Revisiting and Innovating Concepts for Shipboard Electrical Insulation Aging and Life Under Multiple Thermal and Electrical Stresses

Marine application of electrical assets can be challenging considering the upgraded targets in terms of increasing voltage, power, temperature, specific weight, dynamics, reliability and resilience. Research work has restarted, based at least on recent literature publications, on the investigation of electrothermal aging phenomenology, whose understanding would be fundamental for the design of modern and high-performance electrical and electronic asset components. There is, however, a seeming lack of remembrance on the topic, since most of these issues were already faced decades ago. This paper reconnects to past work, proposing an innovative general approach to aging rate and life modeling under combined thermoelectrical stress and showing experimental data that support the proposed models and parameters with the purpose of quantifying the extent of stress synergy. The use of aging rate additive or multiplicative models is developed, introducing a corrective coefficient whose value is an indication of the extent of synergism and of the feasibility to perform accelerated aging tests by applying electrical and thermal stress separately, rather than simultaneously. Insulating materials typically used in ship technologies, such as synthetic paper, polyamide and cross-linked polyethylene, are considered to support the proposed models. Eventually, the contribution of partial discharges to aging rate is experimentally exploited, discussed and also modeled in order to expand the electrothermal aging phenomenology to extrinsic aging (e.g., partial discharge aging).