Why high current low voltage?
My guess is that it is an induction furnace.
It doesn't heat the metal in the furnace (oven) by the heat dissipated in the water cooled copper coil, but instead the magnetic field created by the coil creates eddy currents in the metal in the furnace that needs to be heated. These currents in the metal cause heat dissipation in the metal, so they heat the metal from within. The bigger the amplitude of the current in the coil, the bigger the amplitude of the magnetic field strength created, the bigger the current induced in the metal to be heated, the more heat getting dissipated in the metal.