A project in PID temperature control and loop tuning

Automatic temperature control can be accomplished in different ways with varying degrees of accuracy. One method, PID control, normally requires a tuning process after the system is installed. This paper describes how a kiln with manual temperature control was modified to automate the process by utilizing a microprocessor-based PID controller. The controller accepts input from a "K" type thermocouple to switch the heater on and off with a solid state relay. The process variable is transmitted through a data acquisition system to a PC for storage and further analysis. This project provides valuable hands-on experience in control loop tuning and produces reasonably accurate results. The paper shows the design schematic and presents results.