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Why the rotor will rotate in different direction

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#1 superabu


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Posted 27 October 2002 - 02:12 PM

hi, do anyone of u know that
why when we swap any two input of 3 phase induction motor, the rotor will then change rotation direction. I.E.
close-wise to anti-clock-wise, OR vice-versa.

#2 marke


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Posted 27 October 2002 - 10:51 PM

The rotor spins in the same direction as the magnetic field.
If you have a single coil only, driven by an A.C. voltage, you will in effect have two equal counter rotating magnetic fields. Adding a second coil physically displaced and driven by a phase shifted voltage, will result in reinforcement of one rotating field and give effectively a single rotating field. Likewise adding a third coil has the same result.
Reversing two phases will alter the relative pahse shift of the voltage applied to the coils and result in a counter rotating field. You could draw out the vectors at different parts of the cycle to see what the field is doing.
Best regards,

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