No-load current and the relationship between the main magnetic flux phasor

In fact, the magnetic field excitation current including the establishment of the magnetization current (reactive power) im and supply loss (iron loss) is a small part of the active current iFe, im "iFe. Magnetizing current and magnetic flux changes at the same time, they are the same phase, that is, E 90 degrees ahead of or behind the terminal voltage of 90 degrees (because E ≈-u1). U1 iron phase with the flow and power consumption, advanced synthesis of exciting
  current flux angle α, called the iron loss angle. (Note map)
No-load equivalent circuit
According to the voltage balance equation derived earlier in the sinusoidal steady state are:
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Modeled the potential treatment of leakage, the introduction of excitation impedance Zm = Rm + jXm, that is, according to this equation can draw the equivalent circuit.
Parameters R1, X1σ related with the leakage magnetic circuit is constant; Rm, Xm is not constant, with the increased level of core saturation decreases. Only when the grid voltage remains near the little change in the ratings, you can change that Zm. Transformer is a large inductor.
1.3 transformer load operation
1.3.1 MMF balance equation
Transformer load operation, the secondary voltage U2 current I2 and the load impedance ZL = RL + jXL, magnetic force F2 = N2I2; one side of the current into I1, magnetic force F1 = N1I1.
Relationship still load, (ignoring the primary winding leakage impedance drop I1Z1 time), and further expressed by the scalar:, so the load of the main flux (from F1, F2 generation interaction) is approximately equal to the no-load main flux (generated by the F0). Namely:

Because the primary side leakage impedance is small, from no  load to rated load, the induced potential change is small, that the main magnetic flux is essentially the same, load that Im = I0,
   Denote the future
Order was:
One side of the current load weight, the formula that is used to offset the secondary side of the magnetic potential.
1.3.2 The voltage balance equation
Transformer equations:
           After translation of the transformer equations
1.3.3 Winding translation
Why the conversion?
Usually change much over k. The primary and secondary windings power, impedance values vary greatly, do not facilitate the calculation, low precision.
Basic equations are complex equation, solving it is very troublesome.
Transformer (same side) a circuit relations, both sides have the magnetic coupling between windings.
Therefore, in order to simplify calculations and facilitate the derivation of the equivalent circuit, winding for conversion.
The concept of translation: with a primary winding and equivalent winding turns are equal and replace the actual secondary winding.
Conversion conditions: (1) imputed magnetic potential balance between before and after the change (as long as F2 constant, the secondary impact on the primary side effect of the same)
          (2) maintain the same relationship between energy transfer (do not change the transformer to performance)
          (3) are usually converted to a secondary side (and vice versa)
Current conversion
Under the conversion condition (1) knowledge,
Conversion potential
Because the same magnetic potential balance
  between the main magnetic flux constant, E = 4.44fNφ, known potential and proportional to the number of turns, then