Case Study

Distribution Addition & RTU Replacement

Client challenge:

Our client, is a leading sustainable energy company with $38 billion in assets and operations in 24 U.S. states. To improve reliability, our client required upgrades to a substation. This required expanding the existing Substation to accommodate the addition of a new 19.9kV distribution circuit, including recloser, grounding banks and voltage regulators. As part of this upgrade, there was a requirement to replace the existing legacy RTU, new yard expansion, new yard access, 34.5kV bus expansion and existing 34.5kV capacitor bank relocation.

How we helped:

SGC Engineering was commissioned to complete the upgrades which included a new radial distribution circuit to source a stepdown transformer 7.2 miles from the existing station, while also creating terminals that allow installation of a mobile transformer. The project scope was established to facilitate future upgrades as part of a wider area long term program, that met the local near-term needs for distribution level customer reliability.

In addition, the existing facility included the need for an RTU replacement due to the retirement of a legacy RTU that could not be expanded or modified to accommodate the new control, status and indication from the new distribution circuit. The old RTU was replaced with a new RTU cabinet with a modern solution that allowed the cutover of existing cabling to provide a one-for-one replacement, without impacting all other protection and control systems at the facility (which were not otherwise part of the project). The relocation of the existing 5.4MVAR capacitor bank and yard expansion was to facilitate the need for a mobile location for reliability concerns.

Our team was responsible for all survey, civil, substation electrical, protection and control, integration, relay settings design and testing and commissioning, as well as Owner’s Engineering services. These included all design aspects, Geotech, substation studies, equipment specifications, outage coordination, cutover planning and protection coordination studies.


The project was completed with no notable issues. All work was completed on time and on budget without putting additional burden on the client and client resources. The project was a direct award and not competitively bid, therefore the work was appropriately estimated and demonstrated SGC’s value sales ability.

An added benefit was the RTU design that included replicability and repeatability for replacements of legacy RTU upgrades of similar facilities in the future. The design was established with the intent to be used for a one-size-fits-all approach for client needs with their aging infrastructure that is no longer supported.

12kV ground bank

Construction of the Substation upgrades