Electrical equipment at a modern seamless tube mill

A description is given of major electrical equipment installed at a seamless-tube mill and some of the considerations that influenced its selection and design. The initial design work to rationalize different mill builders´ requirements and thus reduce the spares inventory is described. The equipment includes main DC motors and drives totaling some 20 MW for the piercer, mandrel, and stretch reducing mills. Of particular interest is a 1.6 MW low-inertia six-armature DC drive for the mandrel rack. Other equipment includes auxiliary DC drives, variable-frequency drives for roller tables, 15 Hz generating sets, and dry-type cast coil transformers. Control and automation uses eleven programmable controllers for logic sequences and mill automation and eleven microprocessors for operator interface and complex control functions.<>