ABSTRACT
Power outages disrupt more businesses than any other factor (see Figure 9.1). I lose two hours of work on the computer; Jane Doe gets stuck in an elevator; Intel loses a million dollars worth of computer chips; a refinery flames out, stopping production and spewing pollution into the air. End users expect good reliability, and expectations keep rising. Interruptions and voltage sags cause most disruptions. In this chapter we study “sustained” interruptions, long-duration interruptions generally defined as lasting longer than 1 to 5 min. We investigate momentary interruptions and voltage sags in the next chapter. Reliability statistics, based on long-duration interruptions, are the primary benchmark used by utilities and regulators to identify service quality. Faults on the distribution system cause most longduration interruptions; a fuse, breaker, recloser, or sectionalizer locks out the faulted section.
