Construction Of Welding Machine

5.2.1    WORKING PRINCIPLE OF TRANSFORMER
    The figure: shows the general arrangement of a transformer. It consists of a steel core C made of laminated sheet about 0.5mm thick insulated from each other  by thin layer of paper or vanish or by spraying the lamination with a mixture of flour chalk and water which when dried adhere to the metal. The purpose of laminating the core is to reduce the loss due to Eddy currents induced by the alternating magnetic flux.
The vertical sections of the core are referred to as the limbs while the top and bottom sections are the yokes.

The primary coil P is connected to the supply while the secondary is connected to the load. Both primary and the secondary coil are wound on the limbs.
    The physical basis of a transformer is mutual induction between two circuits linked by a common magnetic flux.
    The magnetic linked separate the primary and secondary coils electrically through a path of low  reluctance and the two coils posses high mutual inductance. An alternating voltage applied  to P circulates an alternating flux in the steel core. The main path is being represented by the dotted line D. if the whole of the flux produced by P passes  through S, the e.m.f  induced in each turn is the same for P and S (According to faraday’s law of electromagnetic induction).