The probability of satisfactory operation of a power system over the long run.
Relevant items: Stability Security
Reliability
Reliability of a power system refers to the probability of its satisfactory operation over the long run. It denotes the ability to supply adequate electric service on a nearly continuous basis, with few interruptions over an extended time period.
Reliability
NERC defines the reliability of the interconnected Bulk-Power System in terms of two basic and functional aspects, adequacy, and operating reliability.