Temperature measurement using PT100

The Resistance Temperature Detector (RTD) is a temperature sensing device whose resistance changes with temperature, typically built from platinum. To measure the resistance across an RTD, apply a constant current, measure the resulting voltage, and determine the RTD resistance. The PT100 is a popular RTD with a resistance of 100Ω at 0°C. Resistance of a PT100 element is related to the temperature by the equation R(T) = R0(1 + AT + BT2), where A = 3, 9083 × 103 and B = 5, 775 × 107.

Objective

Record the temperature of a liquid by using a Pt100.

Procedure

schematics/pt100.svg

Cooling curve of water is shown in the figure below.

pics/pt100-screen.png

Discussion

The accuracy of the measurements can be increased by the following steps.

Measure the actual current from CCS and enter it in the GUI, it could be slightly different from 1.1mA. The input to A3 is amplified 11 times by connecting 1kΩ resistor from Rg to Ground. The gain and offset should be measured an entered in to the program.