Why transformer is called constant flux machine?

 Transformer work on the principle of electromagnetic induction during no-load load current(I₂) is zero because the load is not connected on secondary of the transformer
          when an alternating voltage is applied to the primary of the transformer this alternating current link with the primary winding and produce alternating flux due to this current (I₁) starts flowing through winding same alternating flux link with the secondary winding but current (I₂) will be not flowing due to open circuit in the secondary winding as seen in fig.1

Fig No.1 Phasor Diagram on No Load

    Suppose if we connect inductive load across secondary winding the load current (I₂) start flowing to make flux constant transformer induce another current component(I₁₀) in phase opposition to load current (I₂) as shown in fig.2 and hence transformer is known as constant flux machine

Fig No.2 Phasor Diagram on Inductive Load