Delta Closure bus assemblies are used in the steel melting industry to close the secondary delta of a high current three phase transformer. The bus also conducts the current from the transformer through the vault wall to the power cables. As production requirements increased, the power requirements for the steel melting process increased. By the 1960s, the higher currents made it impractical to manufacture the secondary as an air cooled assembly and so the water cooled bus assembly were created. Watteredge designs and manufactures Deltas to meet your exacting requirements. As the leader in secondary bus systems, the majority of OEM furnace manufactures specify Watteredge products.