What is Transformer? Definition and Principle of TransformerPublished on 24/2/2012 and last updated on 29/10/2018
Definition of Transformer
Working Principle of TransformerThe working principle of transformer is very simple. Mutual induction between two or more windings is responsible for transformation action in an electrical transformer.
Basic Theory of TransformerSay you have one winding which is supplied by an alternating electrical source. The alternating current through the winding produces a continually changing and alternating flux that surrounds the winding. If any other winding is brought nearer to the previous one, obviously some portion of this flux will link with the second. As this flux is continually changing in its amplitude and direction, there must be a changing flux linkage in the second winding or coil. According to Faraday's law of electromagnetic induction, there must be an EMF induced in the second. If the circuit of the later winding is closed, there must be a current flowing through it. This is the most basic thing on which the working principle of transformer stands. The winding which takes electrical power from the source, is known as the primary winding. Here in our above example, it is first winding. The winding which gives the desired output voltage due to mutual induction is commonly known as the secondary winding. Here in our example, it is second winding.
The form mentioned above of a transformer is theoretically possible but not practically, because in open air very tiny portion of the flux of the first winding will link with second; so the current that flows through the closed circuit of later, will be so small in amount that it will be difficult to measure.
The rate of change of flux linkage depends upon the amount of linked flux with the second winding. So, almost all flux of primary winding should link to the secondary winding. This is effectively and efficiently done by placing one low reluctance path common to both of the winding. This low reluctance path is core of transformer, through which the maximum number of flux produced by the primary is passed through and linked with the secondary winding. This is the most basic theory of transformer.