The Dequine Switch Station is an existing 345 kV breaker-and-a-half switchyard serving AEP’s Indiana Michigan Power division. ECI’s scope of work at this facility involved breaking two combined bus and line zones of protection into separated bus and line zones. This was accomplished by installing a 345 kV line terminal breaker between the line and the bus on each of the main buses in this yard. A bus differential relay scheme was also installed for each bus. In addition, reactive power improvements were also needed at this station. This was accomplished by installing 345 kV shunt bus reactors on each of the main buses. This work also involved adding a large number of relay panels inside the existing control building, as well as various upgrades to the AC station service network in the yard. A unique challenge to this station was utilizing 12/C cables for bushing current transformer (BCT) runs to alleviate voltage drop concerns on long BCT runs (often over 1,000 feet) in the large yard. Another challenge was working with “slide-in” relay panel steel, which allowed us to utilize existing panel spaces available in the control building.
ECI’s role for this station consisted of complete foundation, below grade, above grade, and P&C design packages. ECI also provided procurement support in the form of bill of material development. ECI also provided engineering support to the construction contractor to resolve any concerns that arose during construction.