The control challenge

We explained in the previous chapter how sensors play a vital role in sensing the actual conditions in the field. Many sensors are available to measure temperatures, such as resistance temperature detectors (RTDs), thermocouples, and thermistors. Many industrial applications deploy thermocouples and RTDs. RTDs are more precise and accurate. A typical setup can be viewed in the following figure:

Figure 2.1 – A typical setup to control temperature

If the heating area is greater, there could be several temperature sensors and an array of heating coils:

Figure 2.2 – Another typical setup for controlling temperature

The temperature controller could be a dedicated unit or part of the programmable logic controller (PLC). Both configurations are shown in Figure 2.3 and Figure 2.4:

Figure 2.3 – A setup where the PLC and the temperature controller are separate

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