What type of action increases branch pressure as the controlled variable increases?

The type of action that increases branch pressure as the controlled variable increases is characterized as direct acting. In a direct acting control system, when the controlled variable rises, the output of the controller also increases correspondingly. This means that as the measured parameter (like temperature or pressure) increases, the control element reacts by raising the output to manage that condition effectively. This is a fundamental principle in control systems where the goal is to maintain a specific setpoint by directly responding to changes in the system.

Typically, direct acting controls are implemented in systems where an increase in the process variable necessitates more flow, pressure, or similar, enhancing the output capabilities of the system. This alignment between input and output ensures that the control action is efficient for maintaining operational stability.

In contrast, inverse acting would result in a decrease in output as the controlled variable increases, which would not be effective in scenarios where an increase in a parameter needs to be countered by an increase in supply or response. Feedback action refers to systems where the output has a return influence on the operation, and proportional action relates to the relation of the controller output to the error, which may not directly correlate output increase to controlled variable increase without additional context.