What action does a two-position controller perform when comparing conditions to a set point?

A two-position controller operates by comparing the current conditions to a predetermined set point. Its primary function is to initiate a distinct response based on whether the current condition meets or deviates from this set point. When the conditions surpass or fall below the set point, the controller makes a clear decision to either start or stop the process being controlled. This is fundamentally different from maintaining a specific position or continuously adjusting the output.

The two-position controller is generally binary in nature, meaning it has two states (on/off), rather than gradually adjusting the control output. Thus, it is designed to switch the process on or off, ensuring that conditions align with the desired state quickly and effectively. This operation is essential in systems where binary control is sufficient, providing simplicity and reliability in maintaining the desired conditions.