Estimating the Location of Acoustic Emission Sites in Solid Dielectric-Metal Composites

Abstract

Many types of power apparatus are constructed by encapsulating metals in epoxy or other dielectric materials. The desired rcsult is a complete impregnation of all air spares around the metal. \.-aids occluded in the insulation will h a v e p a r t i a l discharge which will lead to the evr.ntu:il f a i l r i r e of t h r . in~iilalion system near the void. I ’ r cwnt q u a l i t y cc)ritrol methods measure the electrical activity t l u r , t(1 p:irti:il tlischarge. If the discharge magnitude is greater t h a n a prescribed limit the apparatus is o f t r i i scrappcd I)cc:iiise of the difficulty of determining the cni isc. A technique has been developed to locate the sites of acoustic cmis~iori generated by partial discharge in such diclvct ric-metnl coinposit e structures. Insulating acoustic wavt.giiitles a r e r1iou111e.d on the surface of the apparatus a n d a r c s i i w d to rcveivcb the acouhtic emission signals prnpagating i n th(, app:iratiis. l-arious correlation implementations have h n nsed to estirnate the relative time dc1:iy between the received acoustic emissions. These time delays are then used to estimate the locations of the emission sites.