ABSTRACT
A process control loop can best be understood when its components are combined in a loop and studied in operation. This chapter describes how both simulated processes and real processes can be constructed. The axiom in plane geometry that "two things equal to the same thing are equal to each other" applies to the technique of simulating a process and its control. The axiom is applied by constructing a system, a simulator, which simulates the behavior of the physical system under study. The Foxboro Company electronic process simulator is a lightweight, portable, self-contained real-time simulator. A wide range of industrial processes can be simulated with this device. An open-loop step upset can be simulated by switching the controller to manual control. Using this technique, and the faster time base, the step upset or signature curve of the simulated process can be adjusted to correspond to the process under investigation.
