Wire size table and fusing currents for design engineers including copper (Cu), Aluminum (Al), Iron (Fe), and Tin (Sn), wire melting amperage
and also there's a potential the weld areas were beyond the wattage/welding amperage & voltage needed fro this work? I'd have said a 300 A power supply was minimum for the work shown, and because large TIG beads were carried- I'll make the assumption at least this size power supply ...