Magnetic Circuits

Discussion in 'Homework Help' started by choboko, Jun 30, 2010.

  1. choboko

    Thread Starter New Member

    Jun 2, 2009
    An electromagnetic actuator has 2 iron poles with 5mm airgap between them. Each pole has an area of 15 cm^2. A coil of 100 turns is used to create a flux density of 1.2T in the airgap. Assume core has infinite permeability.

    Calculate the required coil current.

    So far I have the flux(phi) = B*A = 1.2 x 1.5 x 10^-3 = 1.8x10^03.
    Then from there I'm not sure where to go.
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    You don't really need to calculate the flux.

    Do you know the relationship ....

    B=\mu H

    where H is the mmf per unit length

    and hence

    B=\mu \frac{NI}{l}

    You are given B, N & l - the air gap length. All the applied mmf is taken up in the air gap. You need to decide on a value for μ. From there the only unknown is I, which is what you require.
    choboko likes this.
  3. choboko

    Thread Starter New Member

    Jun 2, 2009
    I didn't realise the airgap length was.. well length. thanks