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 & 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 & 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 & battery sizing, project management, and construction observation.