Enhanced and Precise Estimation of Dielectric Loss in Damped AC Voltage Tests

This paper presents an extended approach based on a recently developed method, designed to enhance the accuracy of dielectric loss factor (loss tangent) estimation in damped alternating current voltage (DACV) tests. The estimation process leverages a precise equivalent circuit of the DACV testing system, along with an accurately determined attenuation factor and angular frequency of the measured test voltage, to improve the reliability of loss tangent calculations. The extended approach introduces a new expression for loss tangent, derived from peak-to-peak testing voltages, and incorporates a moving average filter to mitigate the effects of DC offset, amplitude and time quantization errors, and noise. A comparative analysis of simulation and experimental results demonstrates that the conventional method lacks precision in estimating the loss tangent, especially when measuring values as low as 0.1%—a typical range for both new and aged underground power cables. However, the proposed extended method provides reliable loss tangent estimation within this range, ensuring acceptable accuracy and improved measurement consistency.