Dormant failure

[radhi_ym]

i have a system "A" whose failure rate is 10 per million hour. Also i have a stand by system "B" whose failure rate is 5 per million hour.

since stand-by system needs to be checked for its serviceability(dormant failures), i check "B" system for 2 minutes only and switches off "B' system. Then i continue to operate system "A' only.
Also, at every 100 hours, i operate system B for one hour.how to find out overall reliability ?

problem may be complicated. could somebody help me out with equations please.

[Pantelis]

Yes it can get complicated. You can find some info/equations on standby systems at: http://www.weibull.com/SystemRelWeb/standby_components.htm

Now some questions:
a) You are assuming a constant failure rate (i.e. an exponential distribution) – which simplifies things quite a bit -- but is not necessarily a good assumption. Is the answer you are seeking going to be based on this assumption?
b) Now you say you “check” the system. What happens if the system is found failed during your check? Do you repair/restore it? If you do not -- the fact that you check it is then kind of irrelevant – other than accumulated operational time. If you do repair /restore it -- how long does that take?
c) Do you also check A when B is operating?

Now should you wish to do this yourself, software like BlockSim (http://blocksim.reliasoft.com/) can be utilized.