A novel method to correct temperature problems revealed by infrared thermography in electrical substations

Abstract

The need to monitor and know the state of electrical facilities and their associated equipment has become of crucial importance to ensure the continuity of electrical power supply. To this end, scientific advances result in new measuring instruments that allow diagnosing the state of electrical equipment and thus preventing failures. Infrared thermography is one of the most used methods in predictive maintenance of electrical facilities in high, medium, and low voltage. Its application in electrical substations is especially relevant due to the key role of these facilities in the power supply chain of most of customers. Its low cost, rapid implementation, and the effectiveness of the results obtained make it possible to perform thermography diagnosis several times a year if necessary. However, at the moment of taking thermography images, the electrical facility may not be subject to the maximum electrical current that can circulate through it, and, consequently, the results of the diagnosis may be erroneous since the temperature reached is not the maximum, i.e., a detected hot spot that is determined as non-problematic can become so in the nominal conditions of the facility. The need to extrapolate the results obtained according to certain current to the situation where the maximum current circulates is thus evident. In this paper, a formula is proposed to extrapolate the temperature obtained with certain current to the temperature that should be reached with higher currents, closer to the maximum values of the facility. The proposal is based on experimental data obtained from laboratory thermography tests and it was successfully used in the field.