What is Cascade Control?

Cascade management concerns the process management strategy in which the procedural variable is controlled by manipulation of the desired value of the related process variable. In this particular strategy, the variable interest is managed by two control loops working in the tandem. In the chemical processes industry, a cascade control system is often used to reduce the effects of disorders and disturbance on the primary control goal. These loops can also be referred to as an outer loop and an inner loop. The primary loop provides a secondary loop for a desired value or goal for the process related to the primary procedure. The primary loop is sometimes known as the main loop because it provides the desired value that must be followed by a secondary loop or slave loop. To function effectively, the dynamics of the secondary loop process must be much faster than the primary loop dynamics. In general, the dynamics of the secondary loop process must be at least four times fastmore than the dynamics of the primary loop process.

The most common application of cascading checks for most chemical processes involves using the flow controller as a secondary loop. Most flow drivers have a very fast response time, making it suitable for secondary loops. The primary loops tend to focus on variables such as temperature, levels, hydrogen hydrogen levels or chemical composition.

Cascade Control is not necessarily limited to systems based on only two control loops. More cascading arrangements work in the same way as the traditional cascade loop, alems more than two loops. For example, the chemical composition analyzer and a long dead loop can rely on a loop for temperature control to remove the process disturbance. The temperature control loop can then rely on an even faster control, such as the flow control.

existsSeveral factors that are relevant in the development of cascading regulators for the process. For example, a control engineer would have to consider whether the chosen secondary loop had a strong effect on the primary loop of interest. The engineer would also need to know the dynamics of the process of the proposed secondary loop. Such factors could determine whether the proposed secondary loop is able to absorb the disturbance of the process and prevent them from affecting the primary loop.