How is the transducer used to measure temperature

Temperature converter

Definition: The temperature converter converts the heat energy into a physical quantity such as displacement, pressure and electrical signal, etc. It is an electrical device for automatic temperature measurement. The main principle of the temperature transducer is to measure the heat and, once converted, to translate the information into readable form.

The following is the characteristic of the temperature converter.

  1. The input is always a thermal quantity.
  2. The converter usually converts the amount of heat into an alternating quantity.
  3. It is used to measure the temperature and the heat flow of the devices.

Sensor element

The sensor element used in the temperature transducer must have the properties to change the properties with the change in temperature. Examples - The platinum metal is used as a measuring element in the resistance thermometer.

  1. The temperature measuring element converts the temperature into heat.
  2. The temperature change with respect to the resistance should be large.
  3. The measuring element must have a high resistance.

Types of temperature sensors

The temperature converter is mainly classified into two types.

Contact temperature sensor device

In such type of transducers, the sensing element is connected directly to the thermal source. And the heat is transferred through the phenomenon of conduction. Conduction is the process by which heat is transferred from one substance to another without moving the substance.

Contactless temperature sensor

The sensor element has no direct contact with the thermal source. They use the convection phenomenon for heat transfer. Convection is the process by which the heat is transferred through the movement of the substance. The non-contact transducer is divided into the following categories.

Thermistor - The thermistor is a type of resistor, the resistance of which varies with temperature. The resistance is measured by letting the small measured direct current through, and this current causes the voltage drop across the resistor.

The resistance thermometer is divided into two types.

  • Negative Temperature Coefficient - Used to measure temperature.
  • Position Temperature Coefficient - Used to control the current.

Resistance thermometer - The resistance of metal varies with temperature. And this property of the metal is used to measure temperature. The resistance thermometer uses platinum as a measuring element and thus measures the ambient temperature.

Thermocouples - The thermocouple converts the temperature into electrical energy at the contact point. It is based on the principle that the metals have different temperature coefficients and when these two metals are put together it induces the voltage, and that voltage is directly proportional to the temperature.

Integrated circuit temperature sensor - The IC temperature sensor uses the combination of temperature sensor and electronic circuit to measure temperature. The integrated temperature sensor has a linear characteristic. The working range of the converter is very small. It is between 0 ° C and 200 ° C, which is one of the main disadvantages of the transducer.