Multi-Channel Virtual Instrument for Measuring Temperature—A Case Study

Abstract

The article presents the hardware and software configuration of the developed multi-channel temperature measurement system as well as calibration procedures and measurement results verifying the properties of measurement channels. The system has been developed and dedicated primarily for measuring the temperature distribution in a laboratory model simulating underground power lines. With the adopted configuration of the analog part of each measurement channel, the main functions in the system developed as a virtual instrument are performed in its software. The instrument input circuits contain NTC (negative temperature coefficient) thermistors used as temperature sensors. The resistance of each of the thermistors connected in the voltage divider circuits is converted into a voltage. The obtained voltages in the measurement channels, after analog-to-digital conversion (ADC), are processed in subsequent operations in the instrument’s software. In addition to the basic function of the device, which is the multi-channel temperature measurement, the operations of identifying the characteristics of the thermistors used and calibrating each of the individual measurement channels are performed. The article contains sample results of the calibration of measurement channels and temperature verification measurements used to evaluate the properties of the developed system. The obtained inaccuracy of the temperature measurement in each of the channels is less than 0.4 °C.