CyberCertPrepOT Security FundamentalsOT Fundamentals: Safety Systems & Physical SecurityMEDIUMFree question
A LOPA team wants to credit an alarm plus operator response as an independent protection layer against tank overfill. Which condition must hold before credit is allowed?
- A.The alarm is configured with the highest priority on the BPCS display
- B.The detection path is independent of the loop that caused the demand
- C.The alarm setpoint equals the control loop setpoint in the BPCS
- D.The alarm reads the same transmitter that feeds the control loop
Why B is correct
An independent protection layer must not share a failure cause with the initiating event. If the alarm uses the control loop transmitter then one sensor fault both creates the demand and hides it. Priority or setpoint choices do not create independence.
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