Contact spot temperature and the temperature of external surfaces in an electrical connection

Infrared thermography is widely used to monitor the health of electrical power connections in live electrical lines. Although thermal imaging is helpful in locating faulty connections, surface temperature measurement alone is a poor indicator for fault severity assessment. Furthermore, under low load or other adverse environmental situations, the technique may not provide sufficient information to identify electrical connections in the initial or even advanced phases of electrical failure. This limitation stems from the large difference between the temperature of overheated electrical contact spots in a failing electrical interface and the temperature of the external surfaces of the electrical joint. This paper reports the results of calculations, based on a simple computer model, that illustrate the differences between the temperature of an electrical interface and the external surface temperature of the connection.