Hazard rate estimation for high-voltage contacts using infrared thermography

Infrared thermography is the most common way to assess the condition of high-voltage electrical contacts in electric distribution and transmission systems. However, thermography has one major drawback as contacts carrying low or no load may not be assessed. This paper proposes a method to save and make use of thermography measurements to estimate statistical distribution parameters for the time to failure for a population of electrical contacts. The statistical distributions may then be used to support maintenance decisions for the sometimes large proportion of contacts that may not be assessed directly due to low load. As the measurement results accumulate over the years more accurate predictions can be made. The proposed method is illustrated using three test cases applied to a population of high-voltage disconnectors with randomly generated thermography measurements. The main conclusion of the paper is that using the proposed method will provide maintenance decision support for high-voltage apparatus that may not be assessed directly by thermography.