With the sharp increase in demand for electric power, power transformers in 400 KV ratings were produced as early as 1950. In the early 1970s unit ratings as large as 1100 MVA were produced and 800KV transformers were manufactured in the early 1980s.
A transformer is a static piece of equipment with a complicated electromagnetic circuit inside. The energy is transferred from one electrical circuit to another through the magnetic field. During this transfer of electric energy the voltage only varies and the power remains constant. The transformer works on the principle of Mutual induction. In its simplest form, a transformer consists of two conducting coils having a mutual inductance. In an ideal case it is assumed that all the flux linked with the primary winding also links the secondary winding. But, in practice it is impossible to realize this condition as magnetic flux cannot be confined. The greater portion of the flux flows in the core while a small portion called the leakage flux links one or the other winding. Depending upon the particular application and type of connection, a transformer may have additional windings apart from the two conventional windings.
There are two types of transformers available. They are
* Step-up Transformer
* Step-down Transformer
It is used to step-up the voltage to the required value. For example, from the generating station, if some 11KV is produced then it is stepped up to 230 KV using step-up transformer. It is because when 11KV is transmitted, most of the power will go as a transmission loss. So, A step-up transformer is used here.
It is used to step-down the voltage at the receiving end and making it available to the consumer.
For industries, institutions, etc., about 400 to 440V line is given. For households it is about 230V.
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