CyberCertPrepOT Security FundamentalsOT Fundamentals: Safety Systems & Physical SecurityEASYFree question
A furnace fuel solenoid is wired so that loss of power or loss of signal closes the fuel valve. Which design principle is this?
- A.Active redundancy with hot standby
- B.Fail-safe de-energize to trip design
- C.Diverse programming of two logic solvers
- D.Energize to trip design with battery backup
Why B is correct
De-energize to trip means the safe action occurs when energy or signal is lost, so wiring faults and power loss drive the plant safe. Energize to trip needs power to act and is used where loss of power would itself be hazardous.
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