Rotating Magnetic Field 3-phase Motors - 1 Rotating Magnetic Field

3-phase Motor Stator (3 Windings, 120o apart) Phase A (Red) Arrows show Magnetic Flux when phase voltage is POSITIVE Phase C (Blue) Phase B (Black) A B C 3-phase Supply (3 voltages, 120o apart)

3-phase Motor Stator (3 Windings, 120o apart) Green arrow shows flux direction Green dotted lines show resulting magnet flux Three-phase sequence produces resulting ROTATING MAGNETIC FLUX Each step is shown here at 0.5 seconds (6 seconds per cycle)

3-phase Motor Stator (3 Windings, 120o apart) The STATOR core is a stack of thin silicon steel LAMINATIONS

3-phase Motor Stator (3 Windings, 120o apart) Windings are coils placed in SLOTS around the STATOR The coils are connected in groups for each of the THREE PHASES

Speed – Frequency - Poles The SPEED of the rotating magnetic field is determined by: Frequency (Hz) x2 Poles to PAIRS x60 rps to rpm Synchronous Speed (rpm) Number of Poles per phase

Production of Torque

Production of Torque Note that the ROTOR LAGS behind the rotating magnetic field (Watch the pink dot)