Power loss arises from core hysteresis and eddy currents, winding I²R losses, stray flux heating in structural parts, and dielectric losses. Additional contributions may come from circulating currents in parallel windings, tap changer contact resistance, and power consumed by cooling systems. Poor maintenance can increase losses through degraded oil, corroded connections, or fouled cooling surfaces. Modern designs and materials aim to minimize all these contributions while maintaining mechanical and electrical robustness.