State the sequence that correctly represents the first three levels in the hierarchy of safety parameter limits.

State the sequence that correctly represents the first three levels in the hierarchy of safety parameter limits.

• A. Normal Automatic Controls -> Alarms / Operator Action -> Automatic Trips / Relief
• B. Normal Automatic Controls -> Automatic Trips / Relief -> Alarms / Operator Action
• C. Alarms / Operator Action -> Normal Automatic Controls -> Automatic Trips / Relief
• D. Design / Test Limit -> Break Point -> Emergency Operating Procedure / Operator Action

Answer: (A)

The first three levels follow a layered defense that protects the plant as conditions deviate from normal operation. Start with Normal Automatic Controls, which handle the process automatically during normal operation without human intervention. If a parameter drifts but isn’t yet unsafe, alarms alert operators and require action to bring things back in range. If the deviation continues or worsens, automatic protective actions kick in, such as trips or relief, to prevent reaching unsafe conditions. This sequence—Normal Automatic Controls, then Alarms / Operator Action, then Automatic Trips / Relief—captures how safeguards escalate from automatic control to operator involvement to automatic protection. Other sequences would imply alarms or automatic actions occur earlier or before stable automatic control, which isn’t how the protective layers are arranged.

The first three levels follow a layered defense that protects the plant as conditions deviate from normal operation. Start with Normal Automatic Controls, which handle the process automatically during normal operation without human intervention. If a parameter drifts but isn’t yet unsafe, alarms alert operators and require action to bring things back in range. If the deviation continues or worsens, automatic protective actions kick in, such as trips or relief, to prevent reaching unsafe conditions. This sequence—Normal Automatic Controls, then Alarms / Operator Action, then Automatic Trips / Relief—captures how safeguards escalate from automatic control to operator involvement to automatic protection. Other sequences would imply alarms or automatic actions occur earlier or before stable automatic control, which isn’t how the protective layers are arranged.