A diagram typically shows the core, primary and secondary windings, tap changer, terminals, and sometimes internal connections to bushings, CTs, and VTs. Schematic diagrams indicate winding relationships, vector groups, and phase shifts. Mechanical drawings depict dimensions, cooling equipment, and mounting points. Together, these diagrams help engineers understand electrical behavior, mechanical layout, clearances, and interfaces needed for installation, protection, and maintenance planning within the overall power system design.