Maximum Flux in transformer core

Discussion in 'Homework Help' started by Zaraphrax, Oct 8, 2009.

  1. Zaraphrax

    Thread Starter Active Member

    Mar 21, 2009
    47
    3
    Say I have a transformer of:

    Vp = 230V - Primary Voltage
    Vs = 110V - Secondary Voltage

    N1 = 400 - Primary Turns
    N2 = 191 - Secondary Turns

    Ac = 4000 mm^2 = Core cross-sectional area

    And I wanted to calculate the maximum flux (in Tesla) when the supply voltage is at 50 Hz and neglecting all losses, would this formula be the one I am after?

    (Vp * 10^8)/(4.44FAcBmax) = N

    Thanks.
     
  2. Zaraphrax

    Thread Starter Active Member

    Mar 21, 2009
    47
    3
    Sorry, I meant Webers not Teslas.
     
  3. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    If you only require the maximum flux (rather than flux density) you don't need to know the core CSA.

    In any case I go back to basics

    Vrms = 4.44*f*N*A*Bmax = 4.44*f*N*\Phimax

    where f is in Hz, A is in m^2 and Bmax is in Tesla

    If A is in mm^2 then

    Vrms = 4.44x10-6*f*N*A*Bmax = 4.44x10^-6*f*N*\Phimax

    So whichever you need, re-arrange to give either Bmax or \Phimax

    I'm not sure where the 10^8 factor comes from in your equation - perhaps it applies to different units.
     
  4. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    Sorry, the second equation with area A in mm^2 should just be ....

    Vrms = 4.44x10-6*f*N*A*Bmax = 4.44*f*N*\Phimax

    since area is of no relevance in the case of flux \Phi
     
  5. bensm0

    New Member

    Nov 10, 2011
    1
    0
    Where has the 4.44 figure come from?
     
  6. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    It's an approximation for

    \frac{2*\pi}{\sqrt{2}}
     
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