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

2. 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. 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)

4. 3-phase Motor Stator (3 Windings, 120o apart)
The STATOR core is a stack of thin silicon steel LAMINATIONS

5. 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

6. 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

7. Production of Torque

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