Development of Simple Method for Quality Testing of PT100 Sensors Due to Temperature Coefficient of Resistance Measurement

The platinum-100 (PT100) is the one type of temperature sensor which is widely used not only in industry but also in Calibration Laboratory, especially in room condition. To assure the measurement accuracy, it is necessary to have a simple alternative method to test the quality of a PT100 resistance thermometer. This research aims to develop a measurement technique to determine the estimated temperature coefficient of resistance value from platinum resistance thermometer as finding a simple quality testing method. The microcontroller, chip of Analog to Digital Conversion (ADC) 24-bit, amplifier, and voltage divider schematic are applied to acquire serially in the real-time the raw data from the sensors of PT100 as proposed instrumentation system of applied its mathematical definition. Thermometer calibration has been performed using a standard thermometer which has been traceable to SI units through primary standards of temperature at the National Metrology Institute (NMI) of Indonesia to get the international measurement truth value recognition. Experiment results indicated that the voltage divider technique has better performance than the Wheatstone bridge method. Although the results of calibration and measurement of two examples of PT100 sensors in the measuring range of room condition (20-30) ° C achieved the 0.5 °C accuracies by 0.40 °C and 0.20 °C, respectively, the different calculated temperature coefficient of resistance values between both are around 0.0268 and 0.0092. The differences in measurement quality have possibly been caused by error and the purity of platinum for each sensor. That simple alternative method to test the quality and purity of PT100 sensor material in the market is worthy of being proposed as temperature coefficient measurement, which implemented its mathematical definition.