Transformer is a static device by which alternating electric power is transformed from one circuit to another circuit linked by a common magnetic flux without any change of frequency. It can raise or lower the voltage simply. Transformer consists two or more inductive coils which have high mutual inductance. It has two parts i.e one is i) core and second is ii) coils. If one coil of transformer is connected to a source of alternating voltage, an alternating flux is set up in the laminated core , most of the flux is linked with the other coil, according to Faraday’s Laws of electromagnetic induction (e=MdI/dt) it produces mutually-induced e.m.f. The first coil in which the a.c supply is applied, is called primary winding and others coil in which e.m.f produce, is called secondary winding which is shown in the picture.