Frequently Asked Question
I would like to model a final element with the configuration of two 1oo2 interface modules and one 1oo1 final element, with specific manufacturer failure rates - how do I do this?
Last Updated 5 years ago
To model the redundant interface module you will need to define a user defined element that represents the 1oo2 configuration of the two interface modules.
You can then model the 1oo2 configuration in a separate SIF. If you set the mission time to the proof test interval and set the demand mode to high, the tool will calculate a PFH which is the equivalent dangerous undetected failure rate of your 1oo2 interface modules. Use this in the user defined device in the actual SIF. The calculated MTTFS can be used to determine the equivalent safe undetected failure rate (SU = 1/(MTTFS*8760)) The 8760 is to convert the MTTFS from years to hours as failure rates in exSILentia are specified in failures per hour.
You can then model the 1oo2 configuration in a separate SIF. If you set the mission time to the proof test interval and set the demand mode to high, the tool will calculate a PFH which is the equivalent dangerous undetected failure rate of your 1oo2 interface modules. Use this in the user defined device in the actual SIF. The calculated MTTFS can be used to determine the equivalent safe undetected failure rate (SU = 1/(MTTFS*8760)) The 8760 is to convert the MTTFS from years to hours as failure rates in exSILentia are specified in failures per hour.