A temperature controller is a device that’s particularly used for controlling the temperature. It measures the temperature (process variable) and then compares it with the desired value (set value). The difference obtained between these values is known as error. Temperature controllers use this error to decide how much heating or cooling is needed to bring the processed temperature back to the desired value. After the completion of this calculation, the controller will commence producing output signals that affect the overall change required. The output signal is known as the manipulated value that’s normally connected to a heater, valve, fan, or some other control element that is responsible for injecting or removing heat from the entire process.
The digital temperature controller manufacturer has designed this effective piece of instrument that takes input from a temperature sensor and has an output that’s usually connected to a control element either a fan or heater. For controlling the temperature without extensive operator involvement the temperature control system relies upon the controller which accepts a temperature sensor such as a thermocouple or RTS as an instrument. This way the actual temperature is compared to the desired control temperature and provides an output to a controlled element.
Different types of temperature controllers and their workings
There are three major types of temperature controllers including on/off, proportional, and PID. The operator can use one type or another for controlling the process.
On/off temperature control – this is the simplest form of the control device. There is no middle state, either the output from the device is on or off. The on/off control device switches the output where the energy can be turned on and off frequently. In certain cases, an alarm is used for controlling the process. This controller usually uses a latching relay, which can be set manually and is used to shut down a process whenever it has reached a certain point.
Proportional temperature control – This is designed for eliminating the cycle associated with on/off control. A proportional controller reduces the average power that’s supplied to the heater as the temperature starts approaching the set point. This slows down the effect of the heater so that it will not overshoot the setpoint, but it approaches the setpoint and maintains a stable temperature.
PID temperature controller – This type of temperature provides proportionally to integral and derivative control. This controller is combined with proportional control with two additional adjustments, which helps the unit to compensate for the changes in the system. These adjustments are usually expressed in time-based units and they are referred by their reciprocals including reset and rate. They are individually tested and tuned using either trial or error. It provides the most accurate control of the three controllers and is best used in systems with a relatively small mass which reacts quickly to changes throughout the process.
How do temperature controllers work?
To have an accurate process of temperature control without extensive involvement of the operator. There is an immense need to rely on a controller that accepts a sensor like a thermocouple or RTD. This way the actual temperature is compared to the desired temperature and provides an output to a control point.