Magnet power supply reliability at the Advanced Photon Source

Operational goals for the Advanced Photon Source facility include 95% user availability and a mean time between unscheduled beam losses of 30 hours, with 5,000 user hours of scheduled beam per year. To meet these goals, operational goals for the magnet power supply system have been set at 99% availability, with a mean time between faults of 200 hours. The large number of power converters (1,400 in the storage ring alone), complexity of the overall systems, and limited machine shutdown time make meeting these goals particularly challenging. During fiscal year 2000, power supply system availability was close to 99%, but the mean time between faults was only 85 hours. Efforts are ongoing to incrementally improve power supply reliability and to meet the operational goals. This paper presents important power supply operational statistics and describes our approach to meeting the reliability goals