MTBF Question

[delb]

Hi.
I am new to this and have to work out a systems reliability that has 4 components all in parallel. The MTBF's I have calculated for each system using the failure rates and MTBF's. These are A = 1433 hours, B = 1443 hours, C =1342 hours and D = 1232 hours. To calculate the systems overall MTBF I have converted these to failure rates and multiplied them ie A x B x C x D. giving me 2.92499E-13. I have then done
1 / 2.92499E-13 giving me a MTBF of the system of 4.25455E+12 hours. Is this correct as it seems very high.

Many thanks

 

[IRstuff]

What exactly do you mean by they're all in parallel"? Are they fully redundant? If so, why do they have differing MTBFs?

see:

http://www.pixelbeat.org/docs/reliability_calculator/

and:

http://www.ece.cmu.edu/~koopman/des_s99/traditional_reliability/#Parallel Reliability

TTFN

FAQ731-376

 

[delb]

Hi IRStuff.

Thanks for that, they are fully redundant but have different MTBF's as the each system is composed of different parts although do the same thing, should one go down.

Cheers