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enter image description here Here i have a picture where the waveform of magnetic fluxes of each phase is given . I know that the formula for resultant vector when magnitude of two vectors are same is 2.F.cosx/2 where F is the magnitude of equal forces(flux in this case) and x is the angle between two forces.but here i got the question:at interval 0 In the picture flux of phase 1 is 0 so we only have vector sum of 2 other phases. You can see that in the equation for resultant flux the cos of 60/2 is taken. Why is it so? Isn't it that the flux should lag by 120 ? So that we should have cos120 ?please explain this concept to me. I am good at math but i cant visualize how it actually works.

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  • \$\begingroup\$ Please use correct grammar and parse your wall of text into paragraphs, usually by context. Number your questions and put them last on individual lines. \$\endgroup\$
    – user105652
    Jan 20, 2018 at 1:31
  • \$\begingroup\$ The first thing you should do is format your question so there is paragraphs and capitalization\punctuation so people can actually read it. I'm not going to answer a question I can't read \$\endgroup\$
    – Voltage Spike
    Jan 25, 2018 at 6:46

1 Answer 1

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You need to consider the way that the three phase windings are physically positioned as well as the electrical displacements of the currents. At time zero on the diagram the flux produced by phases 2 and 3 are generally additive, but the flux produced by each is physically displaced from the phase 1 direction by 60 degrees in each direction. The amplitudes of the flux is as determined by the electrical phase displacement. It may be helpful to search for different ways that this can be diagrammed.

Edit

I think the following diagram illustrates what the author is trying to show. One space rotation of the peak of the magnetic field corresponds to one cycle of the flux waveform. At time 0, the peak of the flux waveform is halfway between the negative direction of phase 2 and the positive direction of phase 3. This the resultant is 2 X cos 30 X cos 30 X the peak flux value.

enter image description here

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  • \$\begingroup\$ Sir,It would be great if you explain this concept in bit more detail to me taking my picture in consideration.because I am new to these concepts.appereciate your help. \$\endgroup\$
    – user133933
    Jan 14, 2018 at 16:33
  • \$\begingroup\$ I will try to find a diagram that I can scan or draw a diagram. I will not be able to do that right away. \$\endgroup\$
    – user80875
    Jan 14, 2018 at 19:45
  • \$\begingroup\$ I am glad about it:) \$\endgroup\$
    – user133933
    Jan 15, 2018 at 9:10
  • \$\begingroup\$ I looked at the diagrams in your book very carefully, it seems to me that you must be correct and the book is wrong. \$\endgroup\$
    – user80875
    Jan 16, 2018 at 1:48
  • \$\begingroup\$ Upon further consideration, the result seems to be correct in the book, but there is something missing in the presentation. The problem is that we are having difficulty relating degrees in space with degrees in time. My text explains that and the analysis concludes that the resultant flux is 3/2 x maximum flux. \$\endgroup\$
    – user80875
    Jan 16, 2018 at 2:13

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