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ITGlossary · UPS technology
MTTR (Mean Time To Repair)
The average time it takes to repair a system after a failure occurs.
Technical level:Intermediate
This time is measured from the moment a fault occurs until the system is back in normal operation. It includes diagnosis, the technician's arrival, sourcing the spare part and the repair itself, so in practice it can range from a few minutes to several days.
Together with MTBF it determines availability: the lower the MTTR, the less downtime. Modular UPS systems with hot-swappable modules, hot-swappable batteries and a maintenance bypass switch all reduce this time considerably.
For critical sites, check in advance how quickly a technician can respond, whether spare parts are available nearby, and whether staff know how to transfer the load to bypass safely.
Related terms
- AutonomyThe time a battery-powered system (like a UPS) can continue operating critical loads after a power failure.
- MTBFThe average operating time between failures of a device, used as a measure of its reliability.
- Auto RestartA UPS feature that automatically restarts the system after utility power returns following a shutdown.
- Capacity SystemParallel UPS units that share the load with no spare unit (N configuration), so the failure of one unit overloads the rest.
- Zero Transfer TimeA feature of online UPS systems, where the inverter feeds the load continuously so a power cut causes no gap at all.
- Offline (Standby) UPSA UPS that leaves the load on the mains and switches to battery only when the mains fails, with a short transfer time; the simplest and cheapest topology.