With UPS performance often not meeting expectations there is another alternative. Although UPS manufacturers and distributors quote MTBFs of more than 100,000 hours (8% chance of failure in 1st year, 92% availability of surviving 1 year without a fault and only a 37% chance of surviving 100,000 hours), truth is often that reliabilities with MTBFs of less than 60,000 hours (14% chance of failure and outage in 1st year), are often more the norm, an outage every five to six years on average is probably realistic. With guaranteed up times now days, a 10% chance of a power outage is just not tolerable. As we add in batteries, connections, generators, supply distribution and maintenance our overall system looks very vulnerable indeed. Schemes that provide redundant UPS configurations also flounder in their attempt to increase marginally above 200,000 hours. A far cry from the 1,500,000 hours that these configurations derive from theoretical calculation.
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