Material Selection and Characterisation of Sustainable Low Voltage Busbars

Sammanfattning

Low-voltage busbars are critical current-carrying components in switchgearsystems, and growing pressure to reduce lifecycle environmental impact has motivatedinterest in sustainable conductor material alternatives. This thesis investigatesmaterial substitutes for the incumbent Al 6063-T6 phase rail used in the ABB CDC40 switchgear system, aiming to maintain electrical and mechanical performancewhile reducing carbon footprint.An Ashby-based material selection methodology was applied, translating functionalrequirements into constraints, performance indices, and a multi-objective penaltyfunction weighting material cost and cradle-to-grave carbon footprint. Five candidateswere shortlisted after systematic screening: C11000 (ETP Cu), C18100 (Cu-CrZr), Al 1350-H12, Al 6101-T6, and the baseline Al 6063-T6. Finite elementanalysis in ANSYS Mechanical under combined thermal (IEC 61439, TemperatureRise = 70°C) and static loading established mechanical feasibility constraints, withpeak support stresses of 103 MPa disqualifying Al 1350-H12. Copper alloys wereeliminated on cost-weighted penalty function grounds. Al 6101-T6 emerged as theprimary 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 andEDS revealed formation of oxides at grain boundaries around pore sites, irregularSn plating and oxide cracking at surface, and Ni diffusion into the Sn layer in agedsamples; none of which were present in new samples. Limitations such as thissample being representative of all conditions and effects of sample preparation ofthe morphology information were also discussed. Al-Si-Mg (6000 series) alloys areconcluded to be the most viable sustainable pathway for this application