Subsystems can be configured by clicking on the required Hazard -> SIL Verification -> RBD Analysis.
Subsystems (i.e. Sensors, Logic Solvers and Final Elements) can be configured based on the SIF configuration by carrying out the following steps:
Note: Subsystems that do not have Elements configured within those subsystems will be disabled, and will appear greyed out (ie. “Add Sensor Branch” menu option is disabled if there are no Sensor Elements configured).
An overview of the subsystems will be presented showing the contribution of each subsystem towards the overall PFD / PFH.
Adding a Branch
When adding a Branch you most provide the following information:
- Voting (MooN) – The voting configuration of the devices. The voting configuration is unrestricted, however only voting configurations with up to 4 channels (N <= 4 – i.e. 1oo2, 1oo3, 2oo3, 1oo4, 2oo4 and 3oo4) can be configured with independent channels (i.e. different Elements in each channel)
- Channel – The number of Channels displayed is dependent on the Voting configuration. Where M is not equal to N you can configure multiple devices in each Channel in series
When configuring a Channel provide:
- Device Tag – The Elements for the selected subsystem will appear in the dropdown list
- Dangerous Failure Mode – Select the appropriate Dangerous Failure Mode for Devices with multiple DFMs
A live view of the Reliability Block Diagram (RBD) is shown as it is being created.
The overview shows the Results of the SIL Verification, including
- Selected PFD Target – The PFD Target from the SIL Determination
- PFD Achieved – The total PFD calculated by adding the PFD of each subsystem
- Selected SIL Target – The SIL Target from the SIL Determination
- SIL Achieved (Architecture) – The SIL Achieved based on the architectural requirements of the subsystems. This is calculated to be the minimum Architectural SIL of the subsystems
- Result – Presents the results of the analysis. A green tick denotes the SIF meets both PFD and Architectural targets. A red cross denotes that either the PFD Target, SIL Target or both are not met
- Status – The status of the of the SIF from the SIL Determination
Note: If the SIL Determination has been carried out in Continuous Demand mode, then PFH Target and PFH Achieved are used with the units of per hour.