Exam Question

### (a) Definition of Proportional Control Action (4 Marks)
Proportional control is a type of continuous or modulating control action where the controller's output is directly and linearly related to the magnitude of the error signal. The error is defined as the difference between the desired Set Point (SP) and the actual Measured Variable (MV) of the process.
Key characteristics are:
* **Direct Proportionality**: The size of the corrective action taken by the final control element (e.g., a valve) is directly proportional to the size of the deviation. A small error results in a small correction, while a large error results in a large correction.