CHAPTER 3 - TRANSFORMER

INTRODUCTION OF TRANSFORMER

A transformer is a static device used to transfer energy from one ac circuit to another. This transfer of energy may involve an increase or decrease in voltage, but the frequency will be the same on both circuit. When the transformation takes place with an increase on voltage, it called a step-up transformer, and step-down transformer for vice versa.

Without transformer the widespread distribution of electrical power would be impractical.   Transformer makes it possible to generate power at a convenient voltage for long distance transmission, and then step down for practical distribution.

Basic transformer consist of two windings/coil wound around on an iron core. The principle of transformer’s operation is based on mutual induction which occurs when the magnetic field surrounding one conductor cuts across another conductor, inducing a voltage on it. This effect may be increased by forming the conduction into coils and winding them on a common magnetic core.

When the primary coil of transformer is connected to an alternating voltage, there will be a current in primary coil called the exciting current which will set u an alternating flux that links the turns and induced voltage in both windings.

Function of transformer:

· The function of a transformer is to increase voltage prior to sending electricity over long distances through wires. They also function to decrease the voltage of electronic products to a level that is appropriate for the voltage circuits contained in the product.

· The function of a transformer is to move electricity currents between circuits within an electrical system. This is done via inductive electrical conductors.

      A transformer is a very common magnetic structure found in many everyday applications. AC circuits are very commonly connected to each other by means of transformers.
      A transformer couples two circuits magnetically rather than through any direct connection. It is used to raise or lower voltage and current between one circuit and the other, and plays a major role in almost all AC circuits.

Application Example: Transformers are a necessary part of all power supplies.

Application Example: Electric power systems

    Transformers find many applications in electric power distribution where they are employed for increasing or decreasing voltage levels.

References:

          Petruzella, Frank. 1996. Industrial Electronics. Mc-Graw Hill. Singapore

vlab.ee.nus.edu.sg.Transformer. http://vlab.ee.nus.edu.sg/~bmchen/courses/EG1108_Transformers.pdf 20 April 2014