Rich mountain electric cooperative – crystal hill substation
Client: Rich Mountain Electric Cooperative
Location: Mena, AR
TOTH designed Crystal Hill Substation in 2014 for Rich Mountain Electric Cooperative in Mena, Arkansas. Crystal Hill is a 10 MVA distribution substation that serves mostly residential load through four 13.2 kV feeders. The substation is fed from a radial 69 kV transmission line that terminates on a box bay dead-end structure. A 69 kV gas circuit breaker provides protection and sectionalizing for the 69 kV transmission line. A second gas breaker isolates the transformer from potentially destructive currents. The 13.2 kV feeders are protected by vacuum circuit reclosers. The distribution structure features a transfer bus to allow for uninterrupted service while performing recloser maintenance. A pre-fabricated concrete control building houses digital protective relaying equipment, a 48 Vdc battery backup system, and auxiliary ac and dc load centers for the station. Structures and bus were designed for simplified utilization of a mobile substation during transformer maintenance and failure events.
Tasks performed include site selection, site layout, grading design, fence design, oil containment design, structural and foundation design, bus design, ground grid design, design of lightning protection, equipment specification, protective relaying application, relaying circuit design, auxiliary circuit design (ac and dc), dc load analysis and battery sizing, project management, construction observation.