Q1Electrical Machines and Drives

During electromechanical energy conversion (in any rotating machine - DC or AC), the input electrical or mechanical power is not converted with 100% efficiency; several distinct loss components appear as heat, reducing the useful output. Copper losses (I^2R losses) occur in the armature, field, and any rotor windings due to winding resistance carrying current. Iron (core) losses consist of hysteresis loss (energy dissipated repeatedly magnetizing and demagnetizing the core material each cycle) and eddy current loss (circulating currents induced in the laminated core by the changing flux). Mechanical losses include friction (bearing friction) and windage (air resistance to the rotating parts). Stray load losses, a smaller miscellaneous category, arise from leakage flux pulsations and additional eddy currents induced in structural metal parts under load.