3 phase motors 1
TRANSCRIPT
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3-phase Motors - 1
Rotating Magnetic Field
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3-phase Supply
(3 voltages, 120o apart)
3-phase Motor Stator
(3 Windings, 120o apart)Phase A (Red)
Phase B (Black)Phase C (Blue)
Arrows show Magnetic Fluxwhen phase voltage is POSITIVE
A B C
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3-phase Motor Stator
(3 Windings, 120o apart)
Each step is shownhere at 0.5 seconds(6 seconds per cycle)
Green dotted lines show resulting magnet flux
Green arrow shows flux direction
Three-phase sequence produces resulting ROTATINGMAGNETICFLUX
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3-phase Motor Stator
(3 Windings, 120o apart)
Each step is shownhere at 0.2 seconds(2.4 seconds per cycle)
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3-phase Motor Stator
(3 Windings, 120o apart)
Each step is shownhere at 0.1 seconds(1.2 seconds per cycle)
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3-phase Motor Stator
(3 Windings, 120o apart)
This shows continuous1 second per cycle
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3-phase Motor Stator
(3 Windings, 120o apart)
The STATOR core is a stack of thin silicon steel LAMINATIONS
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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
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Speed – Frequency - Poles
The SPEED of the rotating magnetic fieldis determined by:
Supply FREQUENCY in Hertz (Hz)
Number of magnetic POLESproduced by the stator windings
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Speed – Frequency - PolesThe SPEED of the rotating magnetic field is determined by:
120Synch
fN
P
SynchronousSpeed (rpm)
Frequency(Hz)
Number of Polesper phase
x2 Poles to PAIRSx60 rps to rpm
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Production of Torque
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Production of Torque
Note that the ROTOR LAGS behind the rotating magnetic field
(Watch the pink dot)