In industrial processes, temperature is often the most important variable to control. Temperature variations cause changes in flow, viscosity, pressure or humidity.
For accurate control of the process temperature without constant human operator involvement, all industrial thermal processes rely upon a temperature controller. The controller gets input from temperature sensors like thermocouples, RTDs or from a non-contact temperature sensor like an infrared temperature sensor. The temperature controller with its logic processes these inputs and sends an electrical signal to the power switch. The power switching device then adjust the power to the heating element.
Temperature controllers come in different versions. The first is a simple on/off switch. Once the temperature is achieved, the controller will turn on the full power independently if the temperature is 5 degree Fahrenheit to low or 50 degree Fahrenheit too low. This type of controller is adequate when the process temperature is not very critical and/or larger masses need to be heated.
The more common temperature controllers feature built in logic and can easily be configured to the process. These are often referred to as PID controllers (also known as Proportional Integral Derivative Controllers)
The controller attempts to correct the error between a measured process temperature and a desired set point by calculating and then outputting a corrective action (to power source) that can adjust the process accordingly. Optionally communication ports allow for easy connection to an Ethernet.
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