Hitachi, Ltd.

Teruo Fukuda

Yoshitake Kashima

Tetuo Otomo

Ryozi Nakatake

Low, middle and high voltage windings are wound on a magnetic core in this order, the high voltage winding having a high voltage line terminal at its center and neutral terminals at both ends. Two middle voltage partial windings are coaxially wound on the outside of the high voltage winding at upper and lower positions separated by a necessary distance for insulation. One end of each of the middle voltage partial windings are connected to the neutral point of the middle voltage winding, and the other ends thereof are each connected to the respective tap windings of two tap changers. Thus, the middle voltage partial windings and the tap changers constitute a parallel circuit in which a circulating current flows thereby to induce magnetic flux in each of the middle voltage partial windings and tap windings. The middle voltage partial windings and tap windings are so wound that the magnetic coupling therebetween through the induced magnetic flux can be reduced.

Three winding transformer

Disclosed is a transformer of a large capacity for an ultra-high voltage which comprises a core leg coaxially wound sequentially with at least a low voltage winding, a high voltage winding composed of an upper and a lower winding section operated in a parallel connection and having a lead conductor led out from a center portion of the high voltage winding and extending to a terminal to be connected to a high voltage transmission line as well as connection leading-out wires taken out from the top and bottom end portions of the high voltage winding, and an upper and a lower tap winding disposed vertically spaced from each other with a predetermined distance and respectively connected to the upper and lower winding sections of the high voltage winding so as to be operated in a paralled connection therewith. Each of the upper and lower tap windings are disposed such that the magnetic center of each of the tap windings may be located at a height which corresponds to a value in the range of 55 to 65% of the height between the center portion of the high voltage winding at which the lead wire is led out and either ends thereof, whereby axial mechanical forces produced electro-magnetically in the tap windings are significantly reduced and the manufacture of the transformer is facilitated with an improved reliability thereof.

Growing community of inventors

Hitachi, Japan

Teruo Fukuda