Answer: C. Display.
Answer analysis: When discussing this question, we need to understand the role of each option based on the basic components of the automatic control system. Automatic control systems usually include several key parts to achieve automatic monitoring, adjustment and control of the system. Now, let's analyze these options one by one:
A. Measuring element and transmitter: This is an important part of the automatic control system, responsible for detecting the actual state of the controlled object (such as temperature, pressure, flow, etc.) and converting it into a signal that the controller can understand and process. This is the basis of the feedback control mechanism, so it is an essential part of the control system.
B. Controller: The controller is the "brain" in the automatic control system. It receives signals from measuring elements and transmitters, calculates control signals according to predetermined control strategies (such as PID control), and then sends them to the actuator. The controller is the core of the control system and is responsible for decision-making and adjustment.
C. Display: The display is mainly used to provide operators with information about the system status, such as the current temperature, pressure value or system operating status. Although the display plays an important role in human-computer interaction, it is not a necessary component for the control system to achieve automatic adjustment and control. It is more of an auxiliary tool to help operators monitor the operating status of the system.
D. Actuator: The actuator is responsible for receiving the control signal from the controller and converting it into physical action to achieve control of the controlled object. For example, in a temperature control system, the actuator may be a heating element or a cooling fan. The actuator is a key part of the control system to achieve its control objectives.
In summary, although the display is very useful for operators to monitor and understand the system status, it is not a necessary component for the automatic control system to achieve automatic adjustment and control. Therefore, what is not a component of the control system is C. Display.