An ink set including at least three black ink compositions different in concentration, wherein the colorant of the black ink composition having the highest concentration is a pigment, the colorant of the black ink composition having the lowest concentration is a dye, and the colorant of the black ink composition for medium gradation having medium concentration between them is a pigment or dye. Data obtained by a SCADA system may be stored in a real-time status database and a historian database. The engine is controlled using feedback indicative of a welding output operating parameter.