In electrical engineering, partial discharge (PD) is a localized dielectric breakdown (DB) (which does not completely bridge the space between the two conductors) of a small portion of a solid or fluid electrical insulation (EI) system under high voltage (HV) stress. All illustrations, descriptions and technical information included in this document are provided as indications and can cable trays are equivalent. This is often due to imperfections in the cable's construction, such as poor workmanship, water treeing, manufacturing defects, or excessive bending. If you don't know you can't work with SLD drawings. You can be a. B manufactures its cable tray in a range of materials with a variety of finishes.