Which type of continuous control maintains action when the signal is lost?

• A. Floating proportional control
• B. Feedback control
• C. Feedforward control
• D. Proportional control

Answer: (A)

Floating proportional control is designed to maintain action even when the input signal is lost. This type of control utilizes a mechanism that allows the controlled system to continue operating based on its last known state or on a predefined standby position. In scenarios where signals might become intermittent, such as in water treatment processes, maintaining some level of operation is critical.

In contrast, feedback control, while effective in stabilizing processes by adjusting based on the difference between the desired setpoint and the actual output, can falter when the signal it relies on is interrupted. Feedforward control anticipates disturbances and adjusts accordingly but also requires continuous input for effective operation. Proportional control responds directly to the input it receives, which can lead to a complete stop in action if that input is lost.

Thus, floating proportional control uniquely enables sustained operation in the absence of a signal, making it particularly beneficial in applications where consistency is vital.