Phasing of a transformer

Phasing of a transformer: 

Two dimensional vector is known as phasor.As the vector diagram of a transformer is drawn in phasor form and this is called the phasing of transformer.

When load is applied to the secondary terminal the current that flows through the secondary terminal opposite to the primary current from lenz’s law.So flux is reduced,causes the induced emf in the primary winding is also reduced and therefore more current flows in the primary winding.This increased primary current will cause the flux to increase its original value.When more load current flow through secondary,the process is repeated.

Phasor diagram with load:

When load is connected the load current I₂ is

 lagging E₂.I₁̕  is the current that flows in the

primary winding to balance the demagnetizing

effect of I₂.Since the flux remains constant I_o

 must be the same current that energizes the

transformer at no load I₁ the actual current that

 flows in the primary Equal to the phasor sum of I₁̕ and I_O.