Cascade control involves using two or more control loops, with one controller acting as the primary/outer loop that sets the setpoint for the secondary/inner loop controller. This cascade structure allows the overall control to respond faster to disturbances and provide more consistent performance compared to a single control loop. However, it requires an additional measurement and controller that adds complexity.

2. Applications with two or more capacities (such as heated
jackets) are inherently difficult to control with a single control
loop due to large overshoots and unacceptable lags. The
solution is a cascade of two or more control loops, each with
its own input, in series forming a single regulating device.
Cascade control indicates two closed loop control cascaded to
each other. In this control a process is controlled by two
controllers in such way that both are acting for each other.
The controller driving the set point is called the primary,
outer, or master controller. The controller receiving the set
point is called the secondary, inner or slave controller.

3. 1) Responding faster to certain disturbances
2) Providing more consistent performance over a range of
process conditions
1) It requires an additional measurement (usually flow rate) to work.
2) There is an additional controller that has to be tuned.
3) The control strategy is more complex.

4. CONTROLLED
MANIPULATED

5. primary
secondary