WINDING OF ON-LOAD TAP CHANGING TRANSFORMER

PURPOSE:To make a transformer small-sized and lightweight by providing most coarse tap windings on the upper and lower end portions of a high-voltage primary winding as coarse tap primary windings, and arranging the remaining coarse tap windings in parallel integrally with dense tap windings as coarse secondary tap windings. CONSTITUTION:The windings of a on-load tap changing transformer are formed by two winding blocks, namely, primary winding blocks in which coarse tap primary windings 8A, 8B are arranged on the upper and lower end portions of a high-voltage primary winding 3, and dense tap winding blocks 10A, 10B in which coarse tap secondary windings 9A, 9B and dense tap windings are arranged in parallel and wound. Whereupon, the usual two insulating portions become one insulating portion d between the high-voltage winding block and the blocks 10A, 10B, Therefore, the radial size of the winding becomes small, the size of the outer peryiphery of the winding becomes small, and the size of the core window is reduced. With this, the transformer is made small-sized and lightweight.