command disagree
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When the O*dizer Steam Valve Timer expires and the Steam (O*dizer) bypass valve, XV 1111, is NOT confirmed open (command disagreement for XV-1111), set the Total Steam Flow controller, FC-1000, mode to AUTO. Command disagreement for XV-1111? This post was last edited by echommm on 2008-2-25 08:51]
The XV-1111 instruction is prohibited, or there is a conflict in the instructions
Sometimes, due to the control system or actuators not functioning properly, other issues may arise. In my opinion, “command disagree for XV-1111” should be translated as: XV-1111 is unable to execute operation commands.
The command does not match for XV-1111: The actual status of XV-1111 is inconsistent with the command.
Open the Steam bypass valve, XV-1111. • When it is confirmed that the Steam bypass valve, XV-1111, is open and the Steam Valve Timer has not expired, set the Total Steam Flow controller, FC-1000, to LOCAL OVERRIDE with an output of 0%. When the Steam Valve Timer expires and the Steam bypass valve, XV-1111, is not confirmed to be open (the commands for XV-1111 do not match), set the mode of the Total Steam Flow controller, FC-1000, to AUTO. It is stated earlier to “open the steam bypass valve XV-1111”, but later it says “when the steam valve timer expires and the steam bypass valve XV-1111 is not confirmed to be open”. Does this mean that “for XV-1111, the commands are inconsistent”? This post was last edited by echommm on 2008-2-23 21:08]
Open the Steam bypass valve, XV-1111. • When it is confirmed that the Steam bypass valve XV-1111 is open and the Steam Valve Timer has not expired, set the Total Steam Flow controller, FC-1000, to LOCAL OVERRIDE with an output of 0%. When the Steam bypass valve XV-1111 is confirmed to be open and the Steam Valve Timer has not run out, the output of the Total Steam Flow controller FC-1000 will be set to 0%. When the Steam Valve Timer expires and it is confirmed that the Steam bypass valve XV-1111 is not open (the command for XV-1111 does not match the actual status), set the mode of the Total Steam Flow controller FC-1000 to AUTO. In this case, since the Steam Valve Timer has expired and the Steam bypass valve XV-1111 is not open (the command differs from the actual status), the operator needs to set the controller to the AUTO mode via the DCS; generally, control valves on a DCS can be set to either AUTO or CAS mode – AUTO mode allows manual adjustment, while CAS mode operates under interlocks. Those with experience in DCS operation should understand what this means. In the first scenario, the main steam valve is in CAS mode; if the bypass valve is opened, the main valve will automatically adjust to 0% within the specified time. If the bypass valve should be open but isn’t, and the time limit has passed, the operator must manually set the main valve to the AUTO mode in order to adjust its opening degree and allow steam to flow into the system.
This is similar to matrix management; if two command sources issue conflicting instructions, safety comes first, and methods such as delays can be used to reverify these commands, with appropriate criteria for making decisions. This requires comprehensive judgment from personnel involved in design, operation, debugging, etc. FYI
When the steam valve timer runs out and the steam bypass valve XV-1111 is not confirmed to be open (inconsistent with the command for XV-1111): handshake :handshake :handshake