No-load consumption is mainly due to core losses: hysteresis and eddy currents in the magnetic core material. Even with no secondary load, the primary must draw magnetizing current to maintain flux, and this causes continuous heating. Hysteresis losses result from domain realignment each cycle, while eddy current losses occur as induced currents circulate in laminations. No-load losses are nearly constant with voltage and independent of load, which is why utilities carefully specify low core-loss designs for high-efficiency operation.