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HP Forum Archive 05

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MTBF formulae?
Message #1 Posted by bill duncan on 10 Apr 2001, 1:29 a.m.

Does anyone remember what the (simplified) formulas are for series and parallel MTBF's are? Are they basically the same as the formulae for capacitors? [Adding MTBF's in parallel in redundant configurations, and 1/(1/a+1/b) ??]

I realize that it can get a whole lot more complicated than that when taking MTTR into consideration etc. But I just need something simple to get some approximations (which they all are anyway)...


Re: MTBF formulae? (some interesting references)
Message #2 Posted by bill duncan on 11 Apr 2001, 12:34 a.m.,
in response to message #1 by bill duncan

It would seem that I was being a bit too simplistic. I was trying to remember something I'd seen in the seventies.

I've found a few interesting references on the 'net which others may be interested in. Actually, the whole website these are from is very interesting. Does anyone have any other references to MTBF and availability math?

"Failure Rates, MTBFs, and All That",

"Infinite Parallel Redundancy",

Check out the entire website.

Not the same as the old mathworld site,, but very good reading.

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