limitations of cascade control in case of reactors

limitations of cascade control in case of reactors

it requires an additional measurement (usually flow rate) to work. 

there is an additional controller that has to be tuned.

the control strategy is more complex – for engineers and operators

Cascade control is beneficial only if the dynamics of the inner loop are fast compared to those of the outer loop. Cascade control should generally not be used if the inner loop is not at least three times faster than the outer loop, because the improved performance may not justify the added complexity.