- a single loop is used with the SISO process without more than one disturbance/setpoint change demand or a upstream disturbance changing fast to the response time of the loop
- Feedforward is used as there is more than one disturbance or a disturbance changing fast to the response time of the loop, can have may feedforward loops integration
- Cascade is used as to eliminate the non-linearity of the valve; or when we can save expense for the control device (i.e., the control valve) and speed up the response of the whole system as two or more processes can use a same control device to control all of those process, this is often with level and flow control- one condition is the lowest/cascade/secondary process must have the response time 3-5 times faster the upper/master/primary process
Access this web sites: opticontrols.com see his blog with many interesting articles
or controlguru.com
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