Features of substation in San Francisco

MISSION SUBSTATION, built by the Pacific Gas and Electric Company at Eighth and Mission Streets in downtown San Francisco, is a subtransmission station receiving power at 110 kv and distributing it at 12 kv. It will serve as a source of additional energy to increase capacity and relieve overloaded conditions in the downtown area. Within the building are two 35,000-kva 110/12-kv 3-phase forced oil-, forced air-cooled transformers; a 110-kv transmission ring bus with four 110-kv 800-ampere 5-cycle oil circuit breakers with an interrupting rating of 3,500,000 kva; one section of 12-kv subtransmission bus of the double-circuit-breaker type containing 15-kv, 1,200- and 3,000-ampere air-blast circuit breakers with an interrupting rating of 1,000,000 kva; reactors and cable terminal cells; three sections of 12-kv distribution bus of the main bus transfer bus arrangement containing 15-kv 1,200- and 2,000-ampere magnetic blow-out air circuit breakers with an interrupting rating of 500,000 kva; and thirteen 563-kva ±7 1/2 per cent step-type feeder regulators. Ultimately there will be two 35,000- and two 50,000-kva transformers, seven 110-kv oil circuit breakers in the ring bus, two sections of the 12-kv subtransmission bus, six sections of 12-kv distribution bus, and 24 feeders with step-type regulators. See Figure 1 for the general disposition of the electric equipment.