Evaluation of the degree of deterioration of circuit-breaker insulators using chemical analysis and the Mahalanobis-Taguchi (MT) method

We have developed a novel evaluation technique of the deterioration degree of insulators for breakers using a chemical analysis and the Mahalanobis-Taguchi (MT) method. It is possible to evaluate the deterioration degree with great accuracy and nondestructively on-site by this technique without the effect of humidity and external noise such as electromagnetic waves. The mechanism of the insulator's surface resistivity reduction was clarified, and it was found that the deterioration degree of insulators could be evaluated by this technique because a linear relationship existed between the results judged by the MT method and the actual measurement results for the surface resistivity. In comparison to electrical methods, such as partial electric discharge and megohmmeters, the evaluation accuracy has been improved by three digits and the range of the deterioration degree that could be evaluated was expanded by seven digits.