Rotating Magnetic Fields

[@jjggbbjunk]

The first time I saw the equations at 8:30 I thought it was magic. I had spent four years doing motor and generator repair at GE, and went back to grad school because it was not a great job. I was looking for that equation, so thank you.

[@eng.mohamedsaad9541]

Very very nice and simple discription , i hope that you have a series of videos in magnitisation principles , thanks for you . egyptian in france.

[@valovnimendez2584]

At 8:37 you explain that the three magnetic vectors Fa, Fb, and Fc are displaced in space by 120 degrees. Why isn't the 120 degree separation displayed in the vectors drawn throughout the video? It appears that the three vectors are 60 degrees apart.

[@ProfessorEssamHamdi1961]

The winding axes are displaced by 120 electrical degrees with respect to each other and, if the excitation current in all windings is the same, the mmfs will be equal in magnitude and displaced by 120 degrees (but the resultant mmf will be zero). You can check this by arranging the red phase along the Y-axis with current entering the bottom coil-side, blue and yellow phases as indicated in presentation with current entering the upper coil-sides. If the three currents are equal, then you get the 120 degree displacement (and no resultant mmf). In AC machines, however, the winding is fed from a three-phase balanced power source and, at all times ia+ib+ic=. The presentation considers specific instants of time and determines the individual mmfs and the Resultant air-gap mmf. When an individual current is zero (as it happens every half-cycle), the corresponding mmf vanishes but, at all times, the resultant mmf is equal to 1.5 the maximum phase mmf.

[@spdas5942]

Nice description !

[@imajeyelectrical581]

video is really useful but i have question that what will be effect of harmonics on the shape of rotating magnetic field ?please ans this question

[@ProfessorEssamHamdi1961]

Replied via email.

[@mouadhighwinds]

@@ProfessorEssamHamdi1961 Dear Professor, Can you please forward me the answer as I'm also interested in knowing the impact. Many thanks in advance,

[@ProfessorEssamHamdi1961]

Hi Each harmonic produce a field that is rotating its corresponding synchronous speedEach harmonic produce a field that is rotating its corresponding synchronous speedEach harmonic produce a field that is rotating its corresponding synchronous spEach harmonic produce a field that is rotating at its corresponding synchronous speed (e.g. the third harmonic produce a field rotating at three times the fundamental synchronous speed). In order to ensure smooth rotation (especially at slower speeds), design measure are taken to reduce the magnitude (and the torque produced) by the harmonics.

[@devendrapatel491]

thanks sir

[@danielchen9841]

greate vid

[@strongerpoint2538]

It is an induction motor?

[@olenaahakishyieva6326]

It depends on rotor, and only stator is depicted.

[@gensyed]

What coil? What winding? Sorry, Very difficult to follow..

[@eng.mohamedsaad9541]

This is the peinciple of aaaaaaaall machines , all motors not for certain motor .....thats mean for all kinds of coil winding ....