What is the term for an uncontrolled oscillation of a controlled variable in automatic boiler controls?

The term for an uncontrolled oscillation of a controlled variable in automatic boiler controls is termed "hunting." This phenomenon occurs when the control system continuously overshoots and undershoots its set point, resulting in persistent oscillations around that point. Hunting typically arises when the feedback loop is too sensitive or there is a mismatch between the control system's response time and the dynamics of the system being controlled. As a result, instead of stabilizing at the desired level, the system continually oscillates due to the feedback mechanism reacting to changes. This behavior can lead to inefficient operation and can cause wear and tear on the mechanical components involved in the control system.

While pulsation, fluctuation, and vibration are relevant terms in different contexts related to system dynamics, they do not specifically refer to the controlled oscillation behavior characterized by hunting in automatic control systems. Pulsation often relates to periodic pressure changes, fluctuation may suggest more general variations, and vibration typically refers to oscillations in a physical structure, none of which capture the specific oscillatory feedback behavior associated with hunting in boiler control systems.