The core material and geometry determine core losses, flux distribution, and efficiency. Winding design (conductor size, layout, insulation) affects copper losses, short-circuit withstand, and leakage reactance. Insulation quality influences dielectric strength, aging rate, and reliability. Cooling ducts and oil flow paths directly impact temperature rise and load capability. Tap changers enable voltage regulation but introduce contact wear and additional losses. Structural components, shields, and leads manage mechanical forces and stray fields, influencing noise, hotspots, and long-term stability.