<p>The magnetic device consists of a cylindrical conductor (2) forming a hollow space with terminal connections (1, 3) and an inlet (4) and outlet (5) for cooling medium. A sealing-element (11) is fixed to the cylindrical conductor (2). Wound magnetic cores (6) are of magnetic band laminated by insulating layers and with a certain space between adjacent magnetic cores (6). The outer ring-element (7, 8) between the magnetic cores (6) and the cylindrical conductor (2) has a channel through which cooling-medium flows, enabling cooling-medium to flow radially or around each wound magnetic core (6).</p>
