Circuit reliability

Circuit reliability (also time availability) ("CiR") is the percentage of time an electronic circuit was available for use in a specified period of scheduled availability. Circuit reliability is given by where "T" o is the circuit total outage time, "Ts" is the circuit total scheduled time, and "T" a is the circuit total available time. formula_1 
In addition, circuit reliability is the expected lifespan of operation of a functioning system under nominal conditions.