DOUGHNUT-TYPE TRANSFORMER FOR RESISTANCE BUTT WELDING

DOUGHNUT-TYPE TRANSFORMER FOR RESISTANCE BUTT WELDING The transformer comprises an annular core consisting of several spirally wound cores, each tightened by rod members. The annular core is surrounded by transformer sections comprising the primary and the secondary windings. The invention resides in that the turns of both the primary and the secondary windings are shaped as sectors in the plane of the transformer cross-section. A cooled turn of the secondary winding is placed between the turns of the primary winding in each transformer section. The turns of the windings surround the annular core so that the geometric center of the annular core in the cross -sectional plane thereof and the geometric center of the annular core is farther from the transformer axis. Each turn of the secondary winding is provided with a passage for a cooling water to circulate therethrough, which water being supplied and discharged through one and the same contact ring and is first cooling one half of the whole number of the transformer sections and then the other half. The invention is useful in welding parts having a highly extended perimeter, such as large-diameter pipes for laying pipelines to convey petroleum and gas.