Forensic Investigation of Medium Voltage Cable Failure

This case study details the forensic investigation conducted by EA Technology on a medium voltage cable failure at a large educational establishment. The investigation aimed to determine whether the failure was isolated or systemic, which is crucial for assessing the risk to other assets. The analysis revealed that the failure was due to a conductor to shield flashover, exacerbated by contaminants present in the insulation since the cable's manufacture in 1968. The findings indicated a significant systemic concern, as the high density of contaminants led to uneven electrical stress distribution and the formation of electrical trees, ultimately rendering the cable unfit for operation. The study concludes that the cable should be replaced promptly, and it recommends investigating other cables from the same manufacturer for similar issues. Furthermore, it advises asset owners to avoid certain testing methods and to be prepared for potential future failures by having replacement materials and trained personnel ready.