Cascade control is defined as two controls working together, one an auto and one in Cascade.

• A. Two controls working together, one an auto and one in Cascade
• B. A single control with feedback
• C. Two independent controls
• D. A digital override system

Answer: (A)

Cascade control uses two control loops working in series: an outer loop regulates the slower variable and provides its output as the setpoint to an inner loop that rapidly drives the faster variable. Each loop has its own controller, and they operate automatically to improve disturbance rejection and speed of response. This arrangement—two controls cooperating, with one feeding the other in cascade—captures the essence of cascade control. The other descriptions describe a single feedback loop, two independent controls, or an override system, none of which describe the nested, cooperative setup that cascade control uses.