QT9 is widely used in metallurgy, mining, petrochemical, and port terminals, shipbuilding industry and ... of electromagnetic induction, using a combination of integrated circuits approach switch, in line with the German VDE0660, IEC947-5-1 (1990), GB14048 ... the use of lightweight, easy maintenance, etc., are widely used in metallurgy, mining, petrochemical, and port terminals, shipbuilding industry and ...