should be no noticeable impact to customers in terms of power service throughout the duration of the project.

Once this project is complete, the Power City Substation will be able to operate efficiently with other assets in our system, which will greatly improve flexibility and reliability to our members. The expansion will also allow UEC to better serve load growth for the entire Hermiston area in the future.