Inaccuracies introduced using infrared windows and cameras

The use of infrared windows in electrical control and distribution equipment has become increasingly more prevalent over recent years. With increased focus on electrical safety and the widespread adoption by industry of NFPA-70E, infrared systems are increasingly becoming more popular. However, using infrared windows with thermal imaging cameras introduces a serious measurement accuracy problem when it comes to predictive maintenance. Current thermal imager technologies today can measure, with extreme degrees of accuracy, in the range of ± 5°C or better. However introducing any type of infrared window into a temperature measurement interjects measurement inaccuracies. This paper discusses the effects of various infrared window types on non-contact temperature measurement including the levels of inaccuracies created by alternative infrared window types, how to correct for these inaccuracies with various thermal imagers along with typical before and after accuracy results. The conclusions will provide methods for successfully using various thermal imagers along with various types of infrared window when combined within a preventive and predictive maintenance program.