Aging in Commercial Thick- and Thin-Film Resistors: Survey and Uncertainty Analysis

Accurate measurements are essential to the modern power system. Power system instruments and measuring systems must remain within accuracy specifications for upward of 25 years without intermediate calibration. Since resistors are integral to measurement methods, the safety, reliability, and economy of the power grid are crucially dependent on the long-term performance of resistors. However, few peer-reviewed sources exist to guide uncertainty analyses, which must account for a long-term resistor drift. This article contributes to a much-needed literature survey and codifies commonly accepted results. Based on the results, an estimation method is developed, which assumes that activation energy and time-dependence parameters are independent, Gaussian, random variables. The distribution of an end-of-life resistor drift is derived, and a maximum drift factor is calculated. This drift factor can guide the development and evaluation of industrial power system instruments and measuring systems. Default values for activation energy, time dependence, and their standard deviations are proposed based on the observations in the literature. Finally, the estimation method is applied to commercially available precision thin-film resistors. The resulting data set is analyzed and generalized across manufacturers.