Winding structure for static electrical induction apparatus

A static electrical induction apparatus comprising:

• a container having an axis extending in the vertical direction;
• a pair of inner and outer insulation continuous walls disposed in said container so as to commonly include said vertical axis thereby defining a predetermined space therebetween;
• a winding assembly disposed in said space in a manner so that an inner vertical coolant passage is formed between said winding assembly and said inner insulation continuous wall, said winding assembly being composed of a plurality of coil units stacked on one another in the vertical direction with separation at predetermined intervals so as to form horizontal coolant passages between vertically adjacent ones of said coil units, each of said coil units being divided into at least two, inner and outer, coil sub-units disposed concentrically with each other in a common horizontal plane to thereby define an intermediate vertical coolant passage between the vertically stacked inner coil sub-units and the vertically stacked outer coil sub-units, said inner, outer, and intermediate vertical coolant passages communicating with each other through said horizontal coolant passages, said intermediate vertical coolant passage being generally divided into a plurality of regions by a plurality of vertical arrays of horizontal spacer members radially extending in said horizontal coolant passages for ensuring said horizontal coolant passages;
• and
• a plurality of coolant flow control members disposed in circumferentially and axially discrete relation from one another in said intermediate vertical coolant passage in a manner so that a horizontal sectional area of each of the regions of said intermediate vertical coolant passages is decreased, but not substantially completely closed, periodically at a pitch of nP along the vertical direction, where n represents an integer which is not smaller than two (2) and P represents a pitch of said coil units along the vertical direction, each of said coolant flow control members having a width in the radial direction being selected to closely correspond to a width in the radial direction of said intermediate vertical coolant passage.