CABLEGNOSIS Project: Ageing Studies on Insulating Materials and Superconducting Wires for Cable Applications

To ensure power cables' lifetime and to prove their reliability, standardized type and PQ tests are carried out, e.g., withstand voltage test. Usually, polymeric materials (typically polyethylene) are used as dielectric materials. Standard testing procedures integrate extrapolations using the analytical ageing laws mostly related to thermal and voltage ageing to investigate the impact of thermal stress and excessive temperature on lifetime of the cable insulation. Superconducting (SC) cables are cooled and maintained at a cryogenic temperature, below 77 K. In such conditions, one can expect different ageing mechanisms to be dominant rather than thermal ageing, and consequently ageing laws might be different that will impact standard type tests. To perceive the ageing law and guide the future process of manufacturing, and developing techniques for prognostic health management of SC cables as well as to predict when maintenance might be needed, ASG superconductors, University of Glasgow (UofG) and École supérieure de physique et de chimie industrielles de la ville de Paris (ESPCI) are involved in work packages related to the ageing mechanisms affecting both insulation materials and SC wires within the framework of CABLEGNOSIS project. This article presents insights on the ageing mechanisms at cryogenic temperature, an innovative prediction methodology based artificial intelligence and strategies to accelerate the ageing and acquire accurate physical information up to breakdown.