Cascade And Selective Control Flashcards
Using cascade control, which controller can go into reset windup?
Primary and secondary
What term describes the primary control tracking the secondary set point?
Forceback
What mode is the secondary control in when the primary is in auto?
Secondary is in cascade.
Definition of cascade control
1 controller adjusting the SP of a second controller
What is the main reason for cascade control
To manage the disturbances in the manipulated variable.
How much faster does the secondary have to be then the primary to use cascade
Secondary must be 3x faster. You can have as many levels of cascade as you want as long as each one is 3x faster then the last.
Tune Primary or Secondary first?
Secondary. Work inside out
Is the secondary loop always positive or negative?
Always positive action
Which loop output goes directly to the FCE?
Secondary goes to FCE, Primary goes through Secondary
Determine the action of the controller if the valve is DA
Reverse acting controller on a direct acting valve.
What mode is the primary in if the secondary controller is in cascade.
Primary must be in auto or manual for secondary to be in cascade.
What is a common cascade control system
Controller with a valve positioner
What term best describes a valve positioner?
High gain P-only controller
What is the common mode for a controller in flow process
PI control
Non-linearity of the inner loop can be corrected by what?
Adaptive control
