Understanding Infrared Windows and Their Effects on Infrared Readings

The use of infrared (IR) 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, IR systems are increasingly more popular. However, using IR windows with thermal imaging cameras introduces a serious problem when it comes to predictive maintenance, i.e., measurement accuracy. This paper discusses the effects of various materials used in IR windows for noncontact temperature measurement. Varying degrees of measurement inaccuracy and methods to correct for these inaccuracies with various thermal imagers is covered. Other factors outlined will include the factors affecting IR transmission through various IR window materials used in various practical electrical inspection applications. Moreover, how these various materials affect the accuracy of the readings and ways to correct these various transmission losses will be also addressed. The conclusions provide the details for a successful preventive and predictive maintenance program when using various thermal imagers along with different types of IR windows.