In an automatic control system, where does the controller output signal go?

In an automatic control system, the controller output signal is directed to the final control element. The role of the final control element is to implement the necessary changes in the system to maintain the desired setpoint for the process variable. This could involve adjusting a valve position, changing a pump speed, or modulating a heating element, depending on the specific application.

The controller processes the error signal, which is the difference between the setpoint and the actual process variable, and generates an output that is sent to the final control element. This action ensures that the system responds appropriately to variations or disturbances, thus maintaining the desired operating conditions.

The other components listed in the options serve different purposes: the transmitter typically converts the output of the sensing element into a signal that can be interpreted by the controller, the sensing element measures the process variable, and the process variable itself is the parameter being controlled. The controller output specifically targets the final control element to enact changes, making this the correct position for the controller's signal.