Temperature control is a process in which change of temperature of a space (and objects collectively there within) is measured or otherwise detected, and the passage of heat energy into or out of the space is adjusted to achieve a desired average temperature. An object’s or space’s temperature increases when heat energy moves into it,
Why do we need temperature controllers?
Temperature controllers are needed in any situation requiring a given temperature be kept stable. This can be in a situation where an object is required to be heated, cooled or both and to remain at the target temperature (set point), regardless of the changing environment around it. There are two fundamental types of temperature control; open loop and closed loop control. Open loop is the most basic form and applies continuous heating/cooling with no regard for the actual temperature output. It is analogous to the internal heating system in a car. On a cold day, you may need to turn the heat on to full to warm the car to 75°. However, during warmer weather, the same setting would leave the inside of the car much warmer than the desired 75°.
Closed loop control is far more sophisticated than open loop. In a closed loop application, the output temperature is constantly measured and adjusted to maintain a constant output at the desired temperature. Closed loop control is always conscious of the output signal and will feed this back into the control process. Closed loop control is analogous to a car with internal climate control. If you set the car temperature to 75°, the climate control will automatically adjust the heating (during cold days) or cooling (during warm days) as required to maintain the target temperature of 75°.
Introduction to Temperature Controllers
A temperature controller is a device used to hold the desired temperature at a specified value.
The simplest example of a temperature controller is a common thermostat found in homes. For instance, a hot water heater uses a thermostat to control the temperature of the water and maintain it at a certain commanded temperature. Temperature controllers are also used in ovens. When a temperature is set for an oven, a controller monitors the actual temperature inside of the oven. If it falls below the set temperature, it sends a signal to activate the heater to raise the temperature back to the set point. Thermostats are also used in refrigerators. So if the temperature gets too high, a controller initiates an action to bring the temperature down.
Temperature controllers in industry work much the same way they do in common household applications. A basic temperature controller provides control of industrial or laboratory heating and cooling processes. In a typical application, sensors measure the actual temperature. This sensed temperature is constantly compared to a user set point. When the actual temperature deviates from the set point, the controller generates an output signal to activate other temperature regulating devices such as heating elements or refrigeration components to bring the temperature back to the set point.
- Suitable for remote application
- Low cost due to wafer level trimming
- Operates from 4 v to 30 v
- Less than 60 –uA current drain
- Low self heating 0.08 ‘c in still air
- Low impedance output
- 0.5 ‘c ensured accuracy (at 25 ‘c)
- Rated for full -55 ‘c to 150 ‘c range