Large DC Magnet Power Supplies at SLAC

Currently a total of six dc magnet power supplies, ranging in size from 1.6 MW to 6.0 MW are in operation at the Stanford Linear Accelerator Center (SLAC). Five of these supplies are static converters, using step-down transformers and thyristors, while the sixth one is a two-unit motor-generator set. Certain design criteria have evolved, dictated by specific needs at SLAC and by operating experience obtained over the three-year period during which this equipment was installed. Primary power distribution is at 12.47 kV. Vacuum switches in place of circuit breakers incorporating special protective equipment to prevent complications have been successfully used to do the frequent switching required by the loads. Provisions have been made to permit reconnection of the output for use with the various loads. All static converters use oil-filled transformers, most of which are of special design. Twelve-pulse rectifier systems using SCR's are employed throughout, and are operated in such a way that in at least one case the inherently poor power factor of phase-controlled converters can be improved.