Estimating off-line high voltage apparatus dielectric loss and DC contact resistance with on-line infrared measurements

Simple thermodynamic models can be used to estimate the watt loss of in-service high voltage apparatus. The operating watt loss of many electrical system components can then be analyzed to estimate the dielectric loss or contact resistance. The technique requires temperature data that is normally obtained with an infrared camera, basic apparatus dimensional data and system conditions at the time of the infrared scan. This paper demonstrates how practical heat transfer calculations can be used to translate online thermal test data into estimates of offline dielectric loss and contact resistance