Working Principle of Transformer

 

When an alternating voltage V1 is applied to the primary, an alternating flux phi is setup in the core. The alternating flux links both the windings and induces EMF’s E1 and E2 in them according to faraday’s laws of electromagnetic induction. The EMF E1 is termed as primary emf and EMF as E2 is termed as secondary emf.   

Mathematically,

                    

E1=-N1 (dphi/dt)                         and                  E2=-N2 (dphi/dt)

i.e. E2/E1 = N2/N1

hence,

E2/E1 = N2/n1 = V2/V1 = I2/I1

NOTE:-

1.   1.  The transformer action is based on the faraday’ laws of electromagnetic induction.

2. 2. There is no electrical connection between the primary and secondary. The ac power           transformer from primary to secondary through magnetic flux.

    3.There is no change in frequency i.e. output power has the same frequency as the               input power.