Embodiments concern a plant for melting and/or heating metal material and a corresponding method to supply electrical energy. The plant comprises at least one induction furnace (11) and means (12) for supplying electrical energy to the induction furnace 11), wherein the electric power supply means (12) comprise at least one transformer (13) connected to an alternating current mains power network (14), at least one rectifier (15) located downstream of the transformer (13), at least one converter (16) located downstream of the rectifier device (15), and at least one coil (17) for melting and/or heating metal material.

The present disclosure discloses a magnetic device for induction heating thereof that relates to the field of induction heating technologies. The magnetic device includes at least four coils that are even numbers, wherein the at least four coils are equally divided into two groups, and the two groups of coils are symmetrically arranged around an axis thereof; and a driving unit arranged on a symmetrical central axis of the coil and configured to drive a metal material to be heated to rotate. The present disclosure provides the even number of coils combined to form an annular coil device, so that a larger and more uniform magnetic field is generated in a center of the annular coil device, which can be more favorable for improving an eddy current heating effect thereof.