Seeking help with cascade control problems
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We have some issues with our cascade control systems and need everyone’s help. First, there are two cascade controls; after the outer-loop cascade is activated, the MV value does not change in response to changes in the PV value, remaining at a constant level. The outer ring represents temperature, while the inner ring represents flow rate. After incorporating the cascade control, whether the temperature rises or falls. The outer loop MV value remains constant, which causes the inner loop SV value to remain unchanged as well. Cannot be adjusted. Second, there is a cascade control system: the outer loop functions normally, but the MV value of the inner loop does not reach 0 when the SV value does. Is this related to the fact that flow stops when the valve opening is still at around 10%? I appreciate your help. Thank you
Pay attention to cascade control; I haven’t done it myself, I need to learn it*
It sounds like auto-pitching wasn’t used? Is there still no PV value tracking?
The mode must be incorrect; one is the CAS cascade mode, and the other is the AUT automatic mode.
I’m not sure whether it’s the problem described by the original poster or my understanding is incorrect. MV is a manual output; when the regulator is in the manual position, it does not change on its own (it tracks the automatic output SV in automatic mode). So in question one, if the cascade is disconnected but the main controller is set to manual, the aforementioned situation occurs. In Question 2, if the auxiliary regulator is in manual mode, the MV will not change either as a result of changes in SV. However, regarding the description in question two here, it seems that the auxiliary regulator is not in manual mode.