To better understand the concept, consider a furnace whose temperature is to be maintained at 450°C. Using an On/Off controller, the burner initially turns on, and as the furnace temperature reaches 450°C, the gas valve is closed, turning off the burner. At this point, overshoot may occur, meaning the temperature may momentarily rise a few degrees above the set point, for example to 455°C. After the burner is off, the furnace temperature gradually decreases, and with a dead band of 10°C, the burner turns on again at 440°C, raising the temperature back to 450°C, and then turns off again. This cycle repeats continuously, keeping the furnace temperature between 440°C and 455°C.
It is important to note that in this type of control, the larger the dead band, the lower the system wear due to fewer on/off cycles, and the higher the system stability. This type of temperature control can also be implemented using temperature switch gauges, which, unlike digital controllers, do not require a control panel or power supply and can be used in harsh environments with high humidity, corrosive conditions, extreme seasonal temperatures, and more. NuovaFima, Italy, has recently introduced its new temperature switch gauge, the TCE model.
