A temperature sensor is an equipment that senses temperature changes. Industries are using temperature sensors for a number of applications nowadays. Most industrial applications include industrial machinery control, temperature measuring, process measurement, and manufacturing inspection and measurement. Temperature sensors are comprehensive that measure hotness or coolness and convert it into an understandable unit. At any point, you might wonder how the temperature of the huge concrete dams, furnaces are measured? Indeed, this is done with the help of specific temperature sensors. Every application has a unique temperature sensing requirement. These differences come from the object which we need to measure.
Types of Temperature Sensors
There are various Temperature Sensors available having different attributes relying on their actual application. They consist of two basic physical types. These types of contact and non-contact temperature sensors can be further subdivide. Contact temperature sensors include thermocouples and thermistors because they are in direct contact with the object to take the measurement. At the same time, the non-contact sensors measure the temperature by the thermal radiation released by the heat source.
Contact Temperature Sensor
Contact Temperature Sensor Types. These sensors are generally required to be in direct physical contact with the material being sensed and utilize conduction to measure changes in temperature. They are used to detect oils, solids, or gases above a wide temperature range.
Non-contact Temperature Sensor
These types of temperature sensors use convection and radiation to monitor temperature changes. We can use them to detect radiant energy as heat rises and cold settles to the bottom in convection currents or detect the radiant energy transmission from an object in the form of infrared radiation.
Commonly Used Temperature Sensors
Thermocouple
A Thermocouple uses an electrical sensor to detect temperature changes. The thermocouple is a combination of two materials and is attach at the end to form a junction. One end is the hot junction, and the other end of these dissimilar metals is a cold junction. Form different metals junction is at the last point of a thermocouple. Generally, thermocouple use in a broad spectrum of industrial and scientific applications. When this junction is heated, a voltage is produced that is directly proportional to the input temperature.
RTD Sensor
An RTD (Resistance Temperature Detector) is an infrared sensor whose resistance level changes as its temperature fluctuates. RTDs sensor works similar to thermistors and measures ohmic resistance to measure temperature. To calculate the resistance across an RTD sensor, apply a constant current to measure the resulting voltage and determine the RTD resistance. RTDs exhibit fairly linear resistance to temperature curves over their operating regions, and any nonlinearity is highly predictable and repeatable. The RTD sensor is bias using a steady current source. To lessen self-heat due to power emission, the current magnitude is moderately low.
Thermistors
Thermistors are an interesting piece of electrical engineering, which in many ways makes them a unique sub-class of device. It works on the same principles as electronic thermometers (also known as digital thermometers), where we use the temperature sensor for measurement. Digital thermometers, unlike traditional thermometers, do not require any temperature reference material to measure a temperature. With these thermometers, a change in temperature tells the user that something is amiss regarding temperature. Thermistors differ from digital thermometers in that they need a temperature reference material in order to work, and these references can be either conductors or sensors.
Thermistors can also measure temperatures in a different way compared to electronics thermometers; instead of changing focus from one temperature range to another, they tend to work within a single temperature range, often times the entire range of a wide variety of temperatures. This means that they are more accurate than other types of thermometers, which allows them to provide a highly consistent measurement of temperatures.
Semiconductor Sensor
Recently, semiconductor temperature sensors have developed into a class of their own when combined with other advanced temperature monitoring devices. Using These sensors in many different applications and they are very innovative devices. These sensors provide accurate temperature readings that are quick to take and give a true picture of the interior temperature of any area in a large building or a room in a home. They can get integrate with other types of advanced monitoring devices to provide even more information about the environment.
Semiconductor-based temperature sensors typically are based on discrete ICs that provide high accuracy and high bandwidth over a wide temperature range (-, 55 C to + 150 C). Because these are discrete ICs, They can easily contain an elaborate signal processing circuit inside the package. Thus monitoring numerous high-temperature and pressure points.
What To Consider While Selecting a Temperature Sensor
While selecting a temperature sensor for use in your application, you have to look up many aspects, including temperature range, accuracy, stability, or size. Different temperature sensors can measure different ranges and might be more accurate over a specific range. Ensure you check the range of the temperature sensor and the expected range of your application. The range of the temperature sensor should be available on the sensor datasheet. Accuracy is another important consideration for any application. Generally, thermistor probes are the most accurate temperature sensor.
