South Cummings 69KV-12kV Substation Upgrade, Naval Base San Diego:

The project scope was the reconfiguration and expansion of the South Cummings Substation at Naval Base San Diego to meet the growing electrical demand. The project included reconfiguration of the two SDGE interconnections, each with single circuit breakers to a six-element 2000-amp rigid bus in a ring configuration using 72kV class SF6 filled circuit breakers with two positions for existing SDGE services, two positions to feed existing transformers, and two positions for the addition of two 40/50/60 MVA 69-12kV transformers with ALTC. Secondaries of each new transformer were connected to a reactor in parallel with a Current Limiting Protector (CLiP) to limit the flow of fault currents to levels acceptable for existing equipment downstream of the substation. 3OOOA 15 kV bus duct connected to a 15kV indoor type switchgear in “Main-tier-Main” split bus configuration, with a total of 10 feeder breakers and underground outgoing feeders on both sides. EPI’s design included the rearrangement of toads between new and existing portions of the substation and the upgrade of select circuit breakers in the existing switchgear. Project responsibility also included coordination of the design elements including protection and system coordination to meet aft Interconnection Agreement requirements between the Navy and SDG&E. The design of the substation included a fully integrated SCADA system that can be monitored and controlled remotely via fiber optic connections. The 69KV side control and protective relays are in an integrated control panel inside the switchgear building. API feeder, bus, and transformer protection use SEL relays.

The newly upgraded substation can carry the anticipated load through 2030. EPI performed all studies including toad forecasts, the 100% of the design, assisted clients through the bidding process, and performed aft construction-related engineering services through the completion of the project.