Question

Explain the mechanism of an electric transformer in details.

Answer 1

A transformer can be defined as a static device which helps in the transformation of electric power in one circuit to electric power of the same frequency in another circuit. The voltage can be raised or lowered in a circuit, but with a proportional increase or decrease in the current ratings. Working Principle of a Transformer:- The winding to which AC supply is connected is called primary winding and to which load is connected is called secondary winding as shown in the figure below. It works on the alternating current only because an alternating flux is required for mutual induction between the two windings. when the AC supply is given to the primary winding with a voltage of 11, an alternating

flux sets up in the core of the transformer, which links with the secondary winding and as a result of it, an emf is induced in it called Mutually Induced emf. The direction of this induced emf is opposite to the applied voltage V1, this is because of the Lenz's law, Second Coil First Coil Vi Flux Alternating Source Induced Voltage Physically, there is no electrical connection between the two windings, but they are

magnetically connected. Therefore, the electrical power is transferred from the primary circuit to the secondary circuit through mutual inductance, The induced emf in the primary and secondary windings depends upon the rate of change of flux linkage that is (N dø/dt). Dº/dt is the change of flux and is same for both the primary and secondary windings. The induced emf E1 in the primary winding is proportional to the number of turns N1 of the primary windings (E1 00 N1). Similarly induced emf in the secondary winding is proportional to the number of turns on the secondary side, (E200 N2).

Transformer Parts And construction:- The three main parts of a transformer:- 1. Primary Winding of Transformer:- which produces magnetic flux when it is connected to an electrical source, 2. Magnetic core of Transformer:- The magnetic flux produced by the primary winding, that will pass through this low reluctance path linked with secondary winding and create a closed magnetic circuit. 3. Secondary Winding of Transformer:- The flux, produced by primary winding, passes through the core, will link with the secondary winding. This winding also wounds on the same core and gives the desired output of the transformer,

As the transformer is basically a linear device, a ratio now exists between the number of turns of the primary coil divided by the number of turns of the secondary coil. This ratio, called the ratio of transformation, more commonly known as a transformers "turns ratio", (TR). This turns ratio value dictates the operation of the transformer and the corresponding voltage available on the secondary winding when a transformer is used to "increase" the voltage on its secondary winding with respect to the primary, it is called a Step-up transformer, when it is used to "decrease" the voltage on the secondary winding with respect to the primary it is called a Step- down transformer,