To Measure the Temperature using RTD

Aim

To study the temperature & resistance characteristics of RTD.

Apparatus Required:

Diagram of RTD

Theory:

RTD is a resistance dependence device which has positive temperature coefficient. It is resistance type of transducer which is used for the measurement of temperature. The resistance of conductor change when temperature is changed. The main part of RTD is sensing element. The characteristics of sensing element determine the sensitivity & operating temperature range of instrument. The resistance variation with temperature is given by following relationship for most of the metals as-

R_t= R ref (1+ α ∆t)

Where,

R_t =Resistance at particular temperature

Rref =Reference temperature

α=Temperature coefficient

∆t=Temperature difference

R_t=R ref (1+ α ∆t)

R_t=R ref (1+ α ∆t)

Procedure:

1. To connect RTD sensor at the 9 pin connector.
2. Turn ON the system & see the power indicator. The red LED on the front panel will glow.
3. Give the 0° C temperatures to the RTD keeping into the ice.
4. Adjust the 0.00 °C reading on the display adjusting through zero point.
5. Keep the RTD into boiling water giving a temperature of 100° C.
6. Adjust the 100.00° C reading on display & adjusting through span pot 100 °C is calibrated
7. Keep the RTD in air in room temperature. The indicator will display room temperature.

Observation Table:

Model graphs:Resistance of the RTD increases as the temperature increases. The increase nearly follows the exponential curve-

The characteristics of various materials used for resistance thermometers are plotted-

Result: Different values of temperature are measured in various conditions.

Viva Voice:

1. On which principle it is based?
2. Which type of temperature coefficient it has?
3. Which type of sensing element is used in it?