Insulation structures for electrical inductive apparatus

A power transformer comprising:

• a tank;
• a dielectric fluid disposed in said tank to cool and insulate said transformer;
• a magnetic core having a plurality of horizontally-spaced, vertically-extending leg portions of rectangular cross-section connecting first and second yoke portions disposed in said tank;
• a plurality of electrical winding assemblies disposed in inductive relation with said leg portions of said magnetic core and having a substantially rectangular cross-sectional configuration;
• a support structure disposed in registry with said magnetic core and said electrical winding assemblies to provide a solid structure that resists movement of said electrical winding assemblies;
• solid insulation means disposed between at least the adjacent portions of said electrical winding assemblies and between adjacent portions of said electrical winding assemblies and said support structure to provide insulation therebetween;
• each of said electrical winding assemblies including concentric first and second electrical windings, each formed of a plurality of layers of conductor turns, said first and second electrical windings being subject to radial movement under forces incident to a short circuit;
• and
• each of said electrical winding assemblies including first and second insulation structures, said first insulation structure being disposed between said first and second electrical windings and said second insulation structure being disposed between said second electrical winding and adjacent portions of said solid insulation means;
• said first and second insulation structures being disposed in movable relation with respect to said first and second electrical winding and said solid insulating means, respectively, to permit relative movement between said first and second insulation structures and said first and second windings and said solid insulating means under forces exerted on said windings during a short circuit;
• each of said first and second insulation structures including a plurality of spaced, vertically extending spacer members arranged in a first layer and forming a plurality of passages for the flow of said dielectric fluid therethrough, at least one layer of electrical insulating material being disposed on each opposing side of said spacer members with each of said layers of electrical insulating material being unbonded to adjacent portions of said windings and said solid insulating means so as to permit relative movement therebetween;
• said spacers being securely held in a vertical orientation to said layers of electrical insulating material by a B-staged adhesive coating on the surface of said spacers and a plurality of turns of a B-staged adhesive impregnated, electrical insulating strip material disposed around said spacers, which adhesive, when cured, cohesively bonds said spacers to said adjacent layers of said electrical insulating material.