60 Acta Electrotechnica et Informatica Vol. 8, No. 1, 2008, 60–63 ISSN 1335-8243 © 2008 FEI TUKE IMPROVING RELIABILITY AND DECREASING LOSSES OF ELECTRICAL SYSTEM WITH INFRARED THERMOGRAPHY František LIZÁK * , Michal KOLCUN ** * Department of Electric Power Engineering, Faculty of Electrical Engineering and Informatics, Technical University of Košice, Masiarska 74, 042 01 Košice, tel. 055/602 3560, E-mail: frantisek.lizak@tuke.sk ** Department of Electric Power Engineering, Faculty of Electrical Engineering and Informatics, Technical University of Košice, Masiarska 74, 042 01 Košice, tel. 055/602 3550, E-mail: michal.kolcun@tuke.sk ABSTRACT Temperature and the resulting thermal behavior of electric power generation and distribution equipment and industrial electrical systems and processes are the most critical factors in the reliability of any operation or facility. Temperature is by far the most measured quantity in any industrial environment. For these reasons, monitoring the thermal operating condition of electrical and electromechanical equipment is considered to be key to increasing operational reliability and decreasing electrical losses. Keywords: infrared thermography, thermal anomaly, wavelength, condition monitoring, predictive maintenance, overheating 1. INTRODUCTION Infrared thermography (IR/T) as a condition monitoring technique is used to remotely gather thermal information for monitoring the condition of virtually all of the electrical components on an entire system and from generation to end user. Once the baseline is established, IR/T will reveal the thermal variances deviating from the norm. This localized thermal deviation can either be caused by an overheated condition or absence of heat. The information is reviewed and decisions are made for repair, or to plot the temperature change over time and repair the component at a more opportune time. The information can be stored and fully analyzed at a later date providing complete computer-aided predictive maintenance capabilities and trending. 2. HISTORY OF THERMOGRAPHY In 1800, astronomer Sir William Herschel discovered infrared, and thus began the exploration of the science of thermography. Sir William designed and created his own telescopes - becoming very familiar with lenses, mirrors and light refraction. His thermography research began with the knowledge that sunlight was made up of all the colors of the spectrum, and that it was also a source of heat, so he set out to determine which color(s) were responsible for heating objects. The first thermography experiment utilized a prism, paperboard, and thermometers with blackened bulbs where the temperatures of the different colors were measured. As sunlight passed through the prism, Sir William observed an increase in temperature as he moved the thermometer from violet to red in the rainbow created by the light. Herschel noted that the hottest temperature was actually beyond red light, and that the radiation causing this heating was invisible. He called this invisible radiation "calorific rays." Today, we refer to the light/energy as infrared, and the measuring of the heat emitted as thermography [5]. 3. SIMPLY PICTURE OF HEAT Infrared Thermography is simply a picture of heat. All the bodies emit energy from their surface as electromagnetic waves, which magnitude is directly related to their temperature. The hotter the object is, the more energy it tends to radiate. Such temperature settles the wavelength of the emitted energy; the colder the object is, the higher its wavelength will be, whereas the hotter it is, the lower its wavelength will be. This last case, is the one of the infrared energy, non visible to the human eye, but visible by means of an infrared camera [3]. The radiation measured by the infrared camera depends not only on the temperature of the object but also on its emissivity. The radiation coming from the surrounding area and reflected on the object also influences the measuring. Therefore, to measure the temperature accurately, besides the effects of different sources of radiation that interact with the object, other variables such as emissivity, distance between the camera and the object scanned, environment temperature and humidity, must also be considered. In addition, due to the characteristics of the infrared radiation, to detect any overheating by IR scans, the heat generated must be “directly” in sight of the thermographer. 4. INFRARED CONDITION MONITORING Universally, the electric industry understands that temperature is an excellent indicator to the operating condition and hence the reliability and longevity of an electrical component. Associations like IEEE, ANSI, IEC and manufacturers all publish standards and temperature ratings for electrical components. It is well understood that the life of electrical components and materials is drastically reduced as temperatures are increased. Infrared condition monitoring is the technique capable of revealing the presence of an anomaly by virtue of the thermal distribution profile which the defect produces on the surface of the component. The defect will normally