Imaging of voids in dielectric materials by x-ray induced partial discharge

A nondestructive testing technique for imaging of voids and inclusions in dielectric materials for high-voltage application is described. Void partial discharge occurrence is induced by a narrow pulsed x-ray beam scanning the bulk of epoxy sample. Phase resolved partial discharge analysis is recorded as a function of the beam position. The data matrix is used to construct digital gray scale images, which gives information about location, dimensions, and partial discharge activity in each defect in dielectric materials. This nondestructive technique can be an important tool to evaluate the degradation state of the material.