What is a Transformer?Mutual Induction? Necessity of Transformer?Working Principle of a Transformer

What is a Transformer?

Transformer is a static device which is used to transfer a.c electrical power from one circuit to another circuit at same frequency but at different voltage levels.

When voltage at the output side is more than the input side then it’s know as step up transformer and when the input voltage is more than the output voltage then it is known as step down voltage. Exp. if input voltage is V1 and output voltage is V2, if V1>V2 then it is Step up voltage and if V1<V2 then it’s a step down transformer.  In this case only voltage is change form one level to another level but frequency remains same.

  

                     

                                                    Transformer

                                     If V1>V2 Step Up Transformer

                                    If V1<V2 Step Down Transformer

 Necessity of Transformer

Usually in India voltage is generated at power station is at 11kV or 33kV. But these generating stations are located very far away from the load centers. So to use the electrical energy at the load centers, voltage is step up at very high voltage (400kV or 220kV) with the help of transformers and transmitted to load center with the help of transmission lines. Voltage is step up at very high level due to economical reason.

But usually we use the electrical power at very low voltage say 440V or 220V due to safety reasons. So to use electrical power at this voltage, we need to step down the voltage at our working voltage level. This is achieved with the help of step down transformer. Thus transformers plays very important role in power system.

Working Principle of a Transformer

The Basic principle of a transformer is Electromagnetic Induction.

 A simple form of transformer is shown in fig. transformer is consists of two winding name as Primary and secondary winding. These winding are placed over a laminated silicon steel core. The winding which connected to the main line or main supply is know as Primary winding and the winding which is connected to the load is known as secondary winding. 

When a. c supply V1 is connected to the primary winding, alternating current start to slow in the primary winding. When alternating current flows in the primary winding, it set up alternating magnetic flux around the winding. as this winding is place over the laminated silicon steel core, this alternating flux liked to the core. As we have already explained that secondary winding placed on this core. 

If we remember the Faraday law of electromagnetic induction , when a conductor is placed near to the changing magnetic field, voltage will be induced in the conductor. same thing is happen in the case of transformer. when changing magnetic field in the core induced by the primary  circuit, linked with secondary circuit, voltage E2 is induced in the secondary circuit, which is known as mutual induced e.m.f. But the Voltage induced in the secondary is in opposite direction then the primary according to Lenz's Law.

Primary winding also comes under in this changing magnetic filed and due to this a voltage is also induced in this primary winding, which is know as self induced e.m.f but this voltage also act in opposite direction then apply voltage V1.

As we have seen that there is know direct connection between primary ans secondary winding but electrical power is transfer from one circuit to another through mutual flux.