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For an electronic device the the MTBF requirement is 4500 hours per year for 10 years, what does this MTBF mean and how to convert it into hours?

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    \$\begingroup\$ "hours per year" makes no sense here. If the client means he's operating the equipment 4500 hours per year and expects it to last (on average) 10 years, he may expect 45000 operating hours MTBF. Not 1.9 failures per year. Ask your sources to clarify the requirement. \$\endgroup\$ – Brian Drummond Sep 14 '17 at 9:34
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MTBF means mean time between failures, so on average every 4500 hours there is a failure. This is for the first 10 years. Since there are about 365.25 * 24 = 8766 hours per year, this means an average of 8766/4500 = 1.948 failures per year.

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  • \$\begingroup\$ @RoyC Thanks, you are correct (and adapted the answer). \$\endgroup\$ – Michel Keijzers Sep 14 '17 at 9:16
  • \$\begingroup\$ You from Germany? US English uses period comma instead of European (except UK) comma-comma. \$\endgroup\$ – winny Sep 14 '17 at 9:33
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    \$\begingroup\$ @Winny ... from the Netherlands, and fixed (I should have known). \$\endgroup\$ – Michel Keijzers Sep 14 '17 at 10:09
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The statement is rather ambiguous. I think it says what the MTBF is supposed to be after 10 years if you operate the device for 4500 hours per year. If so, that's a long-about way of saying the MTBF is supposed to be 45,000 hours. Perhaps this is supposed to give some indication of both elapsed time and running time. Some devices wear out due to time alone, but at a different rate when operated, so there is some sense to this.

MTBF means mean time between failures. If you get a large number of devices, then on average that is how long each runs without a failure. Conversely, if you get a large number of devices and run them for the MTBF period, half should have failed by the end of the test.

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