Effects of the distance and test angle on the precision of infrared temperature measurement

Abstract The target distance and test angle are the main factors that affect the accuracy of infrared temperature measurement. To study the infrared temperature measurement precision of different heat source intensities at different distances and test angles, a temperature measurement test with built-in heat source within the rod of the insulator was designed. By setting four different heat source temperatures on the heating film, the temperature data were collected by infrared camera at the distances of 3, 6, 9, 12 m and 15 m and three test angles of 0 °, 90° and 180°, respectively, and the variation law of the measurement results was analysed. The main conclusions are as follows. As the distance increases, the measured values basically show a downward trend. When the distance reaches 12 m, the temperature fluctuates significantly. When the angle between the observation direction and the heat source is 0 °, the measurement value is the highest, followed by the 90° direction, and the lowest is the 180° direction, which indicates that the test angle has an obvious influence on the measurement results. With the increase of heat source temperature, the infrared temperature measurement value increases gradually and tends to be saturated. When an infrared device is adopted to measure the temperature of the insulators in service, it is necessary to pay attention to the influence of the distance and angle on the value in engineering practice.