Reliability is most often expressed as the frequency of interruptions and expected number of hours of interruptions during one year of system operation. A reliability index is the probability that a device will function without failure over a specified time period. This probability is determined by equipment maintenance requirements and failure rates. Using probability and statistical analyses, the reliability of a power system can be studied in depth with digital computer programs. When comparing various industrial power system design alternatives, acceptable system performance quality factors (including reliability) and cost are essential in selecting an optimum design. Momentary and sustained system interruptions, component failures, and outage rates are used in some reliability programs to compute overall system reliability indexes at any node in the system, and to investigate sensitivity of these indexes to parameter changes. With these results, economics and reliability can be considered to select the optimum power system design. This course was designed for both engineers in disciplines other than electrical, and electrical engineers who desire to deepen their understanding of reliability assessment. This course is adapted to the practical world of industrial and commercial electrical systems. Learning Objectives

• Definitions of the most important electrical system reliability indexes
• Key electrical system reliability definitions
• Data needed for system reliability evaluations
• Variables affecting reliability indices
• Method for improving overall electrical system reliability
• System automated actions for improving reliability
• Electrical system reliability evaluation methods
• Service restoration principles