Material Selection and Characterisation of Sustainable Low Voltage Busbars

Abstract

Low-voltage busbars are critical current-carrying components in switchgear systems, and growing pressure to reduce lifecycle environmental impact has motivated interest in sustainable conductor material alternatives. This thesis investigates material substitutes for the incumbent Al 6063-T6 phase rail used in the ABB CDC 40 switchgear system, aiming to maintain electrical and mechanical performance while reducing carbon footprint. An Ashby-based material selection methodology was applied, translating functional requirements into constraints, performance indices, and a multi-objective penalty function weighting material cost and cradle-to-grave carbon footprint. Five candidates were shortlisted after systematic screening: C11000 (ETP Cu), C18100 (Cu- CrZr), Al 1350-H12, Al 6101-T6, and the baseline Al 6063-T6. Finite element analysis in ANSYS Mechanical under combined thermal (IEC 61439, Temperature Rise = 70°C) and static loading established mechanical feasibility constraints, with peak support stresses of 103 MPa disqualifying Al 1350-H12. Copper alloys were eliminated on cost-weighted penalty function grounds. Al 6101-T6 emerged as the primary sustainable alternative, offering slightly higher conductivity (55% vs. 52% IACS) and a marginally lower carbon footprint than the incumbent. Characterisation of new and aged (10-year service) busbar samples via SEM and EDS revealed formation of oxides at grain boundaries around pore sites, irregular Sn plating and oxide cracking at surface, and Ni diffusion into the Sn layer in aged samples; none of which were present in new samples. Limitations such as this sample being representative of all conditions and effects of sample preparation of the morphology information were also discussed. Al-Si-Mg (6000 series) alloys are concluded to be the most viable sustainable pathway for this application