TRASFORMATORE ANULARE PER SALDATRICI DI TESTA A RESISTENZA

A transformer fot butt resistance welding of large diameter pipes has a secondary winding (4,46) which encloses a primary winding (3) and has an annular ring gap filled with electrically insulating material (10,51). At least one end portion (7,49) of the secondary winding (46) is extended out of the cavity (17) enclosing the toroidal primary winding and is positioned equidistantly realtive to the toher end portion (6,48). The gap is a min. allowable width, and the equidistant surfaces of the end portions are continuous. The ring transformer design ensures optimal secondary current conduction along the lines of force of the magnetic field generated by the ring core to involve transformer parts relatively far removed from the site of flashing during the process of preliminary flashing of the butt end being welded together.