The calculation of magnetomotive force (MMF) in a transformer can be performed using the relationship between primary inductance, current, and the magnetic field. Specifically, the formula (1/2) L I² = (1/2) ∫ B H dV is utilized, where L represents inductance, I is the magnetizing current, B is the magnetic flux density in Tesla, H is the magnetizing force in amp-turns per meter, and V is the volume of the magnetic material. The relative permeability (u) and the permeability of free space (u0 = 4π x 10^-7 H/m) are critical in determining the B field. This approach allows for accurate calculations of MMF when the output of the transformer is open-circuited.
PREREQUISITESElectrical engineers, transformer designers, and students studying electromagnetic theory will benefit from this discussion, particularly those focused on calculating magnetomotive force and understanding transformer behavior under open-circuit conditions.