Remaining service life diagnostic technology of phenol insulators for power distribution equipment

We have applied a remaining service life diagnostic technology to phenol insulators of power distribution equipment. Application of chemical evaluation and the Mahalanobis-Taguchi (MT) method enabled us to diagnose the insulators´ degree of deterioration with great accuracy and nondestructively on-site. Time was defined as the end of service life when electrical discharge was initiated and a remaining service life was presumed from the diagnostic results by the MT method and the year in which the master curve of service life and the threshold value intersect. Surface resistivity (threshold value) for electrical discharge initiation can be calculated from creepage distance, permittivity, frequency, etc.. It was clarified that a remaining service life for phenol insulators could be presumed by this technology because there was a good relationship between the check examination results of electric discharge initiation in the laboratory and the presumption results.