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Mean time to repair (MTTR) is a basic measure of the maintainability of repairable items. It represents the average time required to repair a failed component or device. [ 1 ] Expressed mathematically, it is the total corrective maintenance time for failures divided by the total number of corrective maintenance actions for failures during a ...
Mean Time To Recover (MTTR) is the length of time required to restore operation to specification. This includes three values. Mean Time To Discover; Mean Time To Isolate; Mean Time To Repair; Mean Time To Discover is the length of time that transpires between when a failure occurs and the system users become aware of the failure.
Mean time to recovery (MTTR) [1] [2] [3] is the average time that a device will take to recover from any failure. Examples of such devices range from self-resetting fuses (where the MTTR would be very short, probably seconds), to whole systems which have to be repaired or replaced.
Availability is typically given as a percentage of the time a system is expected to be available, e.g., 99.999 percent ("five nines"). Serviceability or maintainability is the simplicity and speed with which a system can be repaired or maintained; if the time to repair a failed system increases, then availability will decrease. Serviceability ...
where MTTR is the mean time to repair. The MTTF of a system is the sum of MTTF S and MTTF D. To understand the relationship between MTTF S and MTTF D consider the case of a switch that turns a motor on or off. The switch has two failure modes: the switch can fail stuck closed or the switch can fail stuck open.
If we are using equipment which has a mean time to failure (MTTF) of 81.5 years and mean time to repair (MTTR) of 1 hour: MTTF in hours = 81.5 × 365 × 24 = 713940 (This is a reliability parameter and often has a high level of uncertainty!) Inherent availability (Ai) = 713940 / (713940+1) = 713940 / 713941 = 99.999860%
Greenwich Mean Time, the mean solar time at the Royal Observatory, Greenwich in England: often used to refer to Coordinated Universal Time; Local mean time, a form of solar time that corrects the variations of local apparent time; Washington Mean Time, the time at the meridian through the center of the old dome atop the main building at the old ...
A concept which is closely related to MTBF, and is important in the computations involving MTBF, is the mean down time (MDT). MDT can be defined as mean time which the system is down after the failure. Usually, MDT is considered different from MTTR (Mean Time To Repair); in particular, MDT usually includes organizational and logistical factors ...