Why a MV/CV could get stuck at Setpoint Combine Status
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Products:
Aspen DMC3, Aspen DMC3 Builder
Last Updated:
06-Oct-2021
Last Updated:
06-Oct-2021
Versions:
Article ID:
000099042
Article ID:
000099042
Primary Subject:
Problem Statement
This solution frames some reasons behind and MV or CV variable stuck at Setpoint combine status and some ways to solve the problem
Solution
The combined status Setpoint can be achieved for and MV or CV when both the Low Limit and the High Limit are pinched at the same value. In this case, the controller will calculate a SS Target such that can maintain that condition, if enough MV are available and have a proper range to react.
However, there could be some scenarios where MVs or CVs can be stuck on setpoint even if the Limits are showing different values. So, we have these problems reported due to two causes:
1.- On V12 we have encountered that one MV or CV gets stuck on Setpoint, regardless of the controller is ON or OFF. This behavior may happen in both the controller deployed or in simulation on DMC3 Builder. This problem was addressed on Emergency Patch 3 for both Online Server components and DMC3 Builder Components. (VSTS
611026
). for V12.1 the problem has been addressed on Emergency Patch 1 for Online Server.
2.- MV/CV Model curves. By default, when an MV only has a model with one CV and the CV is Turn Off. This will put the MV in a situation where it does not have any related CV in service. When this happens the MV is pinched by the engine for safety reasons. This can be solved by either Turn Off the MV as it does not have anything to control or turn ON the CV if possible.
Keywords
DMC3, Setpoint, MV, CV