Abstract: The transformer comprises a magnetic circuit (8) as well as, in the case of each phase, a high-voltage electric circuit (17) and a low-voltage electric circuit (18) both wound around at least one section of the magnetic circuit (8). The electric circuits (17, 18) are arranged in at least one electrically insulating annular coil form (11) which, under service conditions, is interposed between the electric circuits (17, 18) and the aforementioned section of the magnetic circuit (8). Utilization in particular is for improving the occupation of electric windows by the magnetic circuit and of magnetic windows by the electric circuit.

Abstract: Each end of an insulating tube which surrounds a transformer core projects beyond the electric circuits carried by the tube and is associated with an annular spacer member having two radially displaced bearing surfaces applied respectively against the core and the tube. An axial slit formed in the insulating tube is opened-out in order to insert a transformer core within the tube and then re-closed. A driving wheel is removably coupled to the tube in order to drive it in rotation during the winding operation.

Abstract: The transformer comprises a magnetic circuit (8) as well as, in the case of each phase, a high-voltage electric circuit (17) and a low-voltage electric circuit (18) both wound around at least one section of the magnetic circuit (8).The electric circuits (17, 18) are arranged in at least one electrically insulating annular coil form (11) which, under service conditions, is interposed between the electric circuits (17, 18) and the aforementioned section of the magnetic circuit (8).Utilization in particular for improving the occupation of electric windows by the magnetic circuit and of magnetic windows by the electric circuit.

Abstract: Each end of an insulating tube which surrounds a transformer core projects beyond the electric circuits carried by the tube and is associated with an annular spacer member having two radially displaced bearing surfaces applied respectively against the core and the tube. An axial slit formed in the insulating tube is opened-out in order to insert the transformer core within the tube and then re-closed. A driving wheel is removably coupled to the tube in order to drive it in rotation during the winding operation.