Error Analysis and Mitigation Strategies for Magnetic Flux Measurement in ELCID Test of Stator Core

Abstract

The electromagnetic core imperfection detector (ELCID) test is a benchmark diagnostic tool for identifying interlaminar insulation defects in generator stator cores. Given the stringent acceptance threshold of 100 mA, maintaining high measurement precision is paramount for reliable fault diagnosis. However, two critical error sources are frequently overlooked: the inherent measurement errors of integrated cables and the random measurement errors of surplus cables. Such errors may lead to erroneous diagnostic conclusions or the oversight of critical defects, potentially resulting in catastrophic generator damage. In this article, equivalent circuit models are developed to quantitatively characterize these errors and determine the governing parameters. Subsequently, three novel mitigation strategies are proposed: an independent trace winding configuration method and an excitation voltage compensation method for the inherent measurement errors, and a counter-winding cancellation technique for surplus cables for the random measurement errors. The theoretical framework and the efficacy of the proposed methods are rigorously validated through finite element analysis and experimental investigations on a prototype model. Results demonstrate that the proposed techniques effectively reduce the measurement error from nearly 10 % to less than 2 %, significantly enhancing the accuracy and reliability of ELCID testing.