[en] A 30-MJ (8.4 kWh) superconducting magnetic energy storage (SMES) unit with a 10-MW converter was installed during the later months of 1982 at the Bonneville Power Administration (BPA) Tacoma substation in Tacoma, Washington. The unit, which is capable of absorbing and releasing up to 10 MJ of energy at a frequency of 0.35 Hz, was designed to damp the dominant power swing mode of the Pacific AC Intertie. Extensive tests were performed with the unit during the first half of 1983. This paper will review the major components of the storage unit and describe the startup and steady state operating experience with the coil, dewar, refrigerator and converter. The unit has absorbed power up to a level of 11.8 Mw. Real power was modulated following a sinusoidal power demand with frequencies from 0.1 to 1.2 Hz and a power level up to +- 8.3 MW. The unit has performed in accordance with design expectations and no major problems have developed